8. Carbohydrates Flashcards
Which ketone body is not measured using routine urinalysis reagent strips?
Beta-hydroxybutyric acid (BHB)
What is glycolysis
Conversion of glucose to pyruvate/lactate
What reagent is used to detect ketones?
Sodium nitroprusside
What is gluconeogenesis
Production of glucose from non-carbohydrate sources (glycerol, FAs, AAs)
What is acetest
Semi-quantitative test that determines ketones in urine and serum
What happens to lyte levels during diabetic ketoacidosis?
Na+ and K+ are usually decreased due to polyuria and excretion of salts of the acids produced by the utilization of lipids for energy
Why should grey top tubes be cautiously used for other tests?
Enzymes inhibited by additives in it
Equation for calculated osmolality?
2*(Na+) + BUN + glucose
What is glycogenesis
Formation of glycogen from glucose
What does acetest detect? Doesn’t detect?
Detects: acetoacetate, lesser extent acetone
Does NOT detect BHB
Clinical significance of elevated HgbA1C?
Indicates poor glucose control over the past 6-12 weeks
Values >= 7 mmol/L = poor diabetic control
Therapeutic goal is <6.5%
What would cause an elevated anion gap in a ketoacidosis patient?
Increased ketones (unmeasured anion)
Source of cortisol?
Adrenal cortex
What is glycogenolysis
Breakdown of glycogen to G6P to enter glycolysis cycle
Production of glucose from glycogen
2 enzymatic methods for glucose determination
- Glucose oxidase
- Hexokinase
Equation for osmolar gap?
Osmolar gap = measured osmol - calculated osmol
What are the most common causes of hypoglycemia?
- inappropriate insulin production
- insulin injection
- ingestion of oral hypoglycemic agents
Source of epinephrine?
Adrenal medulla
4 diagnostic tests to determine enzyme deficiencies in carb malabsorption?
- BC New Born Screening Program
- Confirmatory tests
- Tolerance testing
- Genetic testing
What is microalbuminuria?
Excretion of urinary albumin at a rate of 20-200 ug/min or 20-300 mg/24 hr
Highly predictive of diabetic nephropathy in type 1 diabetes
5 hormones that affect [glucose] and their effect on it
- Insulin - lowers
- Glucagon - increase
- Cortisol - increase
- Epinephrine - increase
- Growth hormone - increase
2 additives in grey top tubes and their functions
Potassium oxalate - anticoagulant
Sodium fluoride - glycolytic inhibitor
How do glucose levels differ in venous and capillary specimens? How do they differ if the patient is fasting?
Fasting: all 3 (arterial, capillary, venous) comparable
After meal: venous levels lower than capillary/arterial (common estimate = 10%)
When are ketones present in the blood?
When there is impaired carb metabolism w/ breakdown of FA:
- uncontrolled diabetes mellitus
- starvation
- vomiting
- low carb diet
Renal threshold?
10 mmol/L
Hormone that has the greatest effect on increase glucose levels
Glucagon
What is glycated hemoglobin?
Hemoglobin A w/ glucose attached to the beta chains (hemoglobin A1)
3 major ketone bodies?
- Acetone
- Acetoacetic acid
- Beta-hydroxybutyric acid (BHB)
Source of growth hormone?
Anterior pituitary
Define renal threshold
Blood concentration of a substance that can be reabsorbed by the renal tubules
Once blood level > threshold: glucose excreted in urine
How is gestational diabetes diagnosed?
Screening test = O’Sullivan test
Woman given 50g load og glucose
1 hr plasma glucose >= 7.9 mmol/L = abnormal; risk of fetal death/neonatal complications
Most common method for glycated hemoglobin?
Affinity chromatography
Glycate Hgb binds to column; non-glycated Hgb do not
What specimen is required for glycated hemoglobin?
Whole blood
Fasting not required
