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Transcript of Nephrolithiasis for the Internist - medicine.uci.edu Rounds... · Nephrolithiasis for the Internist...
Nephrolithiasis for the Internist
Rajiv Kumar
Divisions of Nephrology and Endocrinology
Departments of Medicine, Biochemistry and Molecular Biology
Mayo Clinic, Rochester
Meira and Shaul G. Massry Visiting Professorship
Dr. Massry has had an exceptionally distinguished career. He has received honorary doctorates from
universities across Europe and has been the recipient
of numerous awards from universities and societies
throughout the world. Dr. Massry was the Editor-in-
Chief of the American Journal of Nephrology, and
of Mineral and Electrolyte Metabolism. He is the co-
Editor of the Textbook of Nephrology.
Dr. Massry is a past President of the National Kidney
Foundation, American Society of Renal Biochemistry
and Metabolism, International Society of Nutrition and
Metabolism in Renal Diseases, International Society of
Uremia Research and Toxicity, and International
Association of the History of Nephrology. Dr. Massry
has been a frequent guest speaker at national and
international meetings and a visiting professor at many
universities across the globe. He has published over
600 scientific papers, 111 chapters in books and edited
32 books.
Shaul G. Massry, M.D. , Professor
Emeritus of Medicine and Physiology
& Biophysics at the Keck School of
Medicine, University of Southern
California and Emeritus Chief of the
Division of Nephrology (1974-2000).
Mayo Clinic Rochester
Disclosures
• None
Objectives
• Familiarize you with recent trends in kidney
stone prevalence
• Discuss the pathogenesis of kidney stones
• Review diagnostic tests required to assess
kidney stones
• Review medical therapeutic interventions
which will reduce stone recurrence
Case 1
• You are asked to evaluate an 85 yo female with a history of Crohn's disease with multiple ileal resections and an ileal transverse colostomy. 122 cm of the ileum have been resected. At the present time the patient does not have any diarrhea, but she has had frequent loose stools in the past.
• She was evaluated in the ED for left-sided ureteric colic three weeks ago. She underwent a cystoscopy, left retrograde pyelogram, left flexible ureteroscopy, laser lithotripsy and basket extraction of stones from her left ureter. A ureteral stent was placed. Since then, she has been asymptomatic. Chemical analysis of her stones has been performed.
• The patient does take vitamin D and calcium for treatment of osteoporosis, but she has not been hypercalcemic or hypercalciuric per report. There is also a history of vitamin C use. Oral fluid intake is low.
Case 1
• VITAL SIGNS. Height 15.0 cm; weight 58.0 kg; BMI 24.2 kg/m2; temp 36.8 C; BP 99/55 mmHg; P 56 bpm, regular.
• PHYSICAL EXAMINATION. Negative except for colostomy and multiple abdominal surgical scars.
Case 1 contd.
Stone analysis is likely to reveal:
• Ca oxalate monohydrate and Ca oxalate dihydrate
• 100% uric acid
• Struvite (Ca-Mg-NH4) stone
• Brushite (Ca phosphate)
• Hydroxyapaptite
Case 1 contd.
You would recommend treatment with which of the following?
• A high fluid intake – 2.5 L/day or more
• A low oxalate diet
• Calcium carbonate 1gm po tid
• All of the above
• None of the above
Case 2
• You are asked to evaluate an 80 yo female with a history of recurrent kidney stones. Recently, she underwent a cystoscopy and laser lithotripsy for a L ureteral stone. Two and four years prior to seeing you, she had extracorporeal shock wave lithotripsy for stones in the left and right renal pelvis, respectively.
• With respect to risk factors for stones, she has a two-year history of intermittent hypercalcemia with serum Ca values as high as 11.1 mg/dL and a non-suppressed PTH. She also has a history of gout dating back twenty years, for which she takes colchicine when she has an acute attack, and for which she is on chronic allopurinol. She has not had any recent gouty attacks. With respect to medications, she takes no vitamin D, calcium, or vitamin C. She has taken prednisone in the past for a short period of time.
Case 2
• There is no history of ulcerative colitis, regional ileitis, malabsorption, or diarrhea.
• Her diet does not reveal a high oxalate or purine precursor intake. She is on treatment at the present time with Urocit-K 20 mEq PO t.i.d. as well as allopurinol.
Case 2 contd.
• VITAL SIGNS: Height: 167.3 cm. Weight: 97.60 kg. BSA(G): 2.16 M2. BMI: 34.870 KG/M2. Temperature: 36.8 °C. Blood Pressure: 141/68 mmHg. Pulse Rate: 78/minute, regular. PHYSICAL EXAMINATION: There was a left parotid mass approximately 3 cm in diameter. No nodes were felt. No other neck masses noted. The rest of the exam was normal. Labs:
PTH 120
Case 2 contd.
Case 2 contd.
Chest x-ray; 2 views: Prominent fat pad right
cardiophrenic angle. Slight scarring or atelectasis in
the right middle lobe. Calcified granuloma left lower
lobe. Mild thoracolumbar curve.
ECG normal.
Case 2 contd. ACE – 71 U/L (nl 8-53); PTH-RP < 0.2 pmol/L (nl - < 2.0 pmol/L); whole
molecule PTH – 120 pg/mL (nl 5-65 pg/mL); serum monoclonal protein
by immunofixation small IgG l.
Parathyroid scan performed with technetium 99m sestamibi and
I-123 including SPECT imaging. Subtraction imaging showed a
discordant area of increased sestimibi uptake test posterior to the
inferior pole of the right thyroid lobe consistent with an abnormal
parathyroid gland. In addition there was increased sestamibi localization
posterior to the left inferior lobe of the thyroid that is less certain but
worrisome for a second abnormal parathyroid gland. No additional foci
of discordant sestimibi uptake.
Ultrasound of the neck demonstrated a 6 mm by 8mm x 9 mm hypoechoic
nodule posterior to the lower right thyroid lobe which could be a
parathyroid adenoma. There was also a 6 mm x 7 mm hypoechoic nodule in
the posterior portion of the inferior left thyroid lobe which is
likely a benign thyroid nodule. Small area of calcification in the mid
left thyroid lobe which was not associated with a focal nodule. No
cervical adenopathy.
Case 2 contd.
• An endocrine surgeon performed a two gland parathyroidectomy with resolution of hypercalcemia and subsequent stone activity.
Intra-operative Neck Vein PTH, pg/mL
Baseline
PTH
10 minutes 15 minutes
254 48 40
Post-op Ca 9.0 mg/dL.
Pathology of parathyroid glands: A. Parathyroid, left
superior, parathyroidectomy: Normocellular parathyroid
gland (50.0 milligrams). B. Parathyroid, left inferior,
biopsy: Normocellular parathyroid tissue. C. Parathyroid,
right superior, parathyroidectomy: Hypercellular
parathyroid (230.0 milligrams). D. Parathyroid, right
inferior, parathyroidectomy: Hypercellular parathyroid
(240.0 milligrams).
Case 2 contd.
Stone analysis is likely to reveal:
• Ca oxalate monohydrate and Ca oxalate dihydrate
• 100% uric acid
• Struvite (Ca-Mg-NH4) stone
• Brushite (Ca phosphate)
• Hydroxyapaptite
Nephrolithiasis is Common, Costly and Preventable
• Nephrolithiasis is a common disorder (yearly incidence of nephrolithiasis in the US is ~ 0.5%) that is associated with considerable morbidity and economic cost.
• In the USA the economic cost is estimated at between $2.1 and $5.3 billion billion per year, with the vast majority ($4.5 billion) attributed to direct medical/urological costs.
• Strategies to accurately diagnose the type of stones and institute measures to prevent stone recurrence will have a great impact on reducing costs associated with this illness.
The Prevalence of Nephrolithiasis has Increased
• The prevalence of nephrolithiasis in the United States and Europe has increased in the two decades between 1970-1990 from about 3% to about 5%.
Percent Prevalence of History of
Kidney Stones 1976-1980 and 1988-1994
Statmatelou, Kidney International 63: 2003
Incidence of Kidney Stones
1950-1974 and 1970-2000 in Rochester, MN
Lieske et al, Kidney International (2006) 69, 760–764.
• Better diagnostic tools
• Life style
• Dietary habits
• Obesity
Why the “Stone Boom”?
Life Style Risk Factors for Stone Formation
• Low water intake : low volume and infrequent intake increased urine supersaturation
• Consumption of food rich in calories and salt, and low in fiber and alkali hypercalciuria, deficiency in urinary stone inhibitors
• Sedentary lifestyle obesity
Stone Episodes and Obesity
Siener R, Obesity Res, 12: 106-113, 2004
BMI and Relative Risk of Symptomatic Stones
Taylor E, JAMA, 293(4), 455-462 2005
Urine Composition with Obesity
• Decreased Urine pH
• Elevated urinary excretion of
Sodium
Calcium (men > women)
Phosphate, sulfate
Uric acid
Oxalate (women)
Siener R, Obesity Research 12:106-113, 2004
Nephrolithiasis is Associated with an Increase in the Incidence of CKD
Rule et al, Clin J Am Soc Nephrol, 6:2069-2075, 2011.
Nephrolithiasis is Associated with an Increased Incidence of Myocardial
Infarction
Rule et al, J Am Soc Nephrol. 2010 Oct;21(10):1641-4.
Composition of Kidney Stones
Percentage of stones Characteristics
Crystal type
Calcium oxalate monohydrate
40-60% Radio-opaque, well-circumscribed
Calcium oxalate dihydrate 40 to 60% Radio-opaque
Calcium phosphate, apatite, Ca10[PO4]6[OH]2
20-60% Radio-opaque
Calcium phosphate, Brushite, CaHPO4.2H2O
2-4% Radio-opaque
Uric Acid 5-10% Radiolucent
Struvite (magnesium ammonium phosphate)
5-15% Can be staghorn
Cystine 1.0-2.5% Mildly radio-opaque
Ammonium urate 0.5-1 .0%
Mixed stones
Calcium oxalate-phosphate 35-40% Radio-opaque
Mixed uric acid-calcium oxalate
5% Radio-opaque
Herring et al, J. Urol, 88:545, 1962; Mandel et al, J. Urol, 142-1513, 1989; Mandel et al, J. Urol, 142:1516,1989
Pathophysiology of Stones
A number of metabolic abnormalities are associated with the occurrence of renal calculi.
• Increased urinary concentration of solutes due to a reduction in fluid intake and urine volume.
• Metabolic abnormalities: Hypercalciuria, hypocitraturia, hyperoxaluria, hyperuricosuria, and altered urinary pH.
Individuals at Increased Risk for Stone Formation
• Hypercalciuria
• Hypocitraturia
• Hyperparathyroidism
• Hyperoxaluria
• GI diseases (Colitis, Crohn’s, malabsorption)
• Surgery for obesity
• Family History
• Gout/hyperuricosuria/Uric acid
• Infected stones
• Genetically determined
•Cystinuria
•Primary Hyperoxaluria
•RTA Type I
•2,8 Dihydroxyadenine
•Xanthine
Pathophysiology of Renal Stones Cause Pathophysiology Stone
Composition Clinical Clues
All Stones
Low urine volume (raises concentration of solutes)
Reduced intake or increased loss of water
Renal water conservation All stones Urine volume less than 1 L per day and osmolality greater than 600 mOsm/Kg
Calcium stones
Hypercalciuria (raises saturation of calcium salts)
Absorptive hypercalciuria
Increased absorption in intestine
Calcium oxalate or calcium phosphate
Urine Ca >6 mmol/liter (240 mg) per day
Renal leak Loss of Ca in via kidney Urine Ca >6 mmol/liter (240 mg) per day
HPT Increased absorption in the intestine and increased bone resorption
High PTH concentrations and high 1, 25(OH)2D concentrations.
Immobilization Increased bone resorption High U Ca
Excess sodium in diet
Sodium induced hypercalciuria
Increased urine Na
Excess protein or acid in diet
Protein induced bone loss and renal leak
Urine NH4 increased, high urine sulfate, low urine pH
Range of monogenic disorders
Bone loss, gut hyper-absorption and various combinations
Pathophysiology of Renal Stones Cause Pathophysiology Stone
Composition Clinical Clues
Calcium stones
Hypocitraturia (increases urinary ionized Ca, reduces inhibitor activity against Ca salts)
Renal tubular acidosis (distal type)
Abnormal renal defense of acid-base balance
Calcium phosphate
Urine citrate concentrations less than 1.7 mmol/day.
High urine pH
High acid load (absence of detectable acidemia)
Physiological hypocitraturia
Calcium phosphate and calcium oxalate
Urine citrate concentrations less than 1.7 mmol/day.
High urine pH
Hyperoxaluria (raises saturation of calcium oxalate)
Excess of dietary oxalate
Increased delivery of luminal oxalate
Calcium oxalate Urine oxalate greater than 0.4 mmol/day
Bowel disease (malabsorption, gastric bypass procedures)
Reduced formation of luminal/intestinal Ca-oxalate complexes
Calcium oxalate Urine oxalate greater than 0.4 mmol/day
Increased endogenous production of oxalate
Primary hyperoxaluria, type I and 2
Hyperuricosuria (Na urate precipitation causes nidation of Ca salts)
High purine intake High purine intake Raised production & excretion of sodium urate
Urinary uric acid excretion of greater than 600 mg/day
Gout, Myeloproliferative disease, enzymatic defect, uricosuric drugs, renal leak
Increased excretion of uric acid
Hyperuricosuria, serum uric acid may be decreased
Pathophysiology of Renal Stones
Cause Pathophysiology Stone Composition
Clinical Clues
Uric acid stones
Low urine pH or hyperuricosuria
High acid load, metabolic syndrome, other causes of hyperuricosuria
Urate salts are converted to uric acid which is insoluble and low urinary pH
Uric acid Low urine pH, less than 5.5
Cystine stones
Cystinuria Congenital mutations of di-basic amino acid transportersubunits
Increased urinary cystine and other of basic amino acids
Cystine Urine cystine greater than 150 μmol/mmol creatinine
Infection-related stones
Urinary tract infection
Urea-splitting organisms
Production of ammonium and bicarbonate ions from urea
Magnesium ammonium phosphate, carbonate apatite
High urinary pH, pyuria, positive cultures for organism producing urease
Kidney Stone Management
Recognize Risks
Manage risks
Monitor
Evaluation of the First Stone
First Stone Episode
Determine Metabolic Activity
Dual Energy CT
Urinalysis
Urine chemistries
Diet
Fluid
3-6 month follow-up
No growth
Monitor every 1-2 years
Metabolic activity
Treatment options
Chemical Evaluation of Stones
• Serum
•Ca, Pi
•PTH
•Vitamin D Metabolites
•Uric Acid
•Na, K, Cl, HCO3
• Urine
•pH
•Sediment
•Osmolality
•Gram’s stain
•Culture
• 24hr urinary profile
•Volume
•Calcium
•Citrate
•Oxalate
•Phosphorus
•Sodium
•Magnesium
•Urinary supersaturation
• Radiological Studies
•Dual energy CT
•CT Urogram
Renal Stone Characterization Using DECT
Uric acid calculus
Non-uric acid/
Calcium calculus
Hartman et al. Radiologic Clinics of North America 2012 vol:50 iss:2 pg:191 -205
Renal Stone Characterization Using DECT
Ca oxalate
calculus Hydroxyapaptite
calculus
Liu et al, Academic Radiology, 20, 1521–1525, 2013
General Measures for the Treatment of Renal Stones: Lifestyle changes
These interventions are applicable to all stones
• BMI 18-25 kg/m2
• Balancing excess fluid loss
• Dietary changes
• Physical activity
General Measures: Dietary Prevention of Stone Formation
These interventions are applicable to all stones
• Fluid • Total intake: 2.5-3.0 L/day
• Urine output: 2.0-2.5 L/day
• Intake balanced throughout the day
• Neutral beverages
General Measures: Dietary Prevention of Stone Formation
These interventions are applicable to all stones
• Limit animal protein: 0.8-1.0 grams/Kg/day
• Limit sugar and fat content
• Limit sodium: 4-5 grams/day Calcium: 1,000-1,200 mg/day (not with absorptive hypercalciuria)
• Limit oxalate intake
• Rich in vegetable fiber
• Rich in alkaline potassium
General Measures: Restriction of Dietary Animal Protein and Sodium
A high intake of animal proteins/purine precursors
• Increases urinary uric acid excretion
• Decreases urinary pH
• Decreases urinary citrate excretion
• Increases urinary calcium excretion
A high intake of sodium chloride
• High salt diet – increases urinary calcium excretion
Dietary Animal Proteins
and Salt:
Risks for Stone
Formation
Kok D at al. J Clin Endocrinol Metab. 71:661. 1990
A High Calcium Intake is Associated with Reduced Urinary Oxalate Excretion
Von Unruh G, et al, JASN 15(6), 1567-73, 2004
Specific Measures for the Treatment of Nephrolithiasis
Lifestyle or Dietary Modification
Pharmacological Treatment
Low urine volume Increase fluid intake to 2.5-3 liters per day
Increased Fluid Intake
Hypercalciuria Sodium moderation less than 150 mmol per 24 hours
Protein moderation
Hydrochlorothiazide or indapamide + potassium alkali (potassium citrate 5-10 mEq p.o. t.i.d.)
Hyperoxaluria Restriction of dietary oxalate
Avoidance of calcium restriction
Low-fat intake in malabsorption syndrome
Calcium supplementation in malabsorption syndrome or following bypass surgery
Pyridoxine for primary hyperoxaluria; liver kidney transplantation
Specific Measures for the Treatment of Nephrolithiasis
Lifestyle or Dietary Modification
Pharmacological Treatment
Hyperuricosuria Purine restriction Potassium citrate, other alkalinizing agents such as Bicitra
Allopurinol
Low urinary pH Protein restriction Potassium citrate
Cystinuria High fluid intake Potassium citrate, D-penicillamine, b-mercaptopropionyl glycine
Urinary Tract Infection Antibiotics
Specific Measures For Calcium Oxalate Stones
Assessment of Risk factors
• Hypercalciuria, Hyperoxaluria, Hyperuricosuria, Hypocitraturia
• Low urine volume
• Diet: Low fluids, High salt, High protein, High sugar
• Family History
• Sex
Measures Which Decrease the Risk of Recurrent Calcium Oxalate Stone Disease
• Low animal protein diet
• Low salt diet
• Increased fluids 2.5-3 L/day
• Normal Ca intake (1 g/day)
A High Calcium Intake is Associated with Reduced Urinary Oxalate Excretion
Von Unruh G, et al, JASN 15(6), 1567-73, 2004
Management of Calcium Oxalate Stones: Urinary Profiles, Risks and Interventions
• Hypercalciuria –
• Hydrochlorothiazide 25-50 mg/d
• Indapamide 1.25 mg/d
• Chlorthalidone 50 mg/d
• Potassium citrate 5-10 mEq p.o. t.i.d.
• Hypocitraturia –
• Lower dietary animal protein
• Potassium citrate 5-10 mEq p.o. t.i.d.
Management of Calcium Oxalate Stones: Urinary Profiles, Risks and Interventions
• Hyperoxaluria –
• Calcium 500 mg/day with meals
• Magnesium 200 - 400 mg/day
• Hyperuricosuria –
• Potassium citrate 5-10 mEq p.o. t.i.d.
• Allopurinol 100 mg/day
• Hypomagnesiuria –
• Magnesium 200 - 400 mg/day
Nephrolithiasis and Hyperoxaluria are Complications of Bariatric Surgery
• Although there is a decrease in overall mortality and
an improvement in lipid and carbohydrate
metabolism in patients after RYGB surgery, the
incidence of nephrolithiasis and hyperoxaluria
increases post-RYGB surgery.
• In a recent study of 4,639 RYGB patients who had
undergone bariatric surgery and 4,639 obese control
patients, Matlaga et al noted that 7.65% (355 of
4,639) of RYGB patients developed urolithiasis
compared to 4.63% (215 of 4,639) of the obese
control patients in the control group (Matlaga et al J. Urol, 2009).
Kidney Stones Associated with Malabsorption and Gastric Bypass Surgery:
Hyperoxaluric Stone Disease
• Increased oxalate absorption from the colon
• Excess free fatty acids – fat malabsorption
• Bind calcium and magnesium
• Leave free oxalate to be absorbed
• Fatty acids and bile salts increase colonic oxalate absorption
Kidney Stones Associated with Malabsorption and Gastric Bypass Surgery:
Hyperoxaluric Stone Disease
• Increase in Urinary supersaturation
• Decreased water absorption – low urine volumes
• Decreased absorption of crystallization inhibitors:
• Magnesium, phosphate, pyrophosphate
Kidney Stones Associated with Malabsorption and Gastric Bypass Surgery:
Hyperoxaluric Stone Disease
• Urinary Profile
•Hypocalciuria
•Hypomagnesiuria
•Hypocitraturia
•Hyperoxaluria
•Low urine volumes
•Acidic urine
• Treatment
•Correct underlying malabsorption
•Dietary calcium
•Magnesium sup.
•Citrate
•Low oxalate diet
•Increase fluids
•Decrease dietary fat
•Cholestyramine
Kidney Stones Associated with Bowel Disease: Uric Acid Stones
• Etiology: low urine output and acidic urine
• Colectomy with ileostomy – loss of fluid and alkali
• Treatment
• Alkalinize the urine
• Fluids
• Allopurinol
Stones Associated with an Acidic Urine: Uric Acid Stones
• 5-10% of all stones
• With gout, 25% form uric acid stones
• Etiology:
• Low urine volume
• Acidic urine
• Chronic diarrhea – colectomy and ileostomy
• Excess protein intake
Stones Associated with an Acidic Urine: Uric Acid Stones
• Treatment: dissolve and prevent
• Increase fluid intake and decrease protein intake
• Alkalinize the urine – citrate
• Allopurinol
Stones with an Acidic Urine: Cystine Stones
• 1% of Kidney stones formers
• Autosomal recessive : homozygotes – stones
• Defect in intestinal and renal absorption of cystine, ornithine, lysine, and arginine (COLA)
• Diagnosis:
• Crystalluria on UA – hexagonal
• Cystinuria ( 400mg/day)
• Family History
Stones with an Acidic Urine Cystine Stones
• Treatment
• Alkalinize urine to > 7.0
• Chelators: tiopronin or penicillamine (+ pyridoxine)
Stones Associated with an Alkaline Urine :Calcium Phosphate Stones
• RTA type I
• Hyperparathyroidism
• Use of absorbable alkali (Tums, Rolaids, Alka- Seltzer)
• Medullary Sponge Kidney
Stones Associated with an Alkaline Urine: RTA Type I
• Hyperchloremic Hyperkalemic Metabolic Acidosis
• Nephrocalcinosis
• Urinary Profile
• Hypercalciuria
• Hypocitraturia
• Urine pH always > 5.3
Stones Associated with an Alkaline Urine: RTA Type I
• Treatment
• High fluid intake
• Correct acidosis: K citrate
Stones Associated with an Alkaline Urine: Struvite Stones
• Magnesium ammonium phosphate stones
• All are infected
Proteus, other gram-negative organisms
• 10% of all kidney stones / 50% are bilateral
• Urine Profile : pH 8.0
• Treatment:
• Preoperative antibiotics
• Surgical removal of all stone material
• Post-op bacterialcidal antibiotics for 6-12 months
Hyperparathyroidism and Kidney Stones
The association is well-recognized – “stone, bones, groans”
etc. The association first recognized in the case of Captain
Martell by Dr. Eugene F. DuBois in 1926. Captain Martell
had become disabled by demineralization of the skeleton in
association with hypercalcemia over many years. He had
several episodes of flank pain, kidney calcification and
stones. He was extensively studied at the MGH and
eventually, a parathyroid adenoma was removed from the
mediastinum at his seventh operation in 1932 with
correction of his serum calcium.
Interestingly, in 1925 in Europe, Felix Mandl, had removed a
parathyroid tumor from a patient with kidney stones and a
bony disorder, with marked clinical improvement.
Hyperparathyroidism and Nephrolithiasis
• Only 15-20% of patients with HPT develop stones.
• The reason for this might be that patients with
stones have a concomitant increase in their
1,25(OH)2D concentrations and increase in
intestinal Ca absorption.
Broadus et al , N Engl J Med 1980; 302:421-426.
Treatment of Stone with HPT
• Identify aberrant gland
• Parathroidectomy
•Oxalate is poorly absorbed from the alimentary tract.
About 10-20 percent of the oxalate excreted in the
urine is dietary in origin, the vast majority being
endogenously derived.
•About 40 percent of oxalate production appears to be
derived from glycine metabolism.
•Most oxalate precursors are metabolized via
glyoxylate and/or glycolate the oxidation of which is
the main regulatory step in the metabolism of
carbohydrates to oxalate.
Primary Hyperoxaluria
Oxalate Metabolism
Metabolism of Oxalate
Aronson PS, Kidney International 2006
•PH1 is caused by a functional deficiency of the liver-specific
peroxisomal enzyme alanine:glyoxylate aminotransferase (AGT)
•PH2 by a deficiency of the cytosolic enzyme glyoxylate
reductase (GR) and hydroxypyruvate reductase (HPR).
•One-third of PH1 patients have significant levels of AGT catalytic
activity due to a unique intracellular protein trafficking defects in
which AGT is erroneously localized to the mitochondria.
Oxalate Metabolism
C. J. Danpure
Treatment Stones and PH
• Pyridoxine
• Hepatic or hepatic/renal
transplantation
Surgical Therapy
• Obstruction
• Persistent severe hematuria
• Persistent metabolic activity despite
maximal medical therapy
Case 1
• Patient with long standing Crohn’s disease and an intact colon.
Case 1 contd.
Stone analysis is likely to reveal:
• Ca oxalate monohydrate and Ca oxalate dihydrate
• 100% uric acid
• Struvite (Ca-Mg-NH4) stone
• Brushite (Ca phosphate)
• Hydroxyapaptite
Case 1 contd.
On a 24 hour urine you would expect to see which of the following:
• Hyperoxaluria
• Hyper-uricosuria
• Hypercalciuria
• Hypo-citraturia
• All of the above
• None of the above
Case 1 contd.
You would recommend treatment with:
• A high fluid intake – 2.5 L/day or more
• A low oxalate diet
• Calcium carbonate 1gm po bid or tid
• All of the above
• None of the above
Case 2
• Patient with primary HPT
Case 2 contd.
Stone analysis is likely to reveal:
• Ca oxalate monohydrate and Ca oxalate dihydrate
• 100% uric acid
• Struvite (Ca-Mg-NH4) stone
• Brushite (Ca phosphate)
• Hydroxyapaptite
Summary
• Nephrolithiasis is increasing in frequency
• Metabolic abnormalities can and should
be identified in the urine and serum to guide
therapy
• A treatment program can be designed based
on findings
• Serial follow-up is necessary