Diuretics in Renal Disorders — MCQs

10 questions

A patient with hypertension, peripheral edema, and chronic kidney disease (CKD) presents for management. Which of the following medications would be the best choice?

Thiazide diuretics can be used for the treatment of all of these conditions EXCEPT :

Hydrochlorothiazide works by inhibiting

All of the following diuretics increase K+ excretion EXCEPT:

In the presence of renal failure, which of the following should not be given?

In a patient on cisplatin therapy, which of the following diuretics would be preferred?

In which segment of the nephron does ethacrynic acid exert its diuretic action?

Potassium-sparing diuretics act at the level of

Which of the following drugs decreases free water clearance?

Q10

All the following adverse effects can be caused by Loop Diuretics EXCEPT -

Diuretics in Renal Disorders Indian Medical PG Practice Questions and MCQs

Question 1: A patient with hypertension, peripheral edema, and chronic kidney disease (CKD) presents for management. Which of the following medications would be the best choice?

A. Aliskiren
B. Beta blocker
C. Prazosin
D. Chlorthalidone (Correct Answer)
E. Furosemide

Explanation: ***Chlorthalidone*** - **Chlorthalidone** is a **thiazide-type diuretic** that is effective in managing hypertension and associated edema, even in patients with moderate CKD (eGFR >30 mL/min/1.73m²). - Its long duration of action and proven cardiovascular benefits make it a good choice for hypertension control in this clinical context. - **Superior to loop diuretics for blood pressure control** and has better evidence for reducing cardiovascular events. *Aliskiren* - **Aliskiren** is a **direct renin inhibitor** that blocks the renin-angiotensin-aldosterone system (RAAS). - However, in patients with CKD, particularly those with existing hypertension and peripheral edema, it is generally **not preferred due to potential risks** of hyperkalemia, renal impairment, and hypotension, especially when combined with ACE inhibitors or ARBs. *Beta blocker* - While **beta-blockers** can treat hypertension, they are **not the first-line choice** for patients with both hypertension and significant peripheral edema. - They also have potential side effects like bradycardia, fatigue, and bronchospasm, and may mask symptoms of hypoglycemia in diabetic patients. *Prazosin* - **Prazosin** is an **alpha-1 adrenergic blocker** that can reduce blood pressure but is primarily used for **hypertension with benign prostatic hyperplasia (BPH)** due to its dilating effect on the bladder neck. - It's **not typically a first-line agent** for essential hypertension with peripheral edema and carries a risk of **first-dose syncope**. *Furosemide* - **Furosemide** is a **loop diuretic** that is more effective than thiazides for managing edema, especially in severe CKD (eGFR <30). - However, for **blood pressure control** in patients with moderate CKD and edema, **thiazide-type diuretics like chlorthalidone are preferred** due to their superior antihypertensive efficacy and cardiovascular benefits. - Loop diuretics have a shorter duration of action and are less effective for chronic hypertension management.

Question 2: Thiazide diuretics can be used for the treatment of all of these conditions EXCEPT :

A. Hypertension
B. Hyperlipidemia (Correct Answer)
C. Congestive Heart Failure
D. Idiopathic hypercalciuria with nephrocalcinosis

Explanation: ***Hyperlipidemia***- Thiazide diuretics are **not used to treat hyperlipidemia** and can sometimes have a mild **adverse effect of causing dyslipidemia** (increased LDL cholesterol and triglycerides).- Their mechanism of action primarily involves diuresis and vasodilation, not directly affecting lipid metabolism.*Hypertension*- Thiazide diuretics are **first-line agents** for the treatment of hypertension, especially for uncomplicated cases [3].- They reduce blood pressure by increasing sodium and water excretion, leading to a decrease in **extracellular fluid volume** and peripheral vascular resistance [2].*Congestive Heart Failure*- Thiazide diuretics are effective in managing **fluid overload** and **edema** associated with congestive heart failure [2].- While loop diuretics are often preferred for severe heart failure due to their greater diuretic potency, thiazides can be beneficial in milder cases or as adjuncts.*Idiopathic hypercalciuria with nephrocalcinosis*- Thiazide diuretics are used to treat **idiopathic hypercalciuria** because they promote **calcium reabsorption** in the renal tubules, thereby reducing urinary calcium excretion [1].- This property helps prevent the formation of calcium-containing kidney stones and can be beneficial in patients with **nephrocalcinosis**.

Question 3: Hydrochlorothiazide works by inhibiting

A. Na+ Cl pump in late DCT
B. Na+ K+ 2Cl pump in descending limb of loop of Henle
C. Na+ K+ 2Cl pump in ascending limb of loop of Henle
D. Na+ Cl pump in early DCT (Correct Answer)

Explanation: ***Na+ Cl pump in early DCT*** - **Hydrochlorothiazide** is a **thiazide diuretic** that acts primarily on the **early distal convoluted tubule (DCT)**. - It inhibits the **sodium-chloride cotransporter (NCC)**, leading to increased excretion of sodium, chloride, and water. *Na+ Cl pump in late DCT* - The **late DCT** and collecting duct are primarily involved in fine-tuning sodium reabsorption, influenced by **aldosterone**, not the primary site of action for thiazides. - The **epithelial sodium channel (ENaC)** and Na+/K+-ATPase are more prominent here. *Na+ K+ 2Cl pump in descending limb of loop of Henle* - The **descending limb of the loop of Henle** is primarily permeable to water, with no active ion pumps like **Na+ K+ 2Cl pump**. - Its main function is to concentrate the urine by allowing water to move out. *Na+ K+ 2Cl pump in ascending limb of loop of Henle* - **Furosemide** and other **loop diuretics** act on the **Na+ K+ 2Cl cotransporter (NKCC2)** in the **thick ascending limb of the loop of Henle**, not hydrochlorothiazide. - Inhibition here prevents significant reabsorption of sodium, potassium, and chloride, leading to potent diuresis.

Question 4: All of the following diuretics increase K+ excretion EXCEPT:

A. Acetazolamide
B. Triamterene (Correct Answer)
C. Thiazide
D. Furosemide

Explanation: ***Triamterene*** - **Triamterene** is a **potassium-sparing diuretic** that blocks epithelial sodium channels (ENaC) in the collecting duct, thereby reducing sodium reabsorption and potassium secretion. - Unlike most other diuretics, it causes **decreased K+ excretion** and can lead to hyperkalemia. *Acetazolamide* - **Acetazolamide** is a **carbonic anhydrase inhibitor** that acts in the proximal tubule, inhibiting bicarbonate reabsorption. - This leads to increased delivery of sodium and bicarbonate to the collecting duct, which enhances **potassium secretion** and increases K+ excretion. *Thiazide* - **Thiazide diuretics** (e.g., hydrochlorothiazide) act by inhibiting the Na+/Cl- cotransporter in the **distal convoluted tubule**. - This increases the delivery of sodium to the collecting duct, which stimulates the exchange of sodium for **potassium**, leading to increased K+ excretion and hypokalemia. *Furosemide* - **Furosemide** is a **loop diuretic** that inhibits the Na+/K+/2Cl- cotransporter in the **thick ascending limb of the loop of Henle**. - This prevents the reabsorption of these ions, leading to increased delivery of sodium to the collecting duct, which promotes **potassium secretion** and increased K+ excretion.

Question 5: In the presence of renal failure, which of the following should not be given?

A. Bumetanide
B. Furosemide
C. Spironolactone (Correct Answer)
D. None of the options

Explanation: ***Spironolactone*** - **Spironolactone** is an **aldosterone antagonist**, a **potassium-sparing diuretic**, which can cause **hyperkalemia**, especially in patients with **renal impairment** where potassium excretion is already compromised - Due to the risk of severe **hyperkalemia**, which can lead to life-threatening **cardiac arrhythmias**, spironolactone is **contraindicated** or used with extreme caution in **renal failure** - In renal failure, the kidneys cannot adequately excrete potassium, and adding a potassium-sparing diuretic significantly increases the risk of dangerous hyperkalemia *Bumetanide* - **Bumetanide** is a **loop diuretic** that primarily acts on the **ascending limb of the loop of Henle** to inhibit sodium and chloride reabsorption - While its efficacy may be reduced in severe renal failure, it is still commonly used at higher doses and can be effective in managing fluid overload in these patients - Loop diuretics remain the mainstay of diuretic therapy in renal failure, unlike potassium-sparing diuretics *Furosemide* - **Furosemide** is another **loop diuretic** that is often used in patients with **renal failure** to promote diuresis and manage fluid overload - Even with impaired kidney function, it can still exert its diuretic effect, although higher doses may be required - It does not cause significant potassium retention and is safe to use in renal failure *None of the options* - This option is incorrect because **spironolactone** is specifically contraindicated in patients with **renal failure** due to the high risk of **hyperkalemia**

Question 6: In a patient on cisplatin therapy, which of the following diuretics would be preferred?

A. Acetazolamide
B. Thiazide
C. Mannitol (Correct Answer)
D. Furosemide

Explanation: ***Mannitol*** - Cisplatin is a highly **nephrotoxic** drug, and mannitol is often co-administered to induce a potent osmotic diuresis, which helps to flush out the drug and its metabolites through the kidney tubules. - This **osmotic diuretic** effect increases urine flow and minimizes the contact time of cisplatin with renal tubular cells, thereby reducing the risk and severity of **acute tubular necrosis (ATN)**. *Acetazolamide* - Acetazolamide is a **carbonic anhydrase inhibitor** primarily used for glaucoma, altitude sickness, and metabolic alkalosis. - It is not typically used to mitigate cisplatin-induced nephrotoxicity, and its mechanism does not directly address the primary toxic effects of cisplatin on renal tubules. *Thiazide* - Thiazide diuretics (e.g., hydrochlorothiazide) work by inhibiting the **sodium-chloride cotransporter** in the distal convoluted tubule. - While they promote diuresis, their effect is generally less potent than loop diuretics or osmotic diuretics, and they do not provide the same protective osmotic effect against cisplatin nephrotoxicity. *Furosemide* - Furosemide is a **loop diuretic** that acts on the thick ascending limb of the loop of Henle, producing significant diuresis. - While it can increase urine output, it does not offer the same **renal protective benefits** as mannitol against cisplatin toxicity and can potentially exacerbate electrolyte imbalances, especially **hypokalemia**, which is a concern with cisplatin.

Question 7: In which segment of the nephron does ethacrynic acid exert its diuretic action?

A. Proximal convoluted tubule
B. Collecting duct
C. Distal convoluted tubule
D. Thick ascending limb of loop of Henle (Correct Answer)

Explanation: ***Thick ascending limb of loop of Henle*** - Ethacrynic acid is a **loop diuretic** that acts by inhibiting the **Na+-K+-2Cl- cotransporter** (NKCC2) in the luminal membrane of the thick ascending limb. - This inhibition prevents the reabsorption of ions, leading to increased excretion of water, sodium, chloride, and potassium. *Proximal convoluted tubule* - The proximal convoluted tubule is the primary site of reabsorption of most filtered substances, but loop diuretics like ethacrynic acid do not primarily act here. - Carbonic anhydrase inhibitors and SGLT2 inhibitors are examples of diuretics that exert their effects in this segment. *Collecting duct* - The collecting duct is the site where aldosterone antagonists (e.g., spironolactone) and epithelial sodium channel (ENaC) inhibitors (e.g., amiloride, triamterene) exert their diuretic effects. - Its primary role involves fine-tuning water reabsorption under the influence of ADH and regulating potassium excretion. *Distal convoluted tubule* - Thiazide diuretics primarily act in the distal convoluted tubule by inhibiting the **Na+-Cl- cotransporter** (NCC). - This segment is responsible for further diluting the urine and reabsorbing a small percentage of filtered sodium and chloride.

Question 8: Potassium-sparing diuretics act at the level of

A. Carbonic anhydrase
B. Aldosterone receptor (Correct Answer)
C. NaCl symporter
D. Na-K pump

Explanation: ***Aldosterone receptor*** - **Potassium-sparing diuretics** include two main classes: 1. **Aldosterone receptor antagonists** (e.g., **spironolactone**, **eplerenone**) that act on **aldosterone receptors** in the collecting tubules 2. **ENaC blockers** (e.g., **amiloride**, **triamterene**) that directly block **epithelial sodium channels (ENaC)** in the collecting duct - Both mechanisms reduce **sodium reabsorption** and **potassium secretion** in the **collecting tubule**, leading to retained potassium. - The aldosterone receptor is the most commonly tested site for this drug class. *Carbonic anhydrase* - **Carbonic anhydrase inhibitors** (e.g., **acetazolamide**) act primarily in the **proximal convoluted tubule**. - They inhibit **bicarbonate reabsorption**, leading to diuresis and metabolic acidosis, and are not considered potassium-sparing. *NaCl symporter* - **Thiazide diuretics** act on the **NaCl symporter (NCC)** in the **distal convoluted tubule**. - They inhibit sodium and chloride reabsorption but do not spare potassium; chronic use can lead to **hypokalemia**. *Na-K pump* - The **Na-K pump** (Na+/K+-ATPase) is found in many cells and maintains ion gradients, but it is not the primary target of potassium-sparing diuretics. - While involved in renal transport, diuretics targeting this pump have different primary mechanisms and therapeutic uses.

Question 9: Which of the following drugs decreases free water clearance?

A. Vincristine (Correct Answer)
B. Vinblastine
C. Chlorpropamide
D. Furosemide

Explanation: ***Vincristine*** - **Vincristine** is a chemotherapeutic agent (vinca alkaloid) that commonly causes **syndrome of inappropriate antidiuretic hormone secretion (SIADH)**. - SIADH leads to **excessive ADH secretion**, causing increased water reabsorption in the collecting ducts. - This results in **decreased free water clearance**, hyponatremia, and concentrated urine with low serum osmolality [2]. *Furosemide* - **Furosemide** is a loop diuretic that inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle. - By reducing solute reabsorption, it impairs the medullary concentration gradient [2]. - This leads to impaired urinary concentration and **increased free water clearance** (dilute urine) [2]. *Vinblastine* - **Vinblastine** is another vinca alkaloid that can also cause SIADH, similar to vincristine. - However, vincristine is more commonly associated with SIADH than vinblastine. *Chlorpropamide* - **Chlorpropamide** is a first-generation sulfonylurea that can potentiate ADH action at the collecting duct [1]. - This leads to increased water reabsorption and decreased free water clearance [1]. - However, this effect is less clinically significant compared to SIADH-inducing drugs.

Question 10: All the following adverse effects can be caused by Loop Diuretics EXCEPT -

A. Hypomagnesemia
B. Hypercalcemia (Correct Answer)
C. Hyperuricemia
D. Hyperglycemia

Explanation: ***Hypercalcemia*** - Loop diuretics inhibit the reabsorption of calcium in the thick ascending limb of the loop of Henle, leading to **increased urinary calcium excretion** and, consequently, **hypocalcemia** [2], [3]. - Therefore, loop diuretics actively decrease calcium levels, so hypercalcemia is not an adverse effect. *Hypomagnesemia* - Loop diuretics interfere with magnesium reabsorption in the thick ascending limb, which can lead to **increased urinary excretion of magnesium** and subsequently cause **hypomagnesemia** [1], [2]. - This effect is clinically significant as it can exacerbate other electrolyte imbalances or cause symptoms like muscle weakness or arrhythmias. *Hyperuricemia* - Loop diuretics can lead to **hyperuricemia** by competing with uric acid for secretion into the renal tubule and by increasing its reabsorption, thereby decreasing its excretion [1]. - This can precipitate or worsen gout, especially in susceptible individuals [1]. *Hyperglycemia* - Loop diuretics, like thiazide diuretics, can cause **hyperglycemia** by impairing insulin secretion and increasing peripheral insulin resistance. - This effect is more pronounced with higher doses and prolonged use, potentially worsening glycemic control in diabetic patients or unmasking latent diabetes.

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