Chemical Pathology Practice Examination: OmpathStudy

Question 1 A 55-year-old diabetic patient presents to the emergency department with confusion, rapid breathing, and fruity breath odor. Random blood glucose is 28 mmol/L. ( A. Define diabetic ketoacidosis (DKA). (2 marks) ( B. List FIVE biochemical investigations you would request to confirm and manage DK C. (5 marks) ( D. Explain the biochemical basis for the acid-base disturbance in DK E. (3 marks) #### ANSWER TO QUESTION 1 ( Answer: A. Define diabetic ketoacidosis (DKA). (2 marks) ( --- Question 2 A 45-year-old man presents with severe chest pain radiating to the left arm. ECG shows ST-segment elevation. ( A. Name FOUR cardiac biomarkers used in the diagnosis of acute myocardial infarction. (4 marks) ( B. Describe the time course of troponin elevation and its clinical significanc C. (4 marks) ( D. State TWO conditions other than myocardial infarction that can cause troponin elevation. (2 marks) #### ANSWER TO QUESTION 2 ( E. Four cardiac biomarkers (4 marks - 1 mark each) - Cardiac Troponin I (cTnI) - Cardiac Troponin T (cTnT) - Creatine Kinase-MB (CK-M Answer: A. Name FOUR cardiac biomarkers used in the diagnosis of acute myocardial infarction. (4 marks) ( --- Question 3 A 35-year-old woman complains of fatigue, weight gain of 10 kg over 6 months, cold intolerance, and constipation. ( A. List FOUR thyroid function tests you would request. (4 marks) ( B. Describe the expected laboratory findings in primary hypothyroidism. (3 marks) ( C. Differentiate between primary and secondary hypothyroidism based on laboratory results. (3 marks) #### ANSWER TO QUESTION 3 ( D. Four thyroid function tests (4 marks - 1 mark each) - Thyroid Stimulating Hormone (TSH) - Free Thyroxine (Free T4) - Free… E. ( Answer: A. List FOUR thyroid function tests you would request. (4 marks) ( --- Question 4 QUESTION 4 Explain the role of the kidney in maintaining acid-base balance. ( A. Describe THREE mechanisms by which the kidney regulates acid-base balanc B. (6 marks) ( C. Define metabolic acidosis and calculate the anion gap given the following values: Na+ 140 mmol/L, Cl- 100 mmol/L, HCO3- 15 mmol/L. (4 marks) #### ANSWER TO QUESTION 4 ( D. Three mechanisms of renal acid-base regulation (6 marks - 2 marks each) - Bicarbonate Reabsorption: The proximal tubule reabsorbs approximately 80-90% of filtered bicarbonate - H+ is secreted into tubular fluid, combines with HCO3- to form H2CO3, which dissociates to CO2 and H2O - CO2 diffuses back into tubular cells and is reformed into HCO3- which enters blood - Excretion of Titratable Acids (Phosphate Buffer System): H+ ions are secreted and buffered by HPO4²- forming H2PO4- - This allows excretion of H+ without excessive lowering of urine pH - Accounts for about 30-40% of acid excretion - Ammonia Buffer System: Glutamine is metabolized in renal tubular cells to produce ammonia (NH3) and bicarbonate - NH3 diffuses into tubular lumen and combines with H+ to form NH4+ (ammonium) - NH4+ is trapped in tubular fluid and excreted in urine - Most important mechanism in chronic acidosis ( E. Definition and anion gap calculation (4 marks) Definition (2 marks): Metabolic acidosis is a primary decrease in plasma bicarbonate (HCO3- <22 mmol/L) with or without compensatory decrease in pCO2, resulting in decreased blood pH (<7.35) Anion Gap Calculation (2 marks): - Formula: Anion Gap = (Na+) - (Cl- + HCO3-) - Calculation: 140 - (100 + 15) = 25 mmol/L - Normal anion gap = 8-12 mmol/L - This represents HIGH anion gap metabolic acidosis --- Answer: A. Describe THREE mechanisms by which the kidney regulates acid-base balanc --- Question 5 A 60-year-old man with chronic back pain is found to have hypercalcemia (serum calcium 3.2 mmol/L). ( A. List FOUR biochemical investigations you would perform to evaluate hypercalcemi B. (4 marks) ( C. Describe the biochemical findings that would suggest primary hyperparathyroidism. (3 marks) ( D. State THREE clinical complications of prolonged hypercalcemi E. (3 marks) #### ANSWER TO QUESTION 5 ( Answer: A. List FOUR biochemical investigations you would perform to evaluate hypercalcemi --- Question 6 A 28-year-old woman presents with jaundice. Laboratory results show: Total bilirubin 85 μmol/L (unconjugated 70 μmol/L), ALT 350 U/L, AST 320 U/L, ALP 150 U/L. ( A. Classify jaundice based on pathophysiology and give ONE example of each typ B. (6 marks) ( C. Based on the laboratory results above, what type of jaundice does this patient likely have? Justify your answer. (4 marks)… D. Classification of jaundice (6 marks - 2 marks per typ E. - Pre-hepatic (Hemolyti Answer: A. Classify jaundice based on pathophysiology and give ONE example of each typ --- Question 7 Discuss the clinical utility and interpretation of lipid profile tests. ( A. List FIVE components typically measured in a standard lipid profil B. (5 marks) ( C. Explain the classification of lipoproteins based on density and their atherogenic potential. (5 marks) #### ANSWER TO QUESTION 7 ( D. Five components of lipid