Practice 5 structured short- and long-answer medical questions on Blood Metabolites Measurement and Plasma Proteins. Review model answers for exam revision.
Answer: ### Reference Range for Blood Glucose Blood glucose levels vary based on fasting and diet. Fasting blood sugar is measured early in the morning before any meal and is critical for diagnosing glucose metabolism disorders. ### Applications of Blood Glucose Measurement - Detection of metabolic disorders (e.g., diabetes). - Preliminary test for diabetes before confirmatory glucose oxidase testing. - Assessing insulin function: Insulin moves glucose into cells for storage as glycogen, fats, or proteins. - Counter-regulatory hormones: Glucagon, epinephrine, cortisol, thyroxine, and growth hormone act as hyperglycemic hormones by releasing stored glucose into circulation. ### Conditions Affecting Blood Glucose Levels #### Hyperglycemia (High Blood Sugar) - Causes: Diabetes mellitus, Cushing’s syndrome (excess glucocorticoids), Pituitary adenoma (excess growth hormone), and Acute stress. #### Hypoglycemia (Low Blood Sugar) - Causes: Excess insulin administration, Addison’s disease (lack of cortisol), Bacterial sepsis, Inadequate glucose intake, Excessive glucose utilization, or Inability to synthesize glucose. ### Measurement of Blood Glucose
Answer: Model answer pending
Answer: Model answer pending
Answer: Model answer pending
Answer: ## Monitoring Diabetes ### Dipstick Test Home monitoring method using a test strip impregnated with glucose oxidase, peroxidase, and a chromogen. ### Plasma Insulin Measurement Used to investigate hypoglycemia and insulinoma. Employs sandwich immunoassay techniques. ### C-Peptide Measurement Assesses endogenous insulin production. Insulin is secreted with equimolar amounts of C-peptide. It differentiates between: - Hyperglycemia due to insulinoma (high insulin, high C-peptide). - Hyperglycemia due to exogenous insulin administration (high insulin, low C-peptide). ## Glycosylated Hemoglobin (HbA1c) - HbA1c forms when glucose reacts with hemoglobin over the RBC lifespan (120 days). - Reflects average glucose concentration over the past 2-3 months. - Mechanism: Non-enzymatic reaction where glucose-6-phosphate binds to hemoglobin's β-chain via its α-amino group, forming a Schiff base followed by Amadori rearrangement. - Normal: ~5%; Poor control: 6-15%. ## Glycosylated Proteins and Fructosamine - Albumin also undergoes glycosylation to form fructosamine. - Due to albumin's shorter half-life (19 days), fructosamine is useful for monitoring glucose control over a 3-week period. # Plasma Proteins and Their Functions ### Functions of Plasma Proteins - Transport: Albumin (calcium, bilirubin, drugs), Transferrin (iron), Caeruloplasmin (copper), Pre-albumin (Vitamin A, thyroid hormones), and Lipoproteins (lipids). - Storage: Reserves for vitamins and metal ions. - Defense: Immunoglobulins (antibodies). - Blood Clotting: Fibrinogen and other clotting factors. - Osmotic Pressure: Albumin maintains oncotic pressure to regulate fluid balance. - Catalysis: Enzymes involved in metabolic reactions. ### Classes of Plasma Proteins - Enzymes - Structural Proteins (e.g., collagen, keratin) - Contractile Proteins (actin, myosin) - Antibodies (Immunoglobulins) - Transport Proteins - Peptide Hormones (e.g., insulin) ### Clinical Significance and Analysis - Total Protein Measurement: General indicator; elevated in dehydration or chronic inflammation; decreased in liver disease, malnutrition, or nephrotic syndrome. - Electrophoresis: Separates proteins into Albumin, α1-globulins (α1-antitrypsin), α2-globulins (haptoglobin), β-globulins (transferrin), and γ-globulins (antibodies). - Clinical Correlations: Liver disease (low albumin), Kidney disease (proteinuria), and Acute Phase Response (increased CRP).