A74 CLINICAL CHEMISTRY, Vol. 56, No. 6, Supplement, 2010

Tuesday, July 27, 2:00 pm – 4:30 pm Electrolytes/Blood Gas/Metabolites

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Prevalence of Falls and Fractures in Hyponatremic Patients Presenting to an Emergency DepartmentS. D. Thomas, G. H. White, P. S. Coates. SA Pathology, Adelaide, Australia,

Background: Hyponatraemia is the most common electrolyte disturbance and is caused by either salt and water loss or water retention. The condition has been associated with gait disturbances and falls. Identification of hyponatremia early in the elderly may be important in reducing morbidity and mortality. We undertook a clinical audit of emergency presentations by patients with hyponatremia.Methods: All consecutive emergency presentations to a tertiary level hospital who had an initial plasma electrolyte evaluation with a Na≤129 mmol/L were selected (reference interval for plasma Na 135 - 145 mmol/L). Plasma osmolality, K, Cl, emergency and discharge diagnosis for each patient were collated.Results: During Jan-Aug 2009, 375 specimens (from 300 patients) with Na≤129 mmol/L were received from the emergency department (ED). Only 59 specimens had an osmolality requested (16%). Forty one of 300 patients presented to ED with a history of recurrent falls (13.7%) of whom 18 (43.9%) sustained a fracture as a result of the fall. The mean plasma Na in the fracture patients was 126 (120-129 mmol/L) similar to the mean for all patients with falls (125.7, range 119-129 mmol/L; mean age 81, range 55-96y) but significantly less than age matched controls (P<0.001) admitted with conditions other than falls or trauma. Conclusion: The incidence of hyponatremia in patients with fractures has been reported to be higher than other patients presenting to ED. However only a small proportion of these patients have their hyponatremia investigated further. Falls and fractures are more likely to occur in patients with mild to moderate hyponatremia, suggesting the need for careful follow up and correction of Na levels in the elderly in the community.

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Abbott ARCHITECT ICT (ISE) Module Use-Life Response Characteristics J. L. Seago, Q. Li, D. Pistone. Abbott Laboratories, Irving, TX,

Objective: Characterize the use-life performance of the Integrated Chip Technology (ICT), a solid-state ISE module before and after testing over 15,000 samples over 2 months.Relevance: Electrolytes, especially Potassium, are critical STAT tests requiring quick, accurate results. Sodium, Potassium and Chloride results are available within 3 minutes from 15 μL of Serum, Plasma or Urine on the Abbott ARCHITECT Clinical Chemistry Systems. The ICT module is calibrated once per day and warranted for 15,000 samples (45,000 tests) or two months use.Methodology: 24 hour Calibration Stability, Linearity and Precision were evaluated on modules that processed 12,000, 17,000 and 22,000 samples. NIST SRM 909b, Linearity Standards, Controls, revised ICT Calibrator and new concentrated ICT Sample Diluent (55 and 90 mL cartridges) automatically diluted by the instrument, were used to characterize the ICT Module for Linearity, Precision and Accuracy.Validation: Improvements were evaluated for Precision (EP5-A2), Linearity (EP6-A) and Accuracy (Six Sigma metric). The 24-hour calibration interval imprecision data represents typical response from an ICT module after processing the indicated number of samples. Sigma values are from a module that tested 22,000 samples over two months with 3 reps of NIST SRM 909b.Sigma metric: (Sigma=[(TEa(%)-Bias(%))/CV(%)] as per westgard.com using RiliBäk TEa targets.Results:

* S=Serum, U=UrineConclusion: The claimed ICT Module performance was confirmed after testing >15,000 samples over 2 months. Recent ICT improvements resulted in better accuracy and precision especially for Potassium with a 24-hour calibration interval. Sigma metrics demonstrate improved quality confirming the Abbott ICT Module is well suited for use in the Clinical Chemistry Laboratory over its intended use life. The new concentrated ICT Sample Diluent (700/1200 samples/cartridge) eliminates the need for multiple cartridges on-board the system, freeing up more reagent positions for laboratories to run additional assays in-house.

Tuesday PM, July 27

Poster Session: 2:00 pm – 4:30 pmElectrolytes/Blood Gas/Metabolites

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Comparison of Glucose and Electrolyte Concentrations among Plasma Samples Obtained from Various Types of the Combination between Lithium Heparin and Antiglycolytic Agents W. Boonlert1, R. Wiriyaprasit2, N. Nuanmuang1, S. Oo-puthinan3, A. Chittamma4. 1Department of Medical Technology, Faculty of Allied Health Sciences, Naresuan University, Phitsanulok, Thailand, 2Regional Science Institute, Phitsanulok, Thailand, 3Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand, 4Clinical Chemistry Division, Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand,

Background: Lithium heparin (LH) plasma samples have been used recently in urgent cases for simultaneously measuring glucose and routine biochemical testing. Previous studies introduced several antiglycolytic agents and combined those with LH for using in clinical chemistry testing. There were many arguments that had been discussed on the efficiency of these agents. The objectives of this study were to compare glucose and electrolyte concentrations among the combinations between LH and various antiglycolytic agents.Methods: Twenty millilitres of fasting blood samples were collected from venipuncture from 20 healthy volunteers and 20 diabetic patients. Each sample was aliquot into pain, sodium fluoride (NaF), LH, and Plasma glucose, sodium (Na+), potassium (K+), and chloride (Cl-), concentrations were measured in serum, NaF, LH, LH plus various antiglycolytic agents, 10.0 mmol/L glyceraldehydes (GA), 9.8 mmol/L of tris-bromoacetate (BA), or 16.7 mmol/L of D-mannose plasma samples at 0th, 2nd, 4th, 6th, and 8th hours after blood drawing. Pair t-test was used for data analysis.Results: Blood samples treated with LH plus D-mannose and LH plus tris-bromoacetate could preserve glucose levels effectively for up to 8 hours and did not significantly differ from using plasma NaF (p>0.05). Most plasma samples obtained from LH plus antigycolytic agents could be used for electrolyte analysis, except for the LH plus BA plasma that showed slightly hemolysis at 4 hours.Conclusions: Plasma LH plus 16.7 mmol/L of D-mannose was the most efficiency for glucose and electrolyte determinations. The effect of this combination on other biochemistry should be further investigations.

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Urinary pH Levels between Healthy and Metabolic Syndrome VolunteersW. Boonlert, S. Rapiya, A. Karaged, O. Narksing. Department of Medical Technology, Faculty of Allied Health Sciences, Naresuan University, Phitsanulok, Thailand,

Metabolic syndrome (MetS) is characterized by a group of metabolic risk factors that present in an individual. MetS has been linked to the abnormal biochemical processes involved in the body. Thus the body must have homeostasis processes to filtrate by kidney and show this processes with pH in urine. The objective of this study is to compare urinary pH levels obtained from healthy and MetS volunteers. The MetS was classified by using the NCEP-ATP III guideline and defined as having at least three criteria in an individual. Twenty milliliters of first morning urine samples were collected from 100 volunteers (50 healthy and 50 MetS volunteers) and urinary pH levels were measured using a pH paper and a pH meter. The median of pH determined by a pH paper was not significant different from those measured by a pH meter (p>0.05). The median of pH in healthy and MetS volunteers were 6.5 and 6.00 respectively. The median of urinary pH obtained in healthy was statistically significant higher than those obtained from MetS volunteers (p<0.001). Sensitivity and specificity of urinary pH levels were 82% and 90% respectively when used a cut off point ≤ 6.00 measuring by pH papers and MetS risk increased 8.2 times when compared to lower pH levels. In conclusions, urinary pH was different between MetS and healthy volunteers. Urinary pH ≤ 6.00 measured by pH paper could be used to distingue MetS from healthy.

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Tuesday, July 27, 2:00 pm – 4:30 pmElectrolytes/Blood Gas/Metabolites

0.05% ammonium acetate. Spiked bronchial washings were also subjected to the enzyme-based spectrophotometric assay.Results: There was adequate baseline separation of all four species (RT: TCA 1.71min, CA 2.72 min, DCA 4.23min, CDCA 4.49min). Estimates of ionization suppression ranged from 13% (DCA/CDCA) to 50% (CA/TCA). Recoveries for each individual bile acid ranged from 65% for high concentrations of CA (50uM) to 95% for mid-range concentrations of TCA (5uM). The LC-MS method is linear from 0.05 to 100uM for all compounds (0.2-400uM TBA), exceeding the linear limits of the spectrophotometric method in bronchial washings (3.25-100uM TBA). The overall inter-injection and inter-assay precision for each bile acid species at high (50uM), medium (5uM) and low (0.5uM) concentrations were <3% and <10%, respectively. Inter-assay precision for TBA by LC-MS and trinity methods were comparable (50uM: 18% by LC-MS, 16% by Trinity; 5uM: 27% by LC-MS and 26% by Trinity). Correlation between the two methods on spiked samples was excellent (R2=0.96).Conclusions: We have developed an LC-MS method for the quantification of 4 individual bile acid species in bronchial washings. Our method performs similarly to a commercially-available assay in the measurement of TBA in bronchial washings. It will be useful for future studies examining the role of specific bile acid species in the pathogenesis of BOS.(1)D’Ovidio et al. J Thorac Cardiovasc Surg. 2005 May;129(5):1144-52

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Standardized Enzymatic Creatinine on the Dimension VistaC. Feldkamp, M. Cosman, J. Zajechowski, J. Carey, V. I. Luzzi. Henry Ford Hospital, Detroit, MI,

Background: Serum creatinine concentration is used to estimate glomerular filtration rate (eGFR). In 2006, new recommendations by the laboratory working group of the National Kidney Disease Education Program (NKDEP) established that creatinine methods use to calculate eGFR should be standardized. Although the Jaffe method is commonly used in clinical laboratories to measure creatinine, it may overestimate this metabolite due to non-creatinine interferences. The enzymatic method also shows some interferences but it does not have the bias shown by the Jaffe method. Objective: To evaluate the standardized enzymatic Dimension Vista creatinine assay (eCREA) and use it to calculate eGFR as recommended by the NKDEP. Method: De-identified serum specimens or commercially available material were used to investigate the accuracy by comparing the current creatinine assay (modified kinetic Jaffe) with the eCREA. Precision and linearity were also measured. Comparison of the eGFR using the Modification of Diet in Renal Disease (MDRD) or the modified MDRD was performed for eGFR below 60 mL/min/1.73m2. EP evaluator or Microsoft Excel was used to analyze the data. Results: The current creatinine assay compared very well with the eCREA (r=0.99; new=1.01*old-0.29). Within run precision at 1.02 mg/dL and 4.32 mg/dL had a CV of 1.06 and 0.39 % respectively. The precision profile demonstrated a CV of 18.9% at 0.11 mg/dL. The analytical measurable range was validated between 0.14-20 mg/dL with an average recovery of 98.4%. Linearity average recovery was 98.6%. Correlation of the eGFR using the MDRD or the modified MDRD was good (new=1.15*old-0.15; R2=0.94, figure). Conclusions: The new eCREA Dimension Vista and eGFR correlate well with the method and calculations currently used. Using the standardized method, our laboratory will be able to report the eGFR according with the NKDEP recommendations.

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Evaluation of Total Bilirubin Assay on the GEM Premier 4000 D. J. Dietzen1, T. R. Wilhite2, P. V. A. Pamidi3. 1Washington University School of Medicine, St. Louis, MO, 2St. Louis Children’s Hospital, St. Louis, MO, 3Instrumentation Laboratory, Bedford, MA,

Background: Unconjugated hyperbilirubinemia in newborns may lead to irreversible brain damage (kernicterus). Total bilirubin concentrations dictate the need for intervention (phototherapy, exchange transfusion) aimed at preventing neurological damage. The use of serum or plasma to measure bilirubin is complicated by limited availability of blood and high hematocrits characteristic of newborns. Alternatively, direct bilirubin may be measured in small volumes of whole blood by multiwavelength spectrophotometry. The aim of the current study was to compare the analytical performance of total bilirubin measurement on the Instrumentation Laboratory GEM Premier 4000 to that on the Radiometer ABL 800. Methods: Excess heparinized blood from 100 neonates (age <60 days) and 100 adults was obtained from St. Louis Children’s Hospital and Barnes-Jewish Hospital, respectively. Split samples were analyzed within 10 minutes of each other on the ABL 800 and GEM 4000 platforms. Imprecision was monitored through intelligent quality management (iQM) on the GEM and daily controls on ABL. Results: Imprecision of controls over the three weeks of the study on the ABL was 3.3%, and 3.1% at 4.5 and 19.4 mg/dL, respectively (n = 117). Drift using iQM on the GEM did not exceed 0.05 mg/dL for the process checks at 10.4 mg/dL (n = 150) and 20.1 mg/dL (n = 50). Whole blood bilirubin concentrations ranged from undetectable to 45.6 mg/dL. The initial comparison revealed four significant outliers that were reconciled following a revised correction for turbidity on the GEM. Linear regression of the GEM vs. ABL (see Figure) yielded the following: GEM = 1.034 (ABL) -0.41, r = 0.997, Syx

= 0.84. Bias between the GEM and the ABL averaged -0.1 mg/dL (range -4.2 to 3.6 mg/dL). Conclusions: GEM Premier 4000 shows substantially equivalent performance to the ABL 800 series in assessing the total bilirubin levels in both newborns and adults.

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An LC-MS Method for the Quantification of 4 Bile Acid Species in Broncheal Washings from Lung Transplant PatientsA. N. Sireci, T. Thomas, B. Aramini, F. D’Ovidio, M. A. Pesce, S. Cremers. Columbia University Medical Center, New York, NY,

Context: Micro-aspiration may be a risk factor for the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation. Total bile acids (TBA), measured by a spectrophotometric assay, in bronchial washings obtained during surveillance bronchoscopy are promising biomarkers in predicting outcomes in lung transplantation patients(1). However, little is known about which bile acid species are important in disease pathogenesis.Objectives: To develop an LC-MS method for separating and quantifying 4 major bile acids species in bronchial washings from lung transplant patients.Methods: Standard solutions of three primary bile acids (cholic acid (CA), deoxycholic acid (DCA) and chenodeoxycholic acid (CDCA)) and one taurine conjugate (taurocholic acid (TCA)) were prepared in methanol. Bronchial washings found to be negative by an enzyme-based spectrophotometric assay for TBA (Trinity Biotech. Bray, Ireland) were spiked with standards, deproteinized with acidic methanol, redissolved in 55:45 (v/v) methanol: 0.01% acetic acid containing 0.05% ammonium acetate and subjected to LC-ESI(-)-MS (Waters Quattro Micro) in Selective Ion Recording mode over 14 minutes. The mobile phase was a gradient of water:methanol, both containing 0.5% formic acid and

A76 CLINICAL CHEMISTRY, Vol. 56, No. 6, Supplement, 2010

Tuesday, July 27, 2:00 pm – 4:30 pm Electrolytes/Blood Gas/Metabolites

done. Each analyte was measured on both instrument types in at least 30 serum samples covering the measuring interval.Results: Within each instrument type, individual instrument means and CVs were comparable, and individual instrument results and pooled results within an instrument type were evaluated. Repeatability and reproducibility of 18/27 analytes on Vista met minimal performance criteria; reproducibility for albumin, amylase, iron, LDL-cholesterol, magnesium, total bilirubin and total protein was better on Vista; alkaline phosphatase, AST, calcium, chloride, creatinine, glucose, HDL-cholesterol, lipase, phosphate, total CO2, triglycerides and uric acid were more reproducible on Vitros; ALT, BUN, cholesterol, CK, GGT, LDH, potassium and sodium had equal reproducibility. Of the 9 analytes not meeting the proposed analytical goals for reproducibility on Vista, alkaline phosphatase and creatinine did meet their goal on Vitros. Reproducibility on Vista was problematic for creatinine (Jaffé, low level CV 10,5%) and chloride (3 levels, CV 2.3% - 3.5%). Pearson correlation coefficients between Vista and Vitros ranged from 0.961 to 0.998; r was > 0.990 for 13 analytes. For evaluating the degree of agreement, Bland-Altman plots were drawn and Passing-Bablok regression was used to determine proportional and constant bias via, respectively, slopes and intercepts of the regression lines. BUN, cholesterol, glucose, iron and sodium showed close agreement between both instrument types. Significant deviation from the target value of 1.00 for slopes was observed for 19 analytes (P < 0.05). The slope for LDH (0.39) showed a large deviation from 1.00. Significant deviation from the target value of 0.00 for intercepts was observed for 18 analytes (P < 0.05).Conclusion: although reproducibility was better on Vitros, over-all imprecision of Vista instruments is acceptable for routine use, but extra attention will be needed with regard to daily QC and follow-up. Some methods need improvement. Vista and Vitros results were well correlated, but the numerical values can differ considerably.

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Novel one-shot reagent for colorimetric measurement of sodiumI. Mueller1, R. A. Kaufman2, P. Schu1, J. Schrantz1, E. Metzmann1, T. Hektor1. 1DiaSys Diagnostic Systems GmbH, Holzheim, Germany, 2Specialty Assays, Inc., Hillsborough, NJ,

Sodium is the third-most frequent inorganic ion in the human body after calcium and potassium. Sodium ions are necessary for regulation of blood and body fluids, transmission of nerve impulses, heart activity, and certain metabolic functions. Therefore, plasma sodium concentrations are an important emergency parameter in the clinical laboratory. The normal sodium concentration in the serum is about 135 to 155 mmol/L. Two electrolyte disturbances are known: severe hypernatremia (elevated sodium level in the blood by dehydration) at > 158 mmol/L, severe hyponatremia (medical illnesses in which fluids rich in sodium are lost by vomiting or diarrhea, e.g.) at < 120 mmol/L. There are two established ways for the measurement of sodium: the atomic absorption spectroscopy (advantage: reference method, high accuracy; disadvantage: low throughput) and the ion selective electrode (advantage: high throughput; disadvantage: high maintenance effort).We developed a new liquid-stable one-shot-reagent for the determination of sodium in serum and plasma to be used in small and medium sized laboratories on photometers or small routine photometric analyzers which lack an ISE. The new approach uses the complexation of sodium with the chelator 3,6-bis[(o-phosphonophenyl)azo]-4,5-dihydroxy-naphtalen-2,7-disulfonic acid (Phosphonazo ΙΙΙ). Phosphonazo ΙΙΙ is a phosphorous analog of Arsenazo III wherein the two arsenite groups have been substituted by phosphonate. The complexation causes a change in the Phosphonazo ΙΙΙ spectrum which can be measured by an absorption increase at 660 nm. Phosphonazo ΙΙΙ forms complexes with several mono- and divalent metal ions. The specificity for sodium has been achieved by choosing alkaline buffer conditions. The application on a routine Hitachi 917 analyzer requires a sample volume of 2 μL which is followed by the addition of 180 μL of reagent. After incubation for 4 minutes at 37 °C the complexation reaction is completed and a one point measurement is taken. The absorbance increase of the measurement is linear proportional to the sodium concentration in the sample. The CV (%) for the precision in series (CLSI guideline EP5-A2) for a patient in the physiological range is 1.19 % within run, 0.60 % between day, 0.89 % between run and 1.61 % total precision. Linearity is given from 40 to 180 mmol/L sodium. No interference is observed at bilirubin concentrations up to 20 mg/dL, triglycerides up to 2000 mg/dL, ascorbate up to 30 mg/dL, haemoglobin up to 1000 mg/dL, potassium from 3.9 to 7.7 mmol/L, and magnesium from 0.76 to 7.7 mmol/L. A method comparison of Sodium Phosphonazo ΙΙΙ assay against flame atomic absorption spectroscopy with n=50 patient samples showed a correlation coefficient of r=0.90 and a slope of y=1.00 between the two methods. Our results demonstrate, that the colorimetric Sodium Phosphonazo ΙΙΙ assay offers a suitable photometric method for small and medium-sized laboratories which can be used manually as well as on routine clinical analyzers with a similar performance as ISE and AAS.

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Closing the Gap: Correlation of D-lactate with Anion Gap and Metabolic Acidosis in Diabetic KetoacidosisQ. H. Meng1, J. Lu2, G. Zello1, E. Randell3, K. Adeli4, J. Krahn1. 1University of Saskatchewan, Saskatoon, SK, Canada, 2Wenzhou Medical College, Wenzhou, China, 3Memorial University of Newfoundland, St Johns, NL, Canada, 4University of Toronto, Toronto, ON, Canada,

Objective: Diabetic ketoacidosis (DKA) is a severe acute complication of diabetes. Methylglyoxal is an intermediate glucose metabolite and markedly increased in diabetes. D-lactate is an intermediate metabolite of methylglyoxal. A high anion gap in DKA suggests that some unmeasured anions must contribute to the generation of the anion gap in addition to the ketone bodies. This study was to investigate the correlation of D-lactate with methylglyoxal, metabolic acidosis and anion gap in DKA.Subjects and Methods: In this study, 48 diabetic patients without ketoacidosis (Diabetes), 47 patients with DKA and high anion gap and 43 healthy controls were included. Plasma methylglyoxal was assayed by liquid chromatography-mass spectrometry. Plasma D- and L-lactate were quantitated by high-performance liquid chromatography. Plasma glucose, β-hydroxybutyrate, bicarbonate, electrolytes and blood hemoglobin A1c (HbA1c) were determined on the chemistry analyzers in the clinical biochemistry laboratory.Results: The plasma fasting glucose levels, β-hydroxybutyrate and blood HbA1c in DKA were significantly higher than in the Diabetes and in the controls (P < 0.001). The plasma MG levels in the DKA were highly elevated compared to the Diabetes and to the controls (325.41 ± 140.62 vs. 147.70 ± 59.26 and 325.41 ± 140.62 vs. 169.80 ± 93.67 nmol/l, respectively, P < 0.001). Plasma bicarbonate levels were significantly decreased in DKA compared to the Diabetes or to the control group (13.7 ± 5.9 vs. 26.4 ± 2.5 and 13.7 ± 5.9 vs. 27.8 ± 1.6 mmol/L, respectively, P<0.001). Furthermore, plasma anion gap was significantly increased in DKA compared to the Diabetes and to the control group (20.6 ± 6.4 vs. 6.5 ± 1.8 and 20.6 ± 6.4 vs. 7.5 ± 1.9, respectively, P < 0.001). Plasma L-lactate levels were elevated in DKA (2.14 ± 2.18 mmol/L). Most importantly, plasma D-lactate levels were markedly increased in DKA compared to the Diabetes and to the control groups (3.82 ± 2.50 vs. 0.25 ± 0.35 and 3.82 ± 2.50 vs. 0.47 ± 0.55 mmol/L, respectively, P < 0.001). In addition, plasma D-lactate levels in Diabetes were higher than in the controls. Regression analysis showed that both D- and L-lactate were associated with acidosis (bicarbonate). Further multiple linear regression analysis demonstrated that D-lactate, but not L-lactate was correlated with anion gap and an independent predictor of anion gap (r = 0.686, P < 0.001, n = 80). The contribution of D-lactate to diabetic acidosis and anion gap was almost equivalent to β-hydroxybutyrate. A positive correlation between plasma D-lactate and methylglyoxal levels was also observed (r = 0.309, P < 0.02, n = 80).Conclusions: Our study demonstrates that plasma levels of glucose, methylglyoxal, β-hydroxybutyrate and blood HbA1c in DKA are significantly increased. Moreover, plasma D-lactate levels in DKA are highly elevated and make significant contributions to the metabolic acidosis and the high anion gap in DKA. There is a positive correlation between plasma methylglyoxal and D-lactate levels. Laboratory monitoring of D-lactate levels will provide a significant value for DKA and should be implemented in laboratory service.Keywords: Diabetes, diabetic ketoacidosis, anion gap, methylglyoxal, D-lactate

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Imprecision Study of Dimension Vista and Comparability with Vitros 5,1 FSD. Coenen, V. Verhaeghen, K. Van Brussel, V. Van Hoof. Antwerp University Hospital, Edegem, Belgium,

Objective: Dimension Vista® 1500 (Siemens, Newark, DE) instruments, linked to an Advia LabCell® (Siemens) system, will replace Vitros® 5,1 FS (Ortho-Clinical Diagnostics, Rochester, NY) instruments as part of a total laboratory automation project in our hospital. Vista integrates four technologies (photometry, electrolyte detection, nephelometry, chemiluminescence). Here, we describe validation results on Vista and the comparability with Vitros for 27 common biochemical analytes in serum.Methodology: Three Vista instruments were validated and compared with three Vitros instruments. Repeatability (within-run precision) was carried out on Vista by analyzing ten replicate samples of control material (Multiqual, Bio-Rad, Hercules, CA) at three concentrations. Reproducibility (within-laboratory precision) was studied on both Vista and Vitros by analyzing control material (Multiqual, Bio-Rad) at three concentrations twice daily for ten days on all instruments. Means and CVs for each individual instrument and for each type of instrument were calculated. For Vista, these estimates of precision were compared with analytical goals defined by the minimum performance for imprecision based on a biological variation database (Ricos). Reproducibility estimates were compared for both types of instruments. For evaluating the degree of correlation and agreement between Vista and Vitros, a comparison of patient samples experiment was

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hours, 4-6 hours, 6-8 hours, 8-10 hours and 10-12 hours. The SDDs were then regressed against the midpoint time intervals of 1 to 11 hours; extrapolation to zero time (y-intercept) represents the average variation (s

a2 + s

b2)1/2.

Results The Table summarizes our findings.Conclusions The Rapidpoint offered better performance for sodium and potassium. The performance of these two iSTAT analytes is roughly equal to that offered by central laboratory analyzers like the Roche Hitachi 917 and the Beckman LX-20.

TestRapidpoint Pairs (12 h)

SDD at t = 0 (WPI), Rapidpoint

iSTAT Pairs (12 h)

SDD at t = 0 (WPI) iSTAT

Diff (Rapidpoint-iSTAT)

Glucose, mmol/L 3162 0.8162

Potassium, mmol/L

3783 0.2235 1117 0.3009 -29.5%

Sodium, mmol/L 3975 1.0928 1284 1.3899 -23.9%

HCO3-, mmol/L 3593 1.415

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Dialysate Method Comparison Using the Dialysate Sample Mode on the RAPIDPoint® 350 Blood Gas AnalyzerT. Hotaling. Siemens Healthcare Diagnostics Inc., Norwood, MA,

Background: Dialysis treatment in renal patients replaces the filtration function of the kidneys. Dialysate is the aqueous chemical solution used in conjunction with a filter to remove waste products and excess fluid from the bloodstream while maintaining proper electrolyte balance. Dialysate can be either bicarbonate or acetate based and is normally prepared by mixing appropriate concentrations of the substance(s) with distilled water. Measuring the dialysate fluid components aids in verifying and controlling the electrolyte concentrations in the dialysis liquid, most significantly those of Na+, K+, and Ca++. Presented is a method comparison of the new dialysate measurement option under development for selected markets on the RAPIDPoint 350 blood gas analyzer.Method: Bicarbonate-based dialysate samples from five sources and acetate-based dialysate samples from a single source were prepared, encompassing the entire reporting range for each parameter. The specimens were measured in triplicate in the dialysate sample mode on multiple RAPIDPoint 350 systems. The same specimens were immediately measured on a reference or comparative device. Six RAPIDPoint 350 units were used to analyze Na+, K+, pH, and pCO

2; three devices were used to analyze Ca++.

Flame photometry was used as the reference method for Na+ and K+, while Ca++, pH, and pCO

2 were compared against the RAPIDLab® 348 (RL348) system.

Results: Simple linear regression of the grouped data was employed to determine the method comparison statistics on each of the measured parameters for both the bicarbonate- and acetate-based material (see table).Conclusions: Dialysis fluid measurement on the RAPIDPoint 350 system showed good correlation to reference and comparative methods, particularly for Na+, K+ and Ca++. It affords the clinician the ability to verify dialysate composition and/or monitor the patient’s whole blood electrolytic balance on a single portable device.

Table 1. RAPIDPoint 350 dialysate mode method comparison summary.

Analyte Fluid Method n r2 Slope Intercept

Na+ Bicarb Flame 1620 0.999 0.999 +0.101

K+ Bicarb Flame 1620 0.999 0.999 +0.004

Ca++ Bicarb RL348 810 0.991 0.994 +0.013

pH Bicarb RL348 1260 0.984 0.983 +0.121

pCO2

Bicarb RL348 1260 0.997 0.997 +0.200

Na+ Acetate Flame 324 0.999 1.012 -0.942

K+ Acetate Flame 324 0.996 0.990 +0.025

Ca++ Acetate RL348 162 0.986 0.995 -0.003

pCO2

Acetate RL348 252 0.997 1.088 -7.896

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Comparability of Test Results and Sigma Metrics for the Abbott ARCHITECT Family of Clinical Chemistry and Immunoassay Systems A. DeFrance, C. Lo, D. Armbruster, Y. Lemma, D. Petty, T. Sparks, J. Browning. Abbott Laboratories, Irving, TX,

Objective: Nine clinical chemistry analytes and one immunoassay analyte were tested for patient result comparability across three ARCHITECT clinical chemistry and two immunoassay systems. Twenty day precision and patient method comparison against a

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Analytical Performance of Ion Selective Electrode (ISE)

On Beckman Coulter AU5800® Clinical Chemistry Analysers*S. O’Mahoney1, M. Kono2, A. Fujimura1, J. Siegele1, M. O’Neill1, M. D. McCusker1. 1Beckman Coulter Inc., Co. Clare, Ireland, 2Beckman Coulter Inc., Shizuoka, Japan,

Background: The Beckman Coulter AU5800 clinical chemistry analyser is the latest system from Beckman Coulter. It is a fully automated, random access analyser, designed for ultra high throughput laboratories. This system is designed to suit varying workloads and is available in different configurations, from a one-photometric module AU5810, up to a four-photometric module AU5840. Electrolyte measurement is performed using a single or double cell Ion Selective Electrode (ISE).Methods: The single cell option processes 300 serum samples/hour, the double cell option processes 600 serum samples/hour. Indirect measurement of sodium, potassium and chloride is performed using electrode technology which is in common with other members of the AU family. This study evaluated the analytical performance of sodium, potassium and chloride in serum and urine on 2 double cell AU5800 ISE units. Each double cell contains 2 individual ISE flow cells, which are used alternately during sample testing.Results: The analytical performance for one double flow cell is presented in the table below, where within-run precision, accuracy of each flow cell and recovery difference between each flow cell are illustrated. Total precision (CLSI EP-5A) met the acceptance criteria and method comparison/bias estimation (CLSI EP-09) against the AU5400 ISE system confirmed substantially equivalent data performance. Linearity (CLSI EP-6) was tested using the following ranges: sodium serum from 50-200mEq/L, sodium urine from 10-400mEq/L, potassium serum from 1.0-10.0mEq/L, potassium urine from 2.0-200mEq/L, chloride serum from 50-200mEq/L, chloride urine from 15-400mEq/L. Based on the ranges specified, linearity testing confirmed reportable ranges for each electrolyte.Conclusions: This study confirms equivalent precision and accuracy performance of the AU5800 ISE compared to other AU systems. Analysis of the AU5800 ISE performance test data demonstrates the ISE reliability and consistency.

SerumN=20

Target(mEq/L)

Within Run Precision (% CV’s)

Accuracy vs Target(mEq/L)

Recovery Difference Between Cells(mEq/L)

Cell 1 Cell 2 Cell 1 Cell 2

Na118 0.32 0.42 0.43 0.30 0.14

152 0.21 0.16 1.10 0.00 1.10

K3.81 0.39 0.40 -0.02 -0.03 0.01

6.36 0.33 0.32 0.07 -0.05 0.12

Cl89.9 0.32 0.29 0.10 -0.26 0.36

118 0.24 0.17 0.94 -0.43 1.37

* Analyser under evaluation and currently not available for clinical use.

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Use of serial ICU patient data to evaluate the goodness of iSTAT and RapidPoint electrolyte testingG. S. Cembrowski1, R. B. Schifman2, D. V. Tran1. 1University of Alberta Hospital, Edmonton, AB, Canada, 2Southern Arizona VA Health Care System, Tuscon, AZ,

Background Method stability and analytical imprecision are two of the most important criteria for instrument selection. We have devised a data-mining statistic (within-patient imprecision [WPI] regressed to zero-time between specimens) that summarizes the average short term analytic imprecision (s

a) and minimizes biologic patient variation (s

b).

Unlike the short term analytic imprecision that is derived from quality control data, this statistic can summarize the analytic imprecision over many reagent lots and calibrations. Acute care hospitals and intensive care units provide adequate data to generate this imprecision statistic. This statistic can be used to compare the analytic performance of different analyzers operating in similar patient care environments.Methods We analyzed 18 and 22 months of serial patient Rapidpoint 400(Siemens, Deerfield IL) and iSTAT (Abbott, Abbott Park, IL) results, respectively, operated by nurses and respiratory therapists in intensive care units at the Tucson VA Hospital. For sodium and potassium (done by both iSTAT and Rapidpoint) and bicarbonate and glucose (done only by Rapidpoint), we tabulated the measurements of paired intra-patient samples drawn within 12 hours of each other. After outlier removal, we calculated the standard deviations of duplicates (SDD) of the intra-patient pairs grouped in two-hour intervals: 0-2 hours, 2-4

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platelet collections. The pH of platelet collections is occasionally used as a quality control measure for blood banking, where platelets with a pH <6.2 are considered unusable due to presumed contamination. Pleural fluid pH is used to identify parapneumonic effusions that require draining, where a pH <7.2 indicates drainage is required.Objectives: The goals of this study were 1) to evaluate the ability of the Radiometer ABL800 series to measure pleural fluid pH using the dedicated pleural fluid pH measuring mode; 2) to validate pH measurement of platelet collections using the ABL835 FLEX.Material and Methods: Pleural fluid: Thoracocentesis specimens were collected from 25 different patients and stored at -20°C. For analysis, samples were thawed at 4°C and then spiked with acetic acid to yield a total of 45 specimens spanning a pH range of 6.95-7.60. The pH of each specimen was measured in duplicate using Radiometer ABL835 and ABL837 analyzers and compared against an FDA 510(k)-approved reference instrument (Roche Omni S). The Radiometer dedicated pleural fluid pH measuring mode is traceable to the IFCC reference method for measuring pH. Whole blood specimens and liquid controls were also compared between the instruments. Platelets: The pH of 20 different platelet collections was measured using the Radiometer ABL835 and compared with a pH meter (accumet XL15, Fisher Scientific) as the reference method. Measurements were done in duplicate within 2 minutes of each other using syringe-drawn aliquots from platelet collection bags. Results of pleural fluid and platelet experiments were analyzed using Deming regression and Bland-Altman difference plots.Results: Regression analysis indicated that the Radiometer ABL800 series had proportional and constant bias (y=1.3 - 2.2) in comparison to the Roche Omni S. At pH 7.4, values were identical, whereas at pH <7.2 the ABL800 series were ~0.1 units lower. Analysis of liquid controls revealed a similar difference (y=1.1 - 0.6) between the ABL800 series and Omni. There was good agreement between the Omni and ABL800s for whole blood pH measurements (y=1.0 - 0.5). For platelet pH determination, the pH meter and ABL835 blood gas analyzer demonstrated excellent agreement (y=1.0 - 0.2).Discussion: The results of this study demonstrate constant and proportional differences between the Roche Omni reference pleural fluid pH method and the Radiometer 800s. Clinically, these differences are acceptable for pleural fluid analysis as there was no significant difference between instruments as to whether patients would be treated or not (pleural effusion drainage) using the standard pH 7.2 cutoff. The observed differences in pleural fluid pH measurement likely reflect differential handling of liquid specimens between the Roche Omni and the ABL800 series; these differences were evident when comparing liquid controls, but not whole blood specimens. This study confirms the validity of the Radiometer ABL800 series blood gas analyzers to measure platelet and pleural fluid pH.

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Next Generation Magnesium Assay Application for the Abbott ARCHITECT® cSystems™J. Salazar, C. Kasal, B. Combs, L. Harris. Abbott Diagnostics, Irving, TX,

Background: Magnesium is an essential nutrient involved in many biochemical functions. Hypomagnesemia results in the impairment of neuromuscular function and may develop in severe prolonged diarrhea, malabsorption syndromes, hyperaldosteronism, and diuretic therapy. Hypermagnesemia is seen in renal failure and diabetic coma. The Abbott Next Generation Magnesium assay uses an Enzymatic methodology, and is standardized to the National Institutes of Standards and Technology (NIST) standard reference material (SRM) 956. Next Generation Magnesium is a liquid-ready-to-use, 2-part reagent, which will be available in two kit sizes.Methodology: Magnesium is measured by the use of the enzymatic reaction with Isocitrate Dehydrogenase. Magnesium present in the sample is a cofactor for the reaction. The reaction is monitored via the formation of NADPH. The rate of increase in absorbance at 340nm, due to the formation of NADPH, is directly proportional to the magnesium concentration in the sample.Objective: Assay was evaluated on the Abbott ARCHITECT cSystems for the quantitation of magnesium in human serum, plasma, and urine. The calibration and on-board stability will be a minimum of 30 days. The serum application will achieve the performance requirements of Total Error </=15.0%, Bias </=7.5%, and Total Precision (%CV) </=3.75%, per the equation %Total Error (TE) = %Bias + 2xTotal Precision.Representative performance data for key attribute serum testing are summarized below.

reference system was performed and Six Sigma metrics were calculated.Methodology: The ARCHITECT Clinical Chemistry (c4000, c8000 & c16000) and Immunoassay (i1000SR & i2000SR) Systems use identical reagents and methods, are fully automated, and can be operated as stand-alone instruments or integrated systems. The same set of fresh patients were tested for nine clinical chemistry analytes on the three chemistry analyzers and one immunoassay analyte on the two immunoassay analyzers to demonstrate equivalent results across systems. Twenty day precision was measured for each system using the same controls. Method comparison against a reference system was performed by testing the same patient specimens. Results were used to calculate Sigma metrics.Results: Results were compared by calculating the grand mean for each analyte across three platforms for clinical chemistry assays and two platforms for immunoassay. The individual platform means were then compared to the grand mean. In addition, minimum and maximum differences for each individual sample for each analyte on each system were determined. Sigma metrics for assays with comparable methodologies between ARCHITECT and the reference system consistently demonstrated high analytical quality for the clinical chemistry assays.

Comparison of Patient Results Across a Family of Systems

AssayGrand Mean Result

c4000 c8000 c16000 Range of Samples(N)

Min to Max diff

% diff*

Sigma Value**

% diffSigma Value

% diffSigma Value

Urea Nitrogen (mg/dL)

35.4 1.76 8.3 -0.53 15.5 -1.23 13.95.3-112.4(41)

0.0-3.8

Magnesium (meq/L)

1.68 0.86 NC 2.11 NC -2.97 NC0.2-2.5(40)

0.0-0.11

Calcium (mg/dL) 8.7 0.56 9.8 0.06 10.4 -0.62 10.87.0-10.7(39)

0.0-0.23

CO2 (meq/L) 18.6 -1.58 NC -1.79 NC 3.36 NC7.7-28.7(43)

0.01-1.15

Creatinine (mg/dL)

1.87 -0.55 6.4 1.96 6.1 -1.41 9.60.57-11.75(41)

0.0-0.25

Glucose (mg/dL) 120.0 -0.01 19.8 0.12 15.8 -0.11 13.219-344(40)

0.0-1.5

Sodium (mmol/L) 142.3 0.32 8.9 -0.64 6.5 0.32 9.3129.2-166.0(41)

0.1-4.2

Potassium (mmol/L)

4.47 0.99 6.6 -1.22 9.4 0.23 10.43.1-6.2(40)

0.01-0.17

Chloride (mmol/L)

109.0 0.63 9.8 -0.25 5.3 -0.38 13.997.7-137.9(41)

0.02-3.56

i1000sr i2000sr% diff*

Sigma Value% diff*

Sigma Value

TSH (ng/mL) 4.27 -0.92 NC 0.92 NC0.02-42.1(38)

0.0-0.61

*% diff = difference between Grand Mean and individual systems means**Sigma Values calculated using bias from reference instrument and twenty day precision.NC -Not Calculated - Sigma values were not calculated for assays using a different methodology from ARHCITECT.

Conclusion: The ARCHITECT Clinical Chemistry and Immunoassay Systems Family demonstrated result comparability and excellent Six Sigma performance when compared outside of the ARCHITECT family of systems to a commercially available reference system. Patient specimens may be tested for the same analyte on any ARCHITECT system interchangeably and equivalent results will be obtained. The ability to integrate ARCHITECT clinical chemistry and

immunoassay modules provides the capability to

perform testing for most routine analytes on one system.

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Validation of platelet collection and pleural fluid pH using the Radiometer ABL800 series blood gas analyzers.C. R. McCudden1, C. M. Parker2, S. Koenig2, Y. A. Park1. 1University of North Carolina, Chapel Hill, NC, 2University of North Carolina Hospitals, Chapel Hill, NC,

Background: Laboratories frequently receive requests to analyze non-standard specimens for clinical purposes. Many of these specimens are rare or variable making it challenging to validate their measurement. This study focused on pH determination of pleural fluid and

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Sample number

1 12 3 4 10 5 8 11 13 6 9 2 14 7

m+2sd 1.09 1.20 1.15 1.31 1.72 1.35 1.47 1.53 1.68 1.83 2.14 1.99 2.32 2.49

mean 0.81 0.86 0.93 1.01 1.06 1.07 1.19 1.29 1.34 1.55 1.62 1.77 2.04 2.19

m-2sd 0.53 0.52 0.71 0.71 0.40 0.79 0.91 1.05 1.00 1.27 1.10 1.55 1.76 1.89

sd 12.82 19.34 6.64 11.4 29.26 8.8 11.5 10.9 12.08 9.6 14.14 8.5 9.1 7.9mean absolute (%) difference

11.36 13.75 8.57 10.04 12.75 9.25 11.1 10.5 9.61 8.41 7.8 7.4 7.1 6.9

Number of labs with bias>15% from consensus mean

56 84 41 51 53 53 42 44 49 32 21 26 28 30

(%) 21.05 31.58 15.42 19.18 19.93 19.93 15.79 16.54 18.42 12.03 7.89 9.77 10.53 11.28

The samples were prepared from pooled human sera from donors by MCA-unit (Queen-Beatrix hospital, Netherlands). Reported values were subjected to a 3-SD test for the elimination of outliers and less than 5 labs were removed. The mean bias of all participating labs ranged from 7.9 to 32.6 in all samples, but only from 12.3 to 19.9 in the region of measurements within the critical range. The number of laboratories that deviated more than 15% in this area ranged from 32 to 52. Our preliminary results cannot support the reporting of eGFR based on these creatinine measurements and we must support the current effort of IFCC and IVD manufacturers to better harmonize creatinine measurements.

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Development of an Enzymatic Creatinine Assay on the Dimension Vista® Intelligent Lab System from Siemens Healthcare DiagnosticsS. T. Salyer, J. Strauss, C. R. Jesse. Siemens Healthcare Diagnostics, Newark, DE,

Introduction and Objective: We describe the development and analytical performance of a fully automated assay for the measurement of creatinine in serum, plasma, and urine on the Dimension Vista® System using our enzymatic method. Our objective was to develop a standardized creatinine assay which has improved precision and accuracy. Relevance: This assay addresses healthcare providers need for standardized creatinine measurement which is necessary to diagnose and treat renal disease. Method: This method is based on the determination of sarcosine after conversion of creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured photometrically at 540nm via a modified Trinder reaction. The new assay is traceable to isotope dilution mass spectrometry (ID-MS). The enzymatic creatinine calibrator is traceable to working standards prepared with National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 914 and the assigned values are confirmed using NIST SRM 967 material, whose values are assigned by ID-MS. The method uses a 2.7ul sample size. Results: Time to 1st result is 7.7 minutes and calibration is stable for 90 days. The assay range for serum and plasma is 0.14 to 20.0 mg/dL; for urine the assay range is 2.8 to 400 mg/dL. Samples above the assay range can be quantitated using the onboard auto-dilution feature. Limit of detection is 0.14 mg/dL. Repeatability and within-lab reproducibility on serum pools were measured to be 2.9 and 4.4 %CV at 0.61 mg/dL, and 1.4 and 2.4%CV at 1.57 mg/dL creatinine respectively per the CLSI EP5-A2 protocol over a 20 day testing interval. Recovery of NIST 967 material (levels 1 and 2) is within 5% of the NIST certified values. Split sample correlation (n=130) between the Dimension method (DV) and Roche CREA plus® kit run on Hitachi 717 Analyzer gave a Deming regression fit as follows: slope = 1.03, intercept = -0.18, and correlation (r) = 1.00. The correlation study included serum and plasma samples which were visibly lipemic and icteric. The Deming regression for a split sample study with urine is: slope = 1.06, intercept = -6.11, and correlation = 0.99. No significant interference (<10%) at a creatinine concentration of 1.02 mg/dL is found at 30 mg/dL bilirubin, 1000 mg/dL triglyceride, 500 mg/dL hemoglobin, or 25 mg/dL creatine. Conclusion: We conclude that the new standardized enzymatic creatinine assay has excellent precision, accuracy, and a dynamic range suitable for measurement of creatinine in serum, plasma, and urine.

Study Protocol Results* (mg/dL)

Calibration/On-Board Stability

% Recovery to Day 0 Minimum of 30 days

Bias

% Difference to SRM 956c CofA Target Values, Levels 1, 2, & 3

Target: 3.031 mg/dL Reagent Lot1: -0.4%Reagent Lot2: -0.4%Reagent Lot3: -0.7%

Target: 2.084 mg/dLReagent Lot1: -0.7%Reagent Lot2: -0.2%Reagent Lot3: -0.2%

Target: 1.143 mg/dLReagent Lot1: 1.5%Reagent Lot2: 3.2%Reagent Lot3: 1.5%

PrecisionCLSI EP10-A2(5-day, N=50)

Mean: 1.58 mg/dLWithin Run 0.88%CV; Total 1.56%CVMean: 3.82 mg/dLWithin Run 0.49%CV; Total 1.33%CV

Linearity CLSI EP6-A 0.60 - 20.00 mg/dL

Sensitivity CLSI EP17-ALimit of Detection (LOD)0.15 mg/dL

Limit of Quantitation (LOQ)0.60 mg/dL

Interference:BilirubinHemolysisLipemia

Dose Response,Serum MgLevels 1, 2, & 3

Target: 1.69 mg/dL60 mg/dL Conj Bili: 94%60 mg/dL Unconj Bili: 102%

Target: 3.35 mg/dL60 mg/dL Conj Bili: 94%60 mg/dL Unconj Bili: 101%

Target: 5.63 mg/dL60 mg/dL Conj Bili: 94%60 mg/dL Unconj Bili: 101%

Target: 1.52 mg/dL500 mg/dL Hb: 105%

Target: 2.98 mg/dL500 mg/dL Hb: 102%

Target: 5.07 mg/dL500 mg/dL Hb: 101%

Target: 1.59 mg/dL1000 mg/dL Intralipid: 100%

Target: 3.04 mg/dL1000 mg/dL Intralipid: 100%

Target: 5.26 mg/dL1000 mg/dL Intralipid: 100%

*In developmentConclusion: The Next Generation Magnesium assay on the Abbott ARCHITECT cSystems provides an Enzymatic method, standardized to NIST SRM 956. The reagent is a liquid-ready-to-use 2-part format with an extended calibration/on-board stability of at least 30 days. Representative data indicates excellent assay performance with </=3.2 %Bias, </=1.56 Total %CV, and 0.60 - 20.00 mg/dL linearity. Study also supports robustness against common interferents such as bilirubin up to 60 mg/dL, hemoglobin up to 500 mg/dL, and intralipid up to 1000 mg/dL.

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Variations in the serum Creatinine determinations in Greek laboratories. - Impact on GFR estimation (eGFR).K. Makris1, I. Drakopoulos1, O. Panagiotakis2, D. Rizos3, A. Haliassos4. 1Clinical Biochemistry Department, KAT Hospital, Kifissia, Greece, 2ESEAP, Athens, Greece, 3Hormone Laboratory “Aretaieion” University Hospital, Athens, Greece, 4Diamedica SA, Athens, Greece,

Glomerular filtration rate (GFR) is the best index of kidney function used to diagnose stage and treat chronic kidney disease. International organizations recommend the use of GFR estimating equations based on serum creatinine measurements and other demographic and clinical variables to assess kidney function. Due to substantial interlaboratory variation creatinine based equations require the calibration of the creatinine assays to be traceable to the laboratory that created the equation, otherwise a systematic bias occurs in the eGFR.In order to access these creatinine calibration variations we used data from the Greek External Quality Assessment Scheme (ESEAP). The number of participating laboratories was 266. The consensus mean was calculated for each sample (ranging from 0.81 to 2.19mg/dL) and the absolute percentage of deviation was calculated for all laboratories.Our goal was to determine the level of accuracy and reproducibility of measurements among Greek laboratories and if this can be tolerated without compromising the clinical utility of the eGFR equation. For this purpose we focus on creatinine range between 1.00 and 1.55mg/dL which corresponds to eGFR values near the therapeutic decision threshold of 60ml/min/1.73m2. The table summarizes our results:

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and relating labor, time, and expense.The performance of the electrolyte analyzer was evaluated with four i-Smart 30 analyzers at i-SENS, Inc. facility in Seoul, Korea. For sodium, potassium, and chloride ions, heparinized whole blood samples were collected from healthy individuals and altered by spiking or dilution technique. For hematocrit, heparinized whole blood samples were centrifuged to separate plasma from red blood cells and the plasma and the red blood cells were re-mixed at appropriate ratios to span the hematocrit range. Whole blood samples were analyzed on the i-Smart 30 analyzers and an ABL 825 blood gas analyzer (Radiometer) for comparison. For hematocrit, the results were also compared to the centrifuged microhematocrit method. A total of 84 whole blood samples were tested in duplicate for electrolyte parameters and a total of 72 samples in duplicate for hematocrit over two weeks of the cartridge uselife. Good agreement was found between the i-Smart and the ABL. The linear regression results yielded a slope of 0.908 with an intercept of 14.2 (r2=0.994) over a range of 120 ~ 180 mM for sodium, a slope of 0.971 with an intercept of -0.07 (r2=0.999) over a range of 2 ~ 13 mM for potassium, a slope of 0.968 with an intercept of -0.5 (r2=0.998) over a range of 90 ~ 170 mM for chloride, and a slope of 0.999 with an intercept of -3.3 (r2=0.987) over a range of 10 ~ 60 % for hematocrit, As compared to the microhematocrit method, a slope of 0.955 with an intercept of -0.6 (r2=0.987) was obtained.In conclusion, the i-Smart 30 electrolyte analyzer shows good correlation in whole blood with the ABL 825 blood analyzer for sodium, potassium, chloride, and hematocrit.

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Correlation Studies Of The Creatinine Enzymatic Method In The Roche Modular® And Roche Cobas® 6000 Analyser SystemsM. F. Aumentado, S. Pang, S. Cosio, A. Omar, M. Wong. Alexandra Hospital, Singapore, Singapore,

Alexandra Hospital is a 400-bed acute care general hospital. The Department of Laboratory Medicine uses two main chemistry analytical platforms, namely the Roche Modular and the Roche COBAS 6000 analysers (Roche Diagnostics, Basel, Switzerland). The COBAS 6000 processes serum, plasma and urine samples while the Roche Modular is designated to run serum and plasma samples only. Our laboratory measures serum/plasma and urine creatinine levels using a modified Jaffé method which has a higher sensitivity and better precision than the original Jaffé method. Creatinine is produced endogenously from creatine and creatine phosphate as a result of muscle metabolic processes and excreted by glomerular filtration during normal renal function. In 2009, Roche introduced an IDMS-traceable enzymatic method, based on the established determination of sarcosine after conversion of creatinine with the aid of creatinase, creatinase and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically. We evaluated the technical performance of this new assay on both analysers. A total of 151 serum/plasma samples were analysed on both instruments while 101 urine samples were analysed on the COBAS 6000 analyser. Imprecision studies using 2 concentrations of material for serum/plasma on the Roche Modular yielded intra-assay CVs of 2.06-2.58% and inter-assay CVs of 0.93-1.67%. The COBAS 6000 yielded intra-assay CVs of 1.35-1.56%, and inter-assay CVs of 1.37-1.59%. The intra-assay and inter-assay CVs for urine samples on the COBAS 6000 were 1.20-1.29% and 1.29-1.75% respectively. Correlation studies between the enzymatic and Jaffé methods on the COBAS 6000 and Roche Modular derived a relationship of y=1.0236x-2.4107 (R2=0.9965) and y=1.0314x-6.0687 (R2=0.998) respectively. Correlation studies on urine samples showed a relationship of y=1.0587x-0.1918 (R2=0.998). The correlation between the two instruments on the other hand yielded a relationship of y=1.0247x-0.4595 (R2=0.9993). We collected serum samples from 199 healthy individuals, comprising 159 females and 40 males, to derive reference ranges in our local population. Female and male reference ranges were 41-79 μmol/L and 64-111 μmol/L respectively. Our study shows that precision studies for the creatinine enzymatic method are acceptable. In addition, the new method correlates well with the creatinine Jaffé method.

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An Automated Turbulent Flow Liquid Chromatography - Isotope Dilution Mass Spectrometry (LC-IDMS) Method for Quantitation of Serum CreatinineR. Harlan1, W. Clarke1, J. M. Di Bussolo2, M. Kozak2, J. Straseski1, D. L. Meany1. 1Johns Hopkins Medical Institutions, Baltimore, MD, 2Thermo Fisher Scientific, Franklin, MA,

Background and Objective: Proper estimation of Glomerular Filtration Rate (GFR) requires accurate measurement of serum creatinine. When creatinine concentrations determined by routine clinical assays are in question, reference measurement procedures

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Assessment of a Whole Blood Neonatal Bilirubin Method on the RAPIDPoint® 405 Instrument versus a Plasma Method on the VITROS® 950 Chemistry SystemT. Hotaling, M. Lynch. Siemens Healthcare Diagnostics Inc., Norwood, MA,

BACKGROUND: In the neonate, bilirubin is measured as an aid for assessing jaundice and the risk of kernicterus. A fast turnaround time on minimal sample volume is often required. We present an initial hospital evaluation of a new whole blood neonatal bilirubin (nBili) method under development for the point-of-care, cartridge-based Siemens RAPIDPoint 405 (RP405) blood gas analyzer compared to plasma nBili analysis on the Ortho-Clinical Diagnostics VITROS® 950 chemistry system.METHOD: Heparinized whole blood specimens from neonates (0-14 days old) were obtained over an 8-day period. Samples from each specimen were spun and measured as plasma on the VITROS system; remnant volume was measured as whole blood on up to two RP405 instruments (n=218). Imprecision was monitored daily on the RP405s using aqueous controls. No adjustments to the RP405 bias to reference correction algorithms were applied at this time.RESULTS: The RP405 total imprecision (%CV) of controls was 3.1%, 2.9%, and 2.9% at 19.8, 9.6, and 5.1 mg/dL (n=26), respectively. Least squares regression comparing the RP405 (without final bias to reference correction) versus the VITROS system yielded a slope of 0.89 and intercept of -0.43, with r=0.973 across the nBili range of 2.1-19.2 mg/dL (see figure). No significant change in RP405 nBili bias was observed as a function of specimen total hemoglobin (tHb; range of 11.6-22.0 g/dL). RP405 nBili bias to reference was also not significantly affected by specimen pH (range of 7.31-7.76). The RP405 system reports nBili results in approximately 1 minute from sample introduction.CONCLUSIONS: The RAPIDPoint 405 whole blood neonatal bilirubin method gives analytical values comparable to those of the VITROS plasma chemistry method without the need for preanalytical centrifugation. It may present a quick time-to-patient-result alternative for monitoring neonatal bilirubin.

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Evaluation of the i-Smart 30 electrolyte analyzer: A smart electrolyte analyzer for point-of-care and laboratory testingJ. Shin1, T. Y. Kang1, H. Kim1, M. Kim1, J. Ha1, H. Nam2, G. S. Cha2. 1i-SENS, Inc., Seoul, Korea, Republic of, 2Kwangwoon University, Seoul, Korea, Republic of,

The i-Smart 30 analyzer, developed by i-SENS, is a fully automated electrolyte analyzer that can accurately measure the concentrations of sodium, potassium, and chloride ions and hematocrit in blood for point-of-care and laboratory testing.The analyzer uses 60 μl of whole blood, serum, or plasma for analysis and reports the results in fifty seconds from sample introduction on the color screen of the analyzer. The analyzer offers complete portability with light weight (5.5 Kg) and battery power option (the built-in rechargeable battery allows uninterrupted use without the main power for up to two hours). Further, the analyzer operates on an embedded PC with Microsoft Windows® XP Embedded Operating System and provides many convenient features such as touch screen operation, voice and pop-up instructions, easy data entry using barcode scanner or virtual keyboard on the screen, and USB ports for data download.Besides many advantageous features mentioned above, the i-Smart analyzer is the only electrolyte analyzer available in the market that uses a closed cartridge including electrochemical sensors, calibration solutions, and all fluidic components from a sample introducing probe to a waste bag. This cartridge reduces the maintenances of the analyzer

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aid in investigation. Currently, all creatinine reference measurement procedures require different degrees of clean-up of serum samples before analysis. The clean-up procedures of some methods are so labor-intensive that it may prevent their implementation in a routine clinical laboratory setting. Here, we developed an automated, fast, accurate and reliable turbulent flow liquid chromatography (TFLC) - isotope dilution mass spectrometry (IDMS) method for quantitation of serum creatinine. The novelty of this method lies in the use of TFLC using a cation exchange column for on-line serum sample clean-up to automate serum analysis.Methods: Human serum samples were mixed with an internal standard solution of deuterated creatinine (creatinine-D

3) and were injected onto a Cyclone MCX TurboFlow™

column (0.5 x 50 mm, Thermo Scientific, Franklin, MA). The extracted creatinine and creatinine-D

3 were eluted onto a Hypercarb column (5 μm particle size, 3 x 50 mm,

Thermo Scientific, Bellefonte, PA) and separated using a 5-95% gradient of methanol with 0.1% ammonium hydroxide over 2.5 minutes. Creatinine and creatinine-D

3 were ionized

using electrospray ionization and measured by selective ion monitoring of m/z 114 and 117, respectively, using a TSQ Quantum Access mass spectrometer (Thermo Scientific, San Jose, CA). Precision, linearity, limit of detection (LOD) and limit of quantitation (LOQ) of this TFLC-IDMS method were evaluated. Method comparison between the Roche Creatinine Plus enzymatic assay and this method was achieved using a Deming fit and Bland-Altman analyses on the creatinine results of 134 patients’ serum samples.Results: Precisions of this method were less than 8% (1.0-2.5mg/dL). LOD was 0.05 mg/dL and LOQ was 0.3 mg/dL. Average recovery was 111.0% in the range of 0.41 to 6.5 mg/dL. Creatinine concentration of the National Institute of Standards and Technology (NIST) Standard Reference Material 967 levels 1 and 2TF were 0.77 ± 0.01 mg/dL (mean ± SD,standard deviation, n=3) and 4.01 ± 0.04 mg/dL (n=3), respectively. Based on the Student’s t test, these values were not significantly different from their certified concentrations of 0.75 ± 0.01 mg/dL and 3.92 ± 0.04 mg/dL. Both the Deming fit analysis and Bland-Altman plot indicated that the TFLC-IDMS method and the Roche Creatinine Plus enzymatic assay compared well over the range of 0.33-6.5 mg/dL creatinine (n=134). The Deming fit analysis produced a slope of 1.07 (95% CI 1.05 to 1.09) and an intercept of -0.04 (95% CI -0.07 to -0.01) with Pearson correlation coefficient (r) of 1.00. The Bland-Altman plot demonstrated that 95.5% of the samples (128/134) were within the 95% limits of agreement (-13.0% to 19.4%), which were calculated based on the 2 Standard standard deviation limits of the differences between the methods.Conclusion: We have developed an automated and accurate method for quantitation of serum creatinine. It has demonstrated potential as a quick and simple alternative to current creatinine reference methods.