Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO.
Carbohydrates CHO
description
Transcript of Carbohydrates CHO
![Page 1: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/1.jpg)
Carbohydrates (CHO)
JEANNIE LIMAYO, RMT MPH DTA
BCM 314
![Page 2: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/2.jpg)
Carbohydrates
• Are hydrates of aldehyde or ketone derivatives based on the location of the CO functional grp.
• Monosaccharide, disaccharides, oligosaccharides, polysaccharides- CHOs.
• Glycol aldehyde-is the simpliest CHO• Glucose, maltose, fructose, lactose and
galactose- reducing substances/sugars.
![Page 3: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/3.jpg)
• The presence of a double bond and a negative charge in the enol anion makes glucose an active reducing substance.
• Sucrose- most common non-reducing sugar• Non-reducing sugar do not contain an active
ketone or aldehyde group.• Glucose is the only CHO to be directly used for
energy or stored as glycogen.
![Page 4: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/4.jpg)
Pathways in Glucose Metabolism
• Glycolysis – metabolism of glucose molecule to pyruvate or lactate for production of energy
![Page 5: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/5.jpg)
Pathways in Glucose Metabolism
• Gluconeogenesis- formation of glucose 6-phosphate from noncarboydrate sources
![Page 6: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/6.jpg)
Pathways in Glucose Metabolism
• Glycogenolysis – breakdown of glycogen to glucose for use of energy
![Page 7: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/7.jpg)
Pathways in Glucose Metabolism
• Glycogenesis – conversion of glucose to glycogen for storage
![Page 8: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/8.jpg)
Pathways in Glucose Metabolism
• Lipogenesis – conversion of carbohydrates to fatty acids
![Page 9: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/9.jpg)
Pathways in Glucose Metabolism
• Lipolysis – decomposition of fat
![Page 10: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/10.jpg)
Carbohydrates Classification
• CLASSIFICATION is based on 4 different properties– Size of the base carbon chain– Location of the CO function group– Number of sugar units– Stereochemistry of the compound
![Page 11: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/11.jpg)
CLASSIFICATIONS OF CARBOHYDRATES:
• Based on the number of carbons in the molecule (Generic classifications)– 3 carbons compound (Trioses) e.g. glyceraldehyde– 4 carbons compound (Tetroses)– 5 carbons compound (Pentoses)* (Note: *most
important)– 6 carbons compound (Hexoses)*
![Page 12: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/12.jpg)
CLASSIFICATIONS OF CARBOHYDRATES:
• Based on the location of CO functional group– Hydrates of aldehyde or ketone– Aldose – functional group: aldehyde – Ketose – functional group: ketone
• anomeric carbon – carbon in the functional group
![Page 13: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/13.jpg)
MODELS TO REPRESENT CARBOHYDRATES
• FISHER PROJECTION– Has the aldehyde or ketone at the top of the
drawing– Carbons are numbered starting at the aldehyde or
ketone end– Straight chain or cyclic (linked in hemiacetal form)
![Page 14: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/14.jpg)
MODELS TO REPRESENT CARBOHYDRATES
• HAWORTH PROJECTION– Cyclic form– More representative of the actual structure– Formed when the functional group (ketone or
aldehyde) reacts with an alcohol group on the same sugar to form a ring (hemiacetal ring)
![Page 15: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/15.jpg)
Pancreas
• Functions: an endocrine and exocrine organ in the control of the CHO metabolism
• As an exocrine gland, it produces and secretes an amylase responsible for the breakdown of ingested complex CHO.
• As an endocrine gland, it secrets the hormones; insulin, glucagon and somatostatin from different cells residing in the islets of langerhans in the pancreas.
![Page 16: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/16.jpg)
INSULIN• The primary hormone responsible for the entry of
glucose into the cell.• Synthesized by the beta cells of the islets of
langerhans in the pancreas• It is normally released when glucose levels are high.• It is the only hormone that decreases glucose levels
– hyploglycemic agent • Stored from sources such as liver, fat and muscles.• Has a reciprocal relationship with glucagon.• Promotes glycogenesis, lipogenesis and glycolysis;
decreases glycogenolysis.
![Page 17: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/17.jpg)
GLUCAGON
• The primary hormone responsible for increasing glucose – hyperglycemic agent
• Synthesized by the alpha cells of the islets of langerhans in the pancreas
• It is released during stress and fasting states.• It enhances catabolic functions during fasting
periods; promotes glycogenolysis and gluconeogenesis
![Page 18: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/18.jpg)
Other hormones that tend to increase glucose concentration1. Cortisol and corticosteroids (Glucocorticoids) Secreted by the cells of the zona fasciculata and
zona reticularis of the adrenal cortex Decreases intestinal entry of glucose into the cell It promotes gluconeogenesis and lipolysis
2. Cathecolamines It is released from the chromaffin cells of the
adrenal medulla Inhibits insulin secretions and promotes
glycogenolysis and lipolysis.
![Page 19: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/19.jpg)
3. Growth hormones(Somatotrophic) Secreted by the anterior pituitary gland Decreases entry of glucose into the cell It promotes glycogenolysis and glycolysis.
4. Thyroid hormones Secreted by the thyroid gland. Promotes glycogenolysis, gluconeogenesis and
intestinal absorption of glucose.
5. Adrenocorticotropic hormones (ACTH) It stimulates release of cortisol from the adrenal
cortex It promotes glycogenolysis and gluconeogenesis.
![Page 20: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/20.jpg)
6. Somatostatin Produced by the delta cells of the islets of
langerhans of the pancreas It is primarily inhibits the action of insulin and
glucagon.
![Page 21: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/21.jpg)
Clinical conditions of carbohydrate metabolism
1. Hyperglycemia Increase in blood glucose levels Causes: stress, severe infection, dehydration or
pregnancy, pancreatectomy, hemochromatosis, insulin deficiency, abnormal insulin receptor.
FBS level= 126 mg/dL All adults older than 45 yrs.old should have a
measurement of FBS every 3 years unless the individual is diabetic.
![Page 22: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/22.jpg)
Lab. findings in Hyperlgycemia
1. Increase glucose in plasma and urine
2. Increase urine specific gravity
3. Ketones in serum and urine
4. Decrease blood and urine pH(acidosis)
5. Electrolyte imbalance
![Page 23: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/23.jpg)
2. Hypoglycemia Involves decreased glucose levels and can have
many causes. Warning signs and symptoms of hypoglycemia are all
related to CNS. 80 mg/dl to 5mg/dl (2.8-3.0 mmol/L) – observable
symptoms of hypoglycemia occur.
CLASSIFICATION:
1. Drug administration- insulin alcohol, salicylates, sulfonamides, pentamidine. Etc.
2. Critical illnesses- hepatic failure, sepsis, renal failure, cardiac failure, malnutrition
3. Hormonal deficiency- epinephrine, glucagons, cortisol, growth hormone
![Page 24: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/24.jpg)
4. Endogenous hyperinsulinism- pancreatic beta cell disorder
5. Autoimmune hypoglycemia- insulin antibodies
6. Non beta cell tumors- leukemia, hepatoma, pheochromocytoma, lymphoma etc.
7. Hypoglycemia if infancy and childhood- galactosemia, GSD, Reye’s syndrome
8. Alimentary (reactive) hypoglycemia- post-gastric surgery
9. Idiopathic (functional) postprandial hypoglycemia
A diagnosis of hypoglycemia should not be mad unless a patients meets the criteria WHIPPLE’S TRIAD – low blood glucose concentration with typical symptoms alleviated by glucose administration.
![Page 25: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/25.jpg)
Diabetes Mellitus(DM)
• A group of metabolic disorders characterized by hyperglycemia resulting from defects in insulin secretion, insulin or both.
• Fasting plasma glucose concentrations > 26 mg/dL on more than one testing are diagnostic DM.
• Glucosuria occurs when the plasma glucose levels exceeds 180 mg/dL (9.99mmol/L) with normal renal function
• In severe DM, the ratio of beta-hydroxybutyrate to acetoacetate is 6:1
![Page 26: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/26.jpg)
Classification of DM:
A. Type 1 DM
Formerly known as:
Insulin Dependent Diabetes Mellitus (IDDM)
Juvenile Onset Diabetes Mellitus
Brittle Diabetes
Ketosis-Prone Diabetes• Is a result of cellular-mediated autoimmune destruction of the
beta cells of the pancreas.• Diabetic individuals have insulinopenia (absolute insulin
deficiency) because of loss of pancreatic beta-cells and depend on insulin to sustain life and prevent ketosis.
• 80-90% reduction in the vol. of the beta cell is required to induce symptomatic type 1 DM
![Page 27: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/27.jpg)
• Signs and symptoms: polyuria, polydipsia, polyphagia, rapid wt. loss, hyperventilation, mental confusion and possible loss of consciousness.
• Complications: nephropathy, neuropathy, and retinopathy – microvascular disorders.
• Microalbumin of 50-200 mg/24hrs. – diabetic nephropathy
• Urine albumin excretion rate of 200 g/minute – overt diabetic nephropathy.
Idiopathic Type 1 DM is a form of type DM that has no known etiology, is strongly inherited, does not have beta-cell auto antibodies and have episodic requirements for insulin replacement.
![Page 28: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/28.jpg)
• Type 2 DM
Formerly known as: Non-insulin Dependent Diabetes Mellitus
Adult Type/maturity Onset Diabetes Mellitus
Stable Diabetes
Ketosis- Resistant Diabetes
Receptor-Deficient Diabetes Mellitus• Characterized by hyperglycemia du to an individual’s
resistance to insulin; there is relative insulin deficiency.• Associated with strong genetic predisposition and not
related to an autoimmune disease.• It has been described as a geneticist’s nightmare.• Has a milder symptoms as compared to type 1, however,
untreated type 2 DM will result to nonketotic hyperosmolar coma- overproduction of glucose (>500mg/dL), sever dehydration, electrolyte imbalance, and increased BUN and creatinine.
![Page 29: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/29.jpg)
Risk factors
• Risk factors: obesity, family history, advanced age,
hypertension, lack of exercise, impaired glucose metabolism.
![Page 30: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/30.jpg)
![Page 31: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/31.jpg)
C. Other specific types of diabetes
1. Pancreatic disroders
2. Endocrine disorders –Cushing’s syndrome, pheochromocytoma, accromegaly and thyrotxicosis
3. Drugs or chemical inducers of beta cells dysfunction (dilantin and pentamidine)and impair insulin action (thiazides,glucocorticoids)
4. Genetic syndromes- down syndrome, klinefelter’s syndrome, leprechaunism etc.
D. Gestational DM(GDM)\• Characterized by impaired ability to metabolized CHO
usually caused by a deficiency of insulin,metabolic or abnormal changes occuring in pregnancy and disappearing after delivery but in some cases returning yrs. later
![Page 32: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/32.jpg)
• Glucose intolerance with onset or first recognition during pregnancy
• Screening should be performed between 24 and 23 wks. Of gestation
• A plasma glucose concentration of 140 mg/dL or greater requires a full diagnostic glucose tolerance test (3hr GTT with 100g glucose)
GDM results:
FBS = >105 mg/dL
1 hr. = < 190 mg/dL
2 hrs. = 165 mg/dL
3 hrs. = 145 mg/dL
![Page 33: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/33.jpg)
• GDM is diagnosed when any two of the above mentioned four values are met or exceeded.
• After giving birth, woman with GDM should be evaluated 6-12 wks. Postpartum
• Infants born to diabetic mothers are at increased risk for respiratory distress syndrome, hypocalcemia and hyperbilirubinemia.
4. Impaired Fasting Glucose• Characterized by fasting blood glucose
concentrations between normal and diabetic values.
![Page 34: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/34.jpg)
5. Impaired Glucose tolerance• Characterized by fasting blood glucose
concentration less than those required for the diagnosis of DM, but the OGTT is between normal and diabetic values.
![Page 35: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/35.jpg)
Diabetes Insipidus Deficiency of anti diuretic hormone released by
the posterior gland.
Clinical picture include:
1. Normoglycemia
2. Polyuria with low specific gravity
3. Polydipsia
4. Polyphagia - ocassional
![Page 36: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/36.jpg)
Glucose Methodologies
• Fasting glucose in whole blood is 15% lower than in serum or plasma.
• Serum or plasma must be separated from the cells within one hour to prevent losses of glucose.
• At rm. Temp. (20-25C), glycolysis decreases glucose by 5-7%/hour (5-10mg/dL) in normal uncentrifuged coagulated blood.
• At refrigerated temp. (4 C) glucose is metabolized at the rate of about 1-2 mg/dL/hr.
![Page 37: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/37.jpg)
• WBC and RBC metabolize glucose resulting to decrease value in clotted, uncentrifuge blood.
• CSF glucose concentration should be approximately 60% (40-60 mg/dL) of the plasma concentrations.
• Plasma glucose levels increase with age – fasting 2 mg/dL/decade; postprandial, 4mg/dL/decade; glucose challenge, 8-13 mg/dL/decade.
![Page 38: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/38.jpg)
I. CHEMICAL METHODS
A. Oxidation Reduction Methods
1. Alkaline Copper Reduction Methods Reduction of cupric ions to cuprous oxide in
hot alkaline solution by glucose.
a. Folin Wu Method
b. Nelson Somogyi Method
c. Neocuproine method
d. Benedict’s method- used for detection and quantitation of reducing substances in body fluids like blood and urine.
e. Citrate or tartrate as stabilizing agent
![Page 39: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/39.jpg)
2. Alkaline Ferric Reduction Method (Hagedorn Jensen)
• Reduction of a yellow ferricyanide to a colorless ferrocyanide by glucose (inverse colorimetry)
3. Condensation Method
II. Enzymatic Method Acts on glucose but not on other sugars and not
on other reducing substances.
1. Glucose oxidase method
> Measures the beta-D glucose
![Page 40: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/40.jpg)
a. Colorimetric Glucose Oxidase Method (saifer Gernstenfield Method)
b. Polarographic Glucose oxidase The enzymatic conversion of glucose is
quantitated by the consumption of oxygen Measure rate of oxygen consumption.
2. Hexokinase Method• Most specific glucose method ; reference
method
![Page 41: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/41.jpg)
NOTES TO REMEMBER Ǚ
• Elevated amounts of bilirubin, uric acid and ascorbate – false decreased values of glucose(glucose oxidase method)
• Hemolysis affects hexokinase method – false low glucose value
• The enzymatic conversion of glucose to product is quantitated by a color change reaction at the last of a series of coupled chemical reactions (kinetic analysis)
![Page 42: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/42.jpg)
3. Dextrostics• Important in establishing correct insulin amount
for next dose• Effective in reducing the rate of development of
diabetic complications
![Page 43: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/43.jpg)
Samples for Glucose Measurement
1. RBS – random Blood Sugar
- requested during insulin shock, hyperglycemic ketonic coma
2. FBS – Fasting Blood Sugar
- NPO (Non-Per Orem) 6-8hrs.
3. 2-HR PPBS – 2 hour Post Prandial Blood Sugar
- below 110 mg/dL at 2 hours
4. GTT – Glucose Tolerance Test
![Page 44: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/44.jpg)
Requirements:
CHO depletion and inactivity or bed rest impair glucose tolerance
GTT is unnecessary to do for women under 25 yrs. Old who have normal body wt. no family history of diabetes and are not member of an ethnic group with high prevalence of diabetes.
1. Patient should be ambulatory
- CHO depletion and inactivity or bed rest impair glucose tolerance
2. Fasting of 8-16 hrs.
![Page 45: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/45.jpg)
3. Unrestricted diet of 150 gms. CHO/day for 3 days prior to testing.
4. The patient should not smoke and drink alcohol.
5. Glucose Load
- 75 gms (standard glucose load)
-100 gms
-1.75g of glucose/kg body wt. (children)
![Page 46: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/46.jpg)
Procedure for GTT• The patient should avoid exercise, eating and
drinking (except water) and smoking during testing
• For nonpregnant women and adults, only the fasting and the 2 hour sample may be measured or accrdg. To the physician’s request
1. Collect the fasting blood sample
2. Instruct the patient to drink the glucose load within 5 mins.
3. Collect blood sample after 30 mins., 1 hour, 2 hours, 3 hours respectively.
![Page 47: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/47.jpg)
Kinds of Glucose Tolerance Testa. Oral Glucose Tolerance Test
> Janney-Isaacson Method (single dose method)
>Exton Rose Method (divided oral dose or double method)
b. Intravenous GTT
> used for DM patients with GI disorders.
>determine glucose by getting blood samples every 10mins.for one hour
>0.5 g of glucose/kg body wt. (given within 3mins.) administered intravenously
>fasting sample is also required.
![Page 48: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/48.jpg)
Indications
a. Those who are unable to tolerate a large CHO load.
b. Those with altered gastric physiology
c. Those who had undergone previous operation or surgery in the intestine.
d. Those with chronic malabsorption syndrome.
![Page 49: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/49.jpg)
Criteria of Fasting Plasma Glucose (FPG)
1. Non-diabetic = <110mg/dl
2. Impaired PG = 110g/dl but <126mg/dl
3. DM = 126mg/dl
Categories of Oral Glucose Test
1. Normal GTT = 2hr PG <140mg/dl
2. Impaired GTT = 2hr PG 140mg/dl but < 200 mg/dl
3. DM = 2hr PG 200mg/dl
![Page 50: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/50.jpg)
Diagnostic criteria for DM
1. RBS = 200 mg/dl (w/ symptoms of DM)
2. FBS = 126 mg/dl
3. 2-hr post glucose = 200 mg/dl
![Page 51: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/51.jpg)
5. Glycosytated/glycated hemoglobin• Also called glycated hemoglobin• Largest subfraction of normal hemoglobin in both
diabetic and non-diabetic individuals.• A glucose molecule attached to one or both N-
terminus valines of the beta-polyp chains of normal adult hemoglobin
• A reliable method in the monitoring of long term glucose control
• It reflects the average blood glucose level over the previous 2-3mos.
• 3-6% of Hgb is glycosylated; 18-20% is prolonged hyperglycemia.
• For every 1% change in the HbA value, 35mg/dL is added to plasma glucose.
![Page 52: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/52.jpg)
• Older RBCs have higher HbA, iron deficiency anemia – high levels
• Not suitable for patients with shortened RBC lifespan disorders.
• Specimen for testing, EDTA whole blood• Preferred method, affinity chromatography
6. Fructosamine• Also called glycosylated or glycated
albumin/plasma protein ketoamine.• A reflection of short term glucose control (2-3wks)
![Page 53: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/53.jpg)
• May be useful for monitoring diabetes individuals w/ chronic hemolytic anemias and hemoglobin variants.
• It should not be measured in cases of low plasma albumin.
Other clinical Disorders of Carbohydrate
Metabolism
1.Galactosemia
> A congenital deficiency; one of three enzymes involved in galactose metabolism
![Page 54: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/54.jpg)
• Cause of failure to thrive syndrome in infants• 3deficient enzymes: galactose 1-phophate uridyl
transferase galactokinase and uridine diphosphate galastose 4-epimerase
• Cllinical features: jauncide, hepatomegally, easy bruisability,sepsis, cataract, hypotonia and sensory neural deafness.
• Diagnostic test: erythrocyte galactose- 1-PO4 uridyl transferase activity.
![Page 55: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/55.jpg)
2. Essential fructosuria• An autosomal recessive disorder characterized by
fructokinase deficiency• Diagnostic indicator: (+) fructose in urine
3. Hereditary fructose intolerance• A defect of fructose 1-6-b phosphate aldolase B
activity in the liver, kidney and intestine.• Inability to convert fructose-1-phosphate and
fructose-1,6-phosphate into dihyroxyacetone phosphate,glyceraldehyde-3-phosphate and glyceraldehydes.
• Clinical features: irritability, seizures, and hepatomegaly
![Page 56: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/56.jpg)
4. fructose-1,6-biphosphate deficiency• A defect in fructose-1,6-biphosphate results in
failure of hepatic glucose generation by glucoriogenic precursors such as lactate and glycerol.
• Clinical features: hypoglycemia, lactic acidosis convulsion and coma.
5. Glycogen Storage Disease (GSD)• Deficiency of a specific enzyme involved in the
metabolism of glycogen• Inherited as autosomal recessive trait
![Page 57: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/57.jpg)
• Blood specimen are collected for 2hrs at 15 mins. Interval
• Von Gierke disease – most common GS
![Page 58: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/58.jpg)
![Page 59: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/59.jpg)
Notes to Remember
1. CSF glucose• It is abt. 60-70% of the blood plasma glucose
level• Any changes in blood sugar are reflected in the
CSF approximately one hour later because of the lag in CSF equilibrium time.
• A blood glucose specimen should be collected at least 60 mins. Before the lumbar puncture.
• Increased levels: diabetes• Decreased levels: bacterial meningitis, TB,
fungal and amebic meningitis.
![Page 60: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/60.jpg)
• Reference value:40-70 mg/dL (adult)
60-80 mg/dL (child)• Normal CSF to glucose ratio: <0.5
2. C-Peptide test • Formed during the conversion of pro-insulin to
insulin.• The amount of circulating C-peptides provides
reliable indicators for pancreatic and insulin secretionS (beta cells functions)
![Page 61: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/61.jpg)
• Used to monitor individual responses to pancreatic surgery.
• To evaluate hypoglycemia• Specimen: fasting blood
Test for ketone bodies:
1. Gerhard’s ferric chloride test- reacts only w/ acetoacetate
2. Nitroprusside test- 10x more sensitive to acetoacetate than to acetone
3. Acetest tablets- detects acetoacetate and acetone
![Page 62: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/62.jpg)
4. ketosux- detects acetoacetate better than acetone
5. Ketosite assay- detects beta hydroxybutyrate; not widely used.
![Page 63: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/63.jpg)
![Page 64: Carbohydrates CHO](https://reader035.fdocuments.us/reader035/viewer/2022081421/563db916550346aa9a99e628/html5/thumbnails/64.jpg)
Thank You for Listening