Diuretics Practice Questions

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.

Q: A 32-year-old male patient is treated for hypertension with thiazides. Which of the following adverse effects can occur in this patient?

Impotence. **Explanation:** Thiazide diuretics (e.g., Hydrochlorothiazide, Chlorthalidone) are first-line antihypertensive agents, but they are associated with several metabolic and systemic side effects. **Why Impotence is Correct:** Sexual dysfunction, specifically **erectile dysfunction (impotence)**, is a well-documented side effect of thiazide diuretics. While the exact mechanism is multifactorial, it is thought to involve a decrease in peripheral vascular resistance and a reduction in zinc levels, which is essential for testosterone production. In clinical trials, thiazides are more frequently associated with impotence compared to other antihypertensives like ACE inhibitors or Calcium Channel Blockers. **Analysis of Incorrect Options:** * **A. Hyperkalemic paralysis:** Thiazides inhibit the $Na^+/Cl^-$ symporter in the distal convoluted tubule, increasing sodium delivery to the collecting ducts. This promotes potassium excretion, leading to **hypokalemia**, not hyperkalemia. * **B. Hypouricemia:** Thiazides compete with uric acid for the organic acid secretory secretory pump in the proximal tubule. This leads to decreased uric acid excretion, resulting in **hyperuricemia**, which can precipitate gout. * **C. Hypolipidemia:** Thiazides can cause a transient increase in serum cholesterol and LDL levels (**hyperlipidemia**), though this effect often diminishes with long-term therapy. **High-Yield Clinical Pearls for NEET-PG:** * **The "Hyper" Rule:** Thiazides cause **Hyper**glycemia, **Hyper**uricemia, **Hyper**lipidemia, and **Hyper**calcemia (useful in treating idiopathic hypercalciuria/kidney stones). * **The "Hypo" Rule:** Thiazides cause **Hypo**kalemia, **Hypo**natremia, and **Hypo**magnesemia. * **Chlorthalidone** is currently preferred over Hydrochlorothiazide due to its longer half-life and superior evidence in reducing cardiovascular events.

Q: Which of the following diuretics keeps urine isotonic?

Loop diuretics. **Explanation:** The correct answer is **Loop Diuretics** (e.g., Furosemide). This occurs because loop diuretics inhibit the **Na⁺-K⁺-2Cl⁻ symporter** in the Thick Ascending Limb (TAL) of the Loop of Henle. **Why Loop Diuretics keep urine isotonic:** The TAL is responsible for reabsorbing solutes without water, which creates the **medullary osmotic gradient**. This gradient is essential for both concentrating urine (via ADH) and diluting urine. By blocking solute reabsorption in this segment, loop diuretics abolish the medullary hypertonicity. Consequently, the kidney loses its ability to concentrate or dilute urine, resulting in the excretion of urine that has the same osmolality as plasma (~300 mOsm/L), a phenomenon known as **isosthenuria**. **Why other options are incorrect:** * **Thiazide Diuretics:** These act on the Distal Convoluted Tubule (DCT). They interfere with the kidney’s ability to dilute urine but do **not** affect the medullary gradient. Therefore, the urine remains concentrated (hypertonic) relative to the initial filtrate. * **Carbonic Anhydrase Inhibitors:** These act on the Proximal Convoluted Tubule. While they increase bicarbonate and sodium excretion, they do not disrupt the primary concentrating mechanism of the medulla, thus not resulting in strictly isotonic urine. **High-Yield Clinical Pearls for NEET-PG:** * **"High Ceiling" Diuretics:** Loop diuretics are called this because they have a dose-dependent response with a very high maximal efficacy. * **Calcium Effect:** Loop diuretics cause **hypocalcemia** ("Loops Lose Calcium"), whereas Thiazides cause **hypercalcemia**. * **Drug of Choice:** Loop diuretics are the DOC for acute pulmonary edema and generalized edema (CHF, Nephrotic syndrome).

Q: What is the longest-acting thiazide diuretic?

Chlorthalidone. **Chlorthalidone** is the longest-acting diuretic among the options provided [1]. Although it is chemically a "thiazide-like" diuretic (lacking the benzothiadiazine ring) [2, 3], it shares the same mechanism of action: inhibiting the **Na⁺-Cl⁻ symporter** in the Distal Convoluted Tubule (DCT) [1, 2].**Why Chlorthalidone is the correct answer:**The prolonged duration of action of Chlorthalidone (**48–72 hours**) [2] is primarily due to its high affinity for **carbonic anhydrase** in erythrocytes. This leads to extensive binding within red blood cells, creating a large reservoir that is slowly released into the plasma and delivered to the kidneys. Because of this long half-life, it provides superior 24-hour blood pressure control compared to Hydrochlorothiazide [1].**Analysis of Incorrect Options:** * **A. Chlorthiazide:** This is the prototype thiazide but has a very short half-life (approx. 1.5–2 hours) and low lipid solubility [2]. * **C. Indapamide:** A thiazide-like diuretic with a duration of action of about 24 hours [2, 3]. It is notable for its dual action (diuretic + vasodilation) and is often preferred in patients with renal impairment. * **D. Metolazone:** A potent thiazide-like diuretic with a duration of action of about 12–24 hours [2, 3]. It is unique because it remains effective even when the GFR is low (<30 mL/min).**High-Yield Clinical Pearls for NEET-PG:** * **Potency:** Chlorthalidone is roughly 1.5 to 2 times more potent than Hydrochlorothiazide. * **Drug of Choice:** Recent hypertension guidelines (like ACC/AHA) often prefer Chlorthalidone over other thiazides due to its proven reduction in cardiovascular events. * **Metabolic Side Effects:** All thiazides can cause the "Hyper" states: **Hyper**glycemia, **Hyper**lipidemia, **Hyper**uricemia, and **Hyper**calcemia; and "Hypo" states: **Hypo**kalemia, **Hypo**natremia, and **Hypo**magnesemia.

Q: Which is a safe diuretic in renal dysfunction?

Bumetanide. ### Explanation **Correct Answer: B. Bumetanide** **Why Bumetanide is the correct choice:** Bumetanide is a high-ceiling **Loop Diuretic**. Loop diuretics (including Furosemide and Torsemide) are the diuretics of choice in patients with renal dysfunction (GFR < 30 ml/min). Unlike other classes, loop diuretics maintain their efficacy even when the glomerular filtration rate (GFR) is significantly reduced. They act on the thick ascending limb of the Loop of Henle, which has a large capacity for sodium reabsorption, ensuring a potent natriuretic effect even in failing kidneys. **Why the other options are incorrect:** * **Mannitol (Osmotic Diuretic):** It is contraindicated in established anuria or severe renal failure. It expands extracellular fluid volume, which can lead to acute pulmonary edema and heart failure in patients who cannot excrete the fluid load. * **Chlorthalidone (Thiazide-like Diuretic):** Thiazides and related drugs generally lose their efficacy when the GFR falls below 30 ml/min (with the exception of Metolazone). They are not the preferred agents for fluid management in advanced renal impairment. * **Acetazolamide (Carbonic Anhydrase Inhibitor):** It is a weak diuretic that acts on the proximal tubule. It is avoided in renal failure as it can worsen metabolic acidosis (a common complication of uremia) and has a very limited diuretic effect. **High-Yield Clinical Pearls for NEET-PG:** * **Potency Ratio:** Bumetanide is roughly **40 times more potent** than Furosemide (1 mg Bumetanide ≈ 40 mg Furosemide). * **Metolazone Exception:** While most thiazides fail in renal impairment, **Metolazone** remains effective and is often combined with loop diuretics to overcome "diuretic resistance" (Sequential Nephron Blockade). * **Ototoxicity:** While all loop diuretics can cause ototoxicity, **Ethacrynic acid** is the most ototoxic, while Bumetanide is generally considered to have a lower risk compared to high-dose Furosemide.

Question 1

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

Accepted Answer

Furosemide

Answer

Thiazide

Answer

Acetazolamide

Answer

Neomycin

Question 2

Thiazides cause all the following side-effects except-

Accepted Answer

Metabolic acidosis

Answer

Hypercalcemia

Answer

Hypokalemia

Answer

Metabolic alkalosis

Question 3

Spironolactone is used in the treatment of patients with Conn's syndrome. Which of the following is the most important adverse reaction of spironolactone therapy?

Accepted Answer

Antiandrogen effects

Answer

Cardiac arrhythmia

Answer

Dehydration

Answer

Hyperkalemia

Question 4

A 32-year-old male patient is treated for hypertension with thiazides. Which of the following adverse effects can occur in this patient?

Accepted Answer

Impotence

Answer

Hyperkalemic paralysis

Answer

Hypouricemia

Answer

Hypolipidemia

Question 5

Which of the following diuretics keeps urine isotonic?

Accepted Answer

Loop diuretics

Answer

Thiazide diuretics

Answer

Carbonic anhydrase inhibitors

Answer

None of the above

Question 6

What is the longest-acting thiazide diuretic?

Accepted Answer

Chlorthalidone

Answer

Chlorthiazide

Answer

Indapamide

Answer

Metolazone

Question 7

Which of the following diuretics will continue to induce significant diuresis after return of blood volume to normal levels?

Accepted Answer

furosemide

Answer

hydrochlorothiazide

Answer

spironolactone

Answer

triamterene

Question 8

An 82-year-old man with congestive heart failure and a creatinine clearance (CrCl) of 17 mL/min requires a diuretic for the treatment of peripheral edema. Which of the following diuretics would be most appropriate in this patient?

Accepted Answer

Furosemide

Answer

Hydrochlorothiazide

Answer

Indapamide

Answer

Spironolactone

Question 9

Which is a safe diuretic in renal dysfunction?

Accepted Answer

Bumetanide

Answer

Mannitol

Answer

Chlorthalidone

Answer

Acetazolamide

Question 10

K+ secretion from the loop of Henle is decreased by which of the following medications?

Accepted Answer

Spironolactone

Answer

Furosemide

Answer

Thiazide

Answer

Acetazolamide

Diuretics — MCQs

Diuretics — MCQs

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