Diuretics Practice Questions

Q: Which drug commonly causes gynecomastia?

Spironolactone. **Explanation:** **Spironolactone** is a potassium-sparing diuretic and a competitive aldosterone antagonist. It is the most common pharmacological cause of gynecomastia. The underlying mechanism is twofold: 1. **Anti-androgenic effect:** It binds to and blocks androgen receptors. 2. **Hormonal imbalance:** It inhibits testosterone synthesis and increases the peripheral conversion of testosterone to estradiol. This shift in the estrogen-to-androgen ratio leads to the development of glandular breast tissue in males. **Analysis of Incorrect Options:** * **B. Rifampicin:** This is an enzyme inducer (CYP450). While it can alter the metabolism of various hormones, it is not classically associated with gynecomastia. * **C. Penicillin:** This is a beta-lactam antibiotic with no hormonal activity; it does not cause gynecomastia. * **D. Bumetanide:** This is a potent loop diuretic. Unlike spironolactone, loop diuretics do not interfere with steroid hormone receptors. **High-Yield Clinical Pearls for NEET-PG:** * **Eplerenone:** A selective aldosterone antagonist that does **not** cause gynecomastia because it has low affinity for androgen and progesterone receptors. It is the preferred alternative if a patient develops breast tenderness on spironolactone. * **Mnemonic for drugs causing Gynecomastia (DISCO):** **D**igoxin, **I**soniazid, **S**pironolactone, **C**imetidine, **O**estrogens/Ketoconazole. * **Cimetidine:** Another high-yield cause; it acts as a H2 blocker and also has significant anti-androgenic properties.

Q: Which diuretic can be used in renal failure?

Furosemide. **Explanation:** **Furosemide** is the correct answer because it is a high-ceiling loop diuretic that remains effective even when the Glomerular Filtration Rate (GFR) falls below 30 mL/min. In renal failure, the delivery of solutes to the distal nephron is reduced; loop diuretics are potent enough to inhibit the $Na^+-K^+-2Cl^-$ symporter in the thick ascending limb, maintaining diuresis and managing fluid overload in patients with chronic kidney disease (CKD). **Why the other options are incorrect:** * **Chlorothiazide & Chlorthalidone:** These are Thiazide/Thiazide-like diuretics. They generally lose their efficacy when GFR is less than 30 mL/min (except for Metolazone and Indapamide). Using them in advanced renal failure is ineffective for fluid management. * **Mannitol:** This is an osmotic diuretic. In renal failure, Mannitol is not excreted efficiently, leading to its accumulation in the extracellular fluid. This causes "osmotic shift," drawing water out of cells and potentially leading to acute pulmonary edema or congestive heart failure. It is contraindicated in established anuria. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Furosemide is the drug of choice for acute pulmonary edema and edema associated with CKD. * **Metolazone Exception:** While most thiazides fail in renal failure, Metolazone can be combined with Loop diuretics (Sequential Nephron Blockade) to treat refractory edema in CKD patients. * **Ototoxicity:** Furosemide can cause dose-dependent ototoxicity, especially when administered rapidly IV or combined with aminoglycosides. * **Electrolyte Profile:** Loop diuretics cause "Hypo-everything" (Hypokalemia, Hypomagnesemia, Hypocalcemia), except for Hyperuricemia and Hyperglycemia.

Q: Which of the following side effects is associated with Spironolactone?

Hyperkalemia. **Explanation:** **Spironolactone** is a potassium-sparing diuretic that acts as a competitive antagonist of the **Mineralocorticoid Receptor (Aldosterone receptor)** in the late distal tubule and collecting duct. **Why Hyperkalemia is Correct:** Aldosterone normally promotes the reabsorption of sodium ($Na^+$) and the excretion of potassium ($K^+$) and hydrogen ions ($H^+$). By blocking this receptor, Spironolactone prevents $K^+$ secretion into the tubular lumen. This leads to the retention of potassium in the blood, resulting in **Hyperkalemia**, its most significant and potentially life-threatening side effect. **Analysis of Incorrect Options:** * **A. Alkalosis:** Spironolactone causes **Metabolic Acidosis** (not alkalosis) because it inhibits the excretion of $H^+$ ions. * **B. Hirsutism:** Spironolactone actually has **anti-androgenic** properties (it blocks androgen receptors and inhibits steroidogenesis). Therefore, it is used to *treat* hirsutism in conditions like PCOS. A common side effect in males, however, is **gynecomastia**. * **D. Hyperglycemia:** This is a classic side effect of **Thiazides and Loop diuretics**, which can impair insulin release. Spironolactone does not typically affect blood glucose levels. **High-Yield Clinical Pearls for NEET-PG:** * **Eplerenone** is a more selective aldosterone antagonist with fewer endocrine side effects (less risk of gynecomastia) compared to Spironolactone. * **Drug Interaction:** Avoid combining Spironolactone with ACE inhibitors or ARBs, as this significantly increases the risk of severe hyperkalemia. * **Indication of Choice:** It is the diuretic of choice for patients with **Cirrhosis with Ascites** and is proven to reduce mortality in **Chronic Heart Failure (NYHA Class II-IV)**.

Q: A 64-year-old man with heart failure is recently started on 80 mg/day of furosemide. He now feels weak and tired, but notes that his heart failure symptoms have improved. There is no change in his urine output and he gets a good diuretic response every time he takes his furosemide. Which are the characteristic ECG findings?

lengthened QU interval. ### Explanation **Correct Answer: C. Lengthened QU interval** **1. Underlying Medical Concept:** Furosemide is a potent loop diuretic that inhibits the Na⁺/K⁺/2Cl⁻ symporter in the thick ascending limb of the Loop of Henle. A common and significant side effect of loop diuretics is **hypokalemia** (low serum potassium). In hypokalemia, the ECG undergoes characteristic changes due to delayed ventricular repolarization. The most classic finding is the appearance of **prominent U waves**. As the U wave becomes more pronounced and the T wave flattens, the T and U waves often merge. This creates the appearance of a **"lengthened QU interval"** (or a pseudo-prolonged QT interval), which is a hallmark of potassium depletion. The patient’s symptoms of weakness and fatigue are clinical indicators of this electrolyte imbalance. **2. Why the other options are incorrect:** * **A & B (PR Interval):** Changes in the PR interval are typically associated with calcium abnormalities or AV nodal blocks (e.g., Digoxin toxicity), not primarily with the hypokalemia caused by diuretics. * **D (Shortened QT interval):** A shortened QT interval is characteristic of **hypercalcemia**. In contrast, hypokalemia (and hypocalcemia) typically leads to a prolonged appearance of the repolarization phase (prolonged QU/QT). **3. NEET-PG High-Yield Pearls:** * **ECG findings in Hypokalemia:** Flattening/inversion of T waves, ST-segment depression, prominent U waves, and QU prolongation. * **Loop Diuretics Side Effects (Mnemonic: OH DANG!):** **O**totoxicity, **H**ypokalemia, **D**ehydration, **A**llergy (sulfa), **N**ephritis (interstitial), **G**out (hyperuricemia). * **Metabolic state:** Loop diuretics cause **Hypokalemic Metabolic Alkalosis**. * **U wave:** A positive deflection after the T wave, representing slow repolarization of Purkinje fibers. It is most visible in precordial leads V2–V4.

Q: What is the mechanism of action of furosemide in left ventricular failure (LVF)?

Inhibitor of Na-K-Cl ion symporter. **Mechanism of Action:** Furosemide is a potent **Loop Diuretic**. Its primary mechanism involves the inhibition of the **Naⁱ-Kⁱ-2Clⁱ symporter (NKCC2)** [1] located in the luminal membrane of the **Thick Ascending Limb (TAL)** of the Henle’s loop [2]. By blocking this transporter, it prevents the reabsorption of these electrolytes, leading to profound diuresis and natriuresis [3]. **Role in Left Ventricular Failure (LVF):** In acute LVF (Pulmonary Edema), furosemide acts via two distinct phases [4]: 1. **Immediate Effect (Vascular):** It causes rapid **venodilation** (mediated by prostaglandins), which increases venous capacitance and decreases preload. This provides symptomatic relief even before the onset of diuresis. 2. **Delayed Effect (Renal):** It reduces fluid overload through diuresis, further decreasing the workload on the failing heart. **Analysis of Incorrect Options:** * **B. Aldosterone antagonist:** This describes **Spironolactone** or Eplerenone, which act on the distal tubule and collecting ducts. * **C. Mercurial derivative:** These are obsolete diuretics (e.g., Mersalyl) rarely used today due to toxicity. * **D. Carbonic anhydrase inhibitor:** This describes **Acetazolamide**, which acts on the proximal convoluted tubule and is primarily used for glaucoma or altitude sickness, not LVF [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Action:** Thick Ascending Limb (TAL) – the "diluting segment." * **Side Effects (The "Hypo"s):** Hypokalemia, Hypomagnesemia, Hypocalcemia (Loop loses Calcium), and Hyperuricemia. * **Ototoxicity:** Furosemide can cause dose-dependent hearing loss, especially when combined with aminoglycosides [2]. * **Drug of Choice:** Furosemide is the DOC for **Acute Pulmonary Edema** and edema associated with CHF, Cirrhosis, and Renal failure [4].

Q: Which of the following thiazide diuretics remains active when the Glomerular Filtration Rate (GFR) is 30-40 mL/min?

Metolazone. ### Explanation\n\n**1. Why Metolazone is Correct:**\nMost thiazide diuretics lose their efficacy when the Glomerular Filtration Rate (GFR) falls below **30–40 mL/min** [1], [2]. This is because they must be secreted into the tubular lumen to act on the Na⁺-Cl⁻ symporter in the distal convoluted tubule; in renal failure, their delivery to the site of action is significantly impaired. **Metolazone** (and to some extent Indapamide) is a "thiazide-like" diuretic that is uniquely potent. It maintains its diuretic efficacy even in advanced renal insufficiency (GFR as low as 10–20 mL/min) [1].\n\n**2. Why the Other Options are Incorrect:**\n* **Benzthiazide & Chlorothiazide:** These are classical thiazides. They are ineffective in patients with significant renal impairment (GFR < 30 mL/min) because they cannot reach therapeutic concentrations in the tubular fluid [1].\n* **Chlorthalidone:** While it is highly potent and has a long half-life (making it a preferred agent for hypertension), it generally loses its effectiveness as a diuretic when renal function is significantly compromised, unlike Metolazone [1].\n\n**3. High-Yield Clinical Pearls for NEET-PG:**\n* **Synergistic Effect:** Metolazone is frequently added to Loop diuretics (e.g., Furosemide) to overcome **"diuretic resistance"** in patients with refractory edema or congestive heart failure. This is known as **Sequential Nephron Blockade**.\n* **Metabolic Side Effects:** Remember the mnemonic **"Hyper GLUC"** for thiazides: Hyper**G**lycemia, Hyper**L**ipidemia, Hyper**U**ricemia, and Hyper**C**alcemia.\n* **Hypokalemia:** Like loop diuretics, thiazides cause potassium wasting [1].\n* **Indapamide:** Another thiazide-like diuretic often preferred in diabetics as it is considered "metabolically neutral."

Q: Which of the following diuretics is used in the given condition?

Furosemide. ***Furosemide*** - **Loop diuretic** that acts on the **thick ascending limb of Henle** to rapidly promote **natriuresis** and **diuresis**, effectively reducing **preload** in acute pulmonary edema. - First-line treatment for **acute heart failure** with pulmonary edema due to its **rapid onset** and powerful fluid removal capacity. *Thiazide* - **Thiazide diuretics** are less potent and have a **slower onset** of action, making them unsuitable for acute pulmonary edema emergencies. - Primarily used for **chronic hypertension** and **mild heart failure**, not for rapid fluid overload management. *Acetazolamide* - **Carbonic anhydrase inhibitor** with weak diuretic effect, primarily used for **glaucoma**, **altitude sickness**, and **metabolic alkalosis**. - Ineffective for managing **acute fluid overload** due to its limited natriuretic capacity and potential to cause **metabolic acidosis**. *Neomycin* - **Aminoglycoside antibiotic** with no diuretic properties, used to reduce **ammonia-producing bacteria** in hepatic encephalopathy. - Completely unrelated to **fluid management** and would be contraindicated due to potential **nephrotoxicity** in heart failure patients.

Q: Thiazides cause all the following side-effects except-

Metabolic acidosis. **Explanation:** Thiazide diuretics act on the **Distal Convoluted Tubule (DCT)** by inhibiting the $Na^+/Cl^-$ symporter. This mechanism leads to a specific pattern of electrolyte and acid-base disturbances. **Why Metabolic Acidosis is the correct answer:** Thiazides do **not** cause metabolic acidosis; instead, they cause **Metabolic Alkalosis**. By increasing sodium delivery to the collecting ducts, they stimulate the exchange of $Na^+$ for $H^+$ and $K^+$. The loss of $H^+$ ions in the urine leads to an increase in serum bicarbonate levels (contraction alkalosis). In contrast, metabolic acidosis is a side effect of Carbonic Anhydrase inhibitors (like Acetazolamide) or Potassium-sparing diuretics. **Analysis of Incorrect Options:** * **Hypercalcemia:** Thiazides increase calcium reabsorption in the DCT (unlike loop diuretics which cause hypocalcemia). This makes them useful in treating idiopathic hypercalciuria and calcium stones. * **Hypokalemia:** Increased sodium delivery to the late distal tubule promotes $K^+$ secretion into the lumen, leading to potassium depletion. * **Metabolic Alkalosis:** As explained above, the loss of $H^+$ and $Cl^-$ ions results in an alkalotic state. **High-Yield Clinical Pearls for NEET-PG:** * **The "Hyper" Mnemonic:** Thiazides cause **Hyper**glycemia, **Hyper**uricemia (can precipitate Gout), **Hyper**lipidemia, and **Hyper**calcemia. * **The "Hypo" Mnemonic:** They cause **Hypo**kalemia, **Hypo**natremia, and **Hypo**magnesemia. * **Drug of Choice:** Thiazides are the first-line treatment for Hypertension in patients with Osteoporosis due to their calcium-sparing effect.

Question 1

Which drug commonly causes gynecomastia?

Accepted Answer

Spironolactone

Answer

Rifampicin

Answer

Penicillin

Answer

Bumetanide

Question 2

Which diuretic can be used in renal failure?

Accepted Answer

Furosemide

Answer

Chlorothiazide

Answer

Mannitol

Answer

Chlorthalidone

Question 3

Which of the following side effects is associated with Spironolactone?

Accepted Answer

Hyperkalemia

Answer

Alkalosis

Answer

Hirsutism

Answer

Hyperglycemia

Question 4

A 64-year-old man with heart failure is recently started on 80 mg/day of furosemide. He now feels weak and tired, but notes that his heart failure symptoms have improved. There is no change in his urine output and he gets a good diuretic response every time he takes his furosemide. Which are the characteristic ECG findings?

Accepted Answer

lengthened QU interval

Answer

shortened PR interval

Answer

lengthened PR interval

Answer

shortening of the QT interval

Question 5

What is the drug of choice for hypertension in a patient with osteoporosis?

Accepted Answer

Thiazide diuretics

Answer

ACE inhibitors

Answer

Beta-blockers

Answer

Loop diuretics

Question 6

What is the mechanism of action of furosemide in left ventricular failure (LVF)?

Accepted Answer

Inhibitor of Na-K-Cl ion symporter

Answer

Aldosterone antagonist

Answer

Mercurial derivative

Answer

Carbonic anhydrase inhibitor

Question 7

A patient arrives in the emergency room in a coma and has a serum Ca 2+ of 4.5 mM. You start a saline infusion of which of the following drugs?

Accepted Answer

Ethacrynic acid

Answer

Calcitonin

Answer

Hydrochlorothiazide

Answer

Spironolactone

Question 8

Which of the following thiazide diuretics remains active when the Glomerular Filtration Rate (GFR) is 30-40 mL/min?

Accepted Answer

Metolazone

Answer

Benzthiazide

Answer

Chlorothiazide

Answer

Chlorthalidone

Question 9

Which of the following diuretics is used in the given condition?

Accepted Answer

Furosemide

Answer

Thiazide

Answer

Acetazolamide

Answer

Neomycin

Question 10

Thiazides cause all the following side-effects except-

Accepted Answer

Metabolic acidosis

Answer

Hypercalcemia

Answer

Hypokalemia

Answer

Metabolic alkalosis

Diuretics — MCQs

Diuretics — MCQs

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