Hydrochlorothiazide MCQs With Answer

Hydrochlorothiazide MCQs With Answer — This concise, student-focused introduction covers key aspects of hydrochlorothiazide (HCTZ) relevant to B.Pharm coursework. Topics include mechanism of action, pharmacokinetics, therapeutic uses in hypertension and edema, electrolyte disturbances (hypokalemia, hyponatremia, hyperuricemia), drug interactions, contraindications, dosing and monitoring. Emphasis on clinical implications, adverse effects, and laboratory changes helps deepen understanding for exams and practice. Relevant keywords: Hydrochlorothiazide, HCTZ, thiazide diuretic, distal convoluted tubule, Na-Cl cotransporter, hypokalemia, hyperuricemia, pharmacology, B.Pharm. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which class of diuretics does hydrochlorothiazide belong to?

• Loop diuretic
• Potassium-sparing diuretic
• Thiazide diuretic
• Osmotic diuretic

Correct Answer: Thiazide diuretic

Q2. What is the primary renal site of action of hydrochlorothiazide?

• Proximal convoluted tubule
• Loop of Henle
• Distal convoluted tubule
• Collecting duct

Correct Answer: Distal convoluted tubule

Q3. Hydrochlorothiazide lowers blood pressure mainly by inhibiting which transporter?

• Na-K-2Cl cotransporter
• Na-Cl cotransporter
• ENaC sodium channel
• Na-H exchanger

Correct Answer: Na-Cl cotransporter

Q4. Which effect on calcium handling is caused by hydrochlorothiazide?

• Increases urinary calcium excretion
• No effect on calcium excretion
• Decreases urinary calcium excretion
• Chelates calcium in plasma

Correct Answer: Decreases urinary calcium excretion

Q5. Which of the following is a primary clinical indication for hydrochlorothiazide?

• Acute pulmonary edema requiring loop diuretics
• Chronic hypertension management
• Diabetic ketoacidosis
• Severe hyperkalemia

Correct Answer: Chronic hypertension management

Q6. Typical onset of antihypertensive action after an oral dose of hydrochlorothiazide is approximately:

• 15–30 minutes
• 2 hours
• 24–48 hours
• 5–7 days

Correct Answer: 2 hours

Q7. The most common electrolyte disturbance caused by hydrochlorothiazide is:

• Hyperkalemia
• Hypokalemia
• Hypermagnesemia
• Hypernatremia

Correct Answer: Hypokalemia

Q8. Hydrochlorothiazide can exacerbate which metabolic condition by increasing serum levels?

• Hypouricemia
• Hypoglycemia
• Hyperuricemia
• Hypocholesterolemia

Correct Answer: Hyperuricemia

Q9. Hydrochlorothiazide is contraindicated in which clinical situation?

• Patients with controlled essential hypertension
• Anuria or severe renal failure without diuretic responsiveness
• Postmenopausal osteoporosis prevention

Correct Answer: Anuria or severe renal failure without diuretic responsiveness

Q10. Co-administration of hydrochlorothiazide with which drug can increase the risk of lithium toxicity?

• ACE inhibitors
• Propranolol
• Loop diuretics
• Thiazide diuretics increase lithium levels

Correct Answer: Thiazide diuretics increase lithium levels

Q11. Combining hydrochlorothiazide with which agent helps prevent hypokalemia?

• Spironolactone
• Furosemide
• Metolazone
• Amiloride antagonist

Correct Answer: Spironolactone

Q12. Which adverse effect related to glucose metabolism may occur with hydrochlorothiazide?

• Marked hypoglycemia
• New-onset diabetes or impaired glucose tolerance
• Insulin hypersensitivity
• No effect on glucose

Correct Answer: New-onset diabetes or impaired glucose tolerance

Q13. How is hydrochlorothiazide primarily eliminated from the body?

• Hepatic metabolism to active metabolites
• Renal excretion largely unchanged
• Excretion via bile into feces
• Metabolism by plasma esterases

Correct Answer: Renal excretion largely unchanged

Q14. Hydrochlorothiazide contains which chemical functional group relevant to allergy concerns?

• Carboxylic acid
• Sulfonamide
• Phenol
• Amide

Correct Answer: Sulfonamide

Q15. A common initial daily dose range of hydrochlorothiazide for hypertension in adults is:

• 500–1000 mg
• 50–100 mg
• 12.5–25 mg
• 0.5–1 mg

Correct Answer: 12.5–25 mg

Q16. Hydrochlorothiazide can be beneficial in preventing which type of kidney stones?

• Uric acid stones
• Cystine stones
• Calcium oxalate stones
• Struvite stones

Correct Answer: Calcium oxalate stones

Q17. Which mechanism contributes to metabolic alkalosis with thiazide diuretics?

• Direct inhibition of carbonic anhydrase
• Enhanced H+ secretion due to volume contraction and increased aldosterone
• Blocking bicarbonate reabsorption in PCT
• Inhibition of renal glutamine metabolism

Correct Answer: Enhanced H+ secretion due to volume contraction and increased aldosterone

Q18. Why should hydrochlorothiazide be used with caution during pregnancy?

• It causes teratogenic limb defects
• Risk of fetal electrolyte disturbances and reduced placental perfusion
• It crosses placenta and accumulates in fetal bone only
• It causes severe maternal hypoglycemia

Correct Answer: Risk of fetal electrolyte disturbances and reduced placental perfusion

Q19. Compared to hydrochlorothiazide, which thiazide-like agent has a longer half-life and more prolonged antihypertensive effect?

• Metolazone
• Chlorthalidone
• Indapamide
• Ethacrynic acid

Correct Answer: Chlorthalidone

Q20. At the cellular level in the distal convoluted tubule, hydrochlorothiazide increases calcium reabsorption primarily by:

• Blocking apical calcium channels
• Enhancing expression/activity of basolateral Na/Ca exchanger and TRPV5-mediated uptake
• Inhibiting paracellular calcium transport
• Stimulating PTH release directly

Correct Answer: Enhancing expression/activity of basolateral Na/Ca exchanger and TRPV5-mediated uptake

Q21. Which serum electrolyte is typically increased (or relatively retained) with hydrochlorothiazide therapy?

• Potassium
• Magnesium
• Calcium
• Sodium

Correct Answer: Calcium

Q22. Which laboratory tests should be monitored routinely in a patient starting hydrochlorothiazide?

• Liver function tests only
• Serum electrolytes and renal function (BUN/creatinine)
• Coagulation profile
• Serum amylase and lipase

Correct Answer: Serum electrolytes and renal function (BUN/creatinine)

Q23. Management of hydrochlorothiazide overdose principally involves:

• Immediate hemodialysis as first-line
• Supportive care with fluid and electrolyte replacement
• Administration of insulin and glucose
• High-dose corticosteroids

Correct Answer: Supportive care with fluid and electrolyte replacement

Q24. True regarding sulfonamide cross-reactivity with hydrochlorothiazide:

• There is no sulfonamide group, so no risk
• Cross-reactivity is common and hydrochlorothiazide is absolutely contraindicated
• Caution is advised because hydrochlorothiazide contains a sulfonamide moiety; allergic reactions are possible
• Sulfonamide antibiotics prevent thiazide action

Correct Answer: Caution is advised because hydrochlorothiazide contains a sulfonamide moiety; allergic reactions are possible

Q25. Chronic hydrochlorothiazide therapy may have which effect on lipid profile?

• Marked decrease in LDL and triglycerides
• No effect on lipids
• Modest increase in LDL cholesterol and triglycerides
• Profound increase in HDL only

Correct Answer: Modest increase in LDL cholesterol and triglycerides

Q26. In heart failure, hydrochlorothiazide helps by primarily:

• Increasing afterload
• Reducing preload via diuresis
• Direct inotropic stimulation
• Blocking beta-adrenergic receptors

Correct Answer: Reducing preload via diuresis

Q27. Urinary calcium excretion after hydrochlorothiazide administration is typically:

• Increased markedly
• Unaffected
• Decreased
• Converted to insoluble salts

Correct Answer: Decreased

Q28. Thiazide diuretics like hydrochlorothiazide are generally ineffective when glomerular filtration rate is:

• Greater than 90 mL/min/1.73 m2
• Between 60–90 mL/min/1.73 m2
• Less than approximately 30 mL/min/1.73 m2
• Exactly 50 mL/min/1.73 m2

Correct Answer: Less than approximately 30 mL/min/1.73 m2

Q29. The elimination half-life of hydrochlorothiazide is approximately:

• 30–60 minutes
• 6–15 hours
• 3–5 days
• Less than 5 minutes

Correct Answer: 6–15 hours

Q30. The mechanism by which hydrochlorothiazide can precipitate gout is:

• Increased uric acid production in the liver
• Decreased renal excretion of uric acid leading to hyperuricemia
• Promotion of uric acid crystallization by lowering pH of urine only
• Direct release of urate from joints

Correct Answer: Decreased renal excretion of uric acid leading to hyperuricemia

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