Q: Which of the following equations best represents the inhibition of the Na+/Cl− cotransporter (NCC) by thiazide diuretics in the distal convoluted tubule?

$$\mathrm{Na^+ + Cl^- \xrightarrow{NCC} \text{Reabsorption}}$$

Question 1

Which of the following diuretic classes acts primarily by inhibiting the Na+/K+/2Cl− cotransporter (NKCC2) in the thick ascending limb (TAL) of Henle’s loop?

Accepted Answer

Loop diuretics

Question 2

A patient with heart failure develops hypokalemia after starting a diuretic. Which of the following mechanisms best explains the hypokalemia seen with loop diuretics?

Accepted Answer

Increased Na+ delivery to the collecting duct enhances K+ secretion

Question 3

Which diuretic is most likely to cause hypercalcemia due to enhanced Ca2+ reabsorption in the distal convoluted tubule?

Accepted Answer

Hydrochlorothiazide

Question 4

A patient with cirrhosis develops hepatic encephalopathy after starting a diuretic. Which diuretic is contraindicated due to its effect on urinary NH4+ excretion?

Accepted Answer

Carbonic anhydrase inhibitors

Question 5

Which of the following equations best represents the dehydration of carbonic acid catalyzed by carbonic anhydrase in the proximal convoluted tubule?

Accepted Answer

$$\mathrm{H_2CO_3 \rightarrow CO_2$ + H_2O}$$

Question 6

A patient with nephrolithiasis due to hypercalciuria is prescribed a diuretic to prevent calcium-containing kidney stones. Which diuretic is most appropriate?

Accepted Answer

Hydrochlorothiazide

Question 7

Which diuretic is most likely to cause ototoxicity, especially when combined with aminoglycoside antibiotics?

Accepted Answer

Furosemide

Question 8

A patient with diabetes mellitus is started on an SGLT2 inhibitor. Which of the following effects is expected from this drug?

Accepted Answer

Decreased hemoglobin A1c and mild diuretic effect

Question 9

Which of the following diuretics is NOT a sulfonamide derivative and is less likely to cause allergic reactions in patients with sulfa allergy?

Accepted Answer

Ethacrynic acid

Question 10

A patient with severe heart failure is refractory to loop diuretics. Which combination therapy is most likely to produce dramatic synergy and mobilize large amounts of fluid?

Accepted Answer

Loop diuretic plus thiazide diuretic

Question 11

Which diuretic is most likely to cause life-threatening hyperkalemia, especially in patients with renal insufficiency or those taking ACE inhibitors?

Accepted Answer

Potassium-sparing diuretics

Question 12

A patient with acute mountain sickness is treated with acetazolamide. What is the primary mechanism by which acetazolamide alleviates symptoms?

Accepted Answer

Increases bicarbonate excretion, causing mild metabolic acidosis

Question 13

Which of the following equations best represents the inhibition of the Na+/Cl− cotransporter (NCC) by thiazide diuretics in the distal convoluted tubule?

Accepted Answer

$$\mathrm{Na^+ + Cl^- \xrightarrow{NCC} 	ext{Reabsorption}}$$

Question 14

A patient with SIADH is treated with tolvaptan. Which receptor is selectively antagonized by this drug?

Accepted Answer

V2 receptor

Question 15

Which diuretic is most likely to cause hyponatremia due to hypovolemia-induced elevation of ADH, reduction in the diluting capacity of the kidney, and increased thirst?

Accepted Answer

Thiazide diuretics

Question 16

A patient with Liddle syndrome is best treated with which diuretic?

Accepted Answer

Amiloride

Question 17

Which diuretic is most likely to cause acute renal failure when combined with indomethacin?

Accepted Answer

Triamterene

Question 18

A patient is prescribed mannitol to reduce intracranial pressure. Which of the following is a major toxicity associated with mannitol use in patients with heart failure?

Accepted Answer

Extracellular volume expansion and pulmonary edema

Question 19

Which diuretic is most likely to cause gynecomastia due to its action on androgen and progesterone receptors?

Accepted Answer

Spironolactone

Question 20

A patient with hyperkalemia is treated with a loop diuretic. Which equation best represents the effect of loop diuretics on potassium excretion?

Accepted Answer

$$\mathrm{K^+_{urine} = K^+_{filtered} + K^+_{secreted} - K^+_{reabsorbed}}$$

Diuretic Agents: Mechanisms, Classes, and Clinical Applications

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