Diuretics — MCQs
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Which of the following drugs will act on X to inhibit sugar absorption from the PCT of kidney?
A 42-year old man with history of alcohol dependency presents with progressive abdominal distension. Abdominal examination reveals a shifting dullness. Which one of the following is the most appropriate drug to relieve this abdominal distension?
A 66-year-old male presents to the outpatient cardiology clinic for evaluation of suspected primary hypertension. His blood pressure is elevated to 169/96 mm Hg, and his heart rate is 85/min. Physical examination reveals an overweight male with regular heart and lung sounds. Following repeated elevated blood pressure measurements, the diagnosis is made and the patient is started on hydrochlorothiazide. Of the following options, which is a side effect that one could experience from thiazide-like diuretics?
Which of the following is a carbonic anhydrase inhibitor?
Hydrochlorothiazide works by inhibiting
Which one of the following is not a clinical use of spironolactone?
Which of the following diuretics is contraindicated in Hepatic coma?
What is the effect of thiazide diuretics on urinary calcium excretion?
Side effects of oral carbonic anhydrase inhibitors include?
Loop and thiazide diuretics commonly cause clinically significant loss of:
Diuretics Indian Medical PG Practice Questions and MCQs
Question 141: Which of the following drugs will act on X to inhibit sugar absorption from the PCT of kidney?
- A. Dapagliflozin (Correct Answer)
- B. Hydrochlorothiazide
- C. Furosemide
- D. Spironolactone
Explanation: ***Dapagliflozin*** - The image shows glucose reabsorption in the **proximal tubule**, with 90% in the S1/S2 segments and 10% in the S3 segment. The "X" points to the **SGLT2 transporter** in the proximal tubule. - **Dapagliflozin** is an **SGLT2 inhibitor** that blocks glucose reabsorption, leading to increased glucose excretion in urine. - Used in **type 2 diabetes mellitus** and has cardiovascular and renal protective effects. *Furosemide* - A **loop diuretic** that acts on the **thick ascending limb of Loop of Henle**, not the proximal tubule. - Inhibits the **Na-K-2Cl cotransporter**, not involved in glucose reabsorption. *Hydrochlorothiazide* - A **thiazide diuretic** that acts on the **distal convoluted tubule (DCT)**. - Inhibits the **Na-Cl cotransporter**, not involved in glucose reabsorption. *Spironolactone* - A **potassium-sparing diuretic** that acts on the **collecting duct**. - Works as an **aldosterone antagonist**, not involved in glucose reabsorption.
Question 142: A 42-year old man with history of alcohol dependency presents with progressive abdominal distension. Abdominal examination reveals a shifting dullness. Which one of the following is the most appropriate drug to relieve this abdominal distension?
- A. Lactulose
- B. Spironolactone (Correct Answer)
- C. Propranolol
- D. Octreotide
Explanation: **Spironolactone** - **Spironolactone** is an **aldosterone antagonist**, which is the **first-line diuretic** used in the management of **ascites** due to **cirrhosis**, often developing secondary to alcohol dependency. - It works by blocking aldosterone receptors in the **renal collecting duct**, leading to increased sodium and water excretion while conserving potassium, effectively reducing fluid accumulation. *Lactulose* - **Lactulose** is a non-absorbable disaccharide primarily used to treat and prevent **hepatic encephalopathy** by reducing ammonia levels. - It does not directly relieve abdominal distension caused by ascites, and its use is unrelated to fluid overload. *Propranolol* - **Propranolol** is a **non-selective beta-blocker** used to reduce **portal pressure** and prevent **variceal bleeding** in patients with cirrhosis. - While it addresses a complication of chronic liver disease, it does not directly manage or relieve ascites. *Octreotide* - **Octreotide** is a **somatostatin analog** used to treat complications like **acute variceal bleeding** or **hepatic encephalopathy** by reducing splanchnic blood inflow. - It is not indicated for the management of ascites or relief of abdominal distension caused by fluid accumulation.
Question 143: A 66-year-old male presents to the outpatient cardiology clinic for evaluation of suspected primary hypertension. His blood pressure is elevated to 169/96 mm Hg, and his heart rate is 85/min. Physical examination reveals an overweight male with regular heart and lung sounds. Following repeated elevated blood pressure measurements, the diagnosis is made and the patient is started on hydrochlorothiazide. Of the following options, which is a side effect that one could experience from thiazide-like diuretics?
- A. Hyperuricemia (Correct Answer)
- B. Hyperkalemia
- C. Hypocalcemia
- D. Hypernatremia
- E. Hypoglycemia
Explanation: ***Hyperuricemia*** - Thiazide diuretics inhibit the secretion of **uric acid** in the renal tubules. [1] - This can lead to increased serum uric acid levels, potentially exacerbating or precipitating **gout**. [1] *Hyperkalemia* - Thiazide diuretics work by inhibiting the Na+/Cl- cotransporter in the **distal convoluted tubule**, which leads to increased sodium delivery to the collecting duct. [1] - This promotes the excretion of potassium, resulting in **hypokalemia**, not hyperkalemia. *Hypocalcemia* - Thiazide diuretics decrease the excretion of **calcium** by increasing its reabsorption in the distal convoluted tubule. [1], [2] - This effect leads to **hypercalcemia**, not hypocalcemia, and can be beneficial in patients with osteoporosis. [2] *Hypernatremia* - Thiazide diuretics increase the excretion of **sodium** along with water. - This effect tends to cause **hyponatremia**, not hypernatremia, due to increased urinary sodium loss and water retention relative to sodium. [2]
Question 144: Which of the following is a carbonic anhydrase inhibitor?
- A. Hydrochlorothiazide
- B. Mannitol
- C. Furosemide
- D. Acetazolamide (Correct Answer)
Explanation: ***Acetazolamide*** - Acetazolamide is a classic example of a **carbonic anhydrase inhibitor**, primarily used as a diuretic and for managing **glaucoma** and **altitude sickness**. - It works by inhibiting the enzyme **carbonic anhydrase** in the **proximal renal tubule**, reducing bicarbonate reabsorption and thus promoting diuresis. *Hydrochlorothiazide* - Hydrochlorothiazide is a **thiazide diuretic** that acts on the **distal convoluted tubule** to inhibit the reabsorption of sodium and chloride. - It is not a carbonic anhydrase inhibitor. *Mannitol* - Mannitol is an **osmotic diuretic** that works in the **proximal tubule** and **descending limb of Henle's loop** by creating an osmotic gradient. - It is not a carbonic anhydrase inhibitor and functions by drawing water into the renal tubule, leading to increased urine output. *Furosemide* - Furosemide is a **loop diuretic** that acts on the **thick ascending limb of the loop of Henle** by inhibiting the Na+-K+-2Cl- cotransporter. - It is one of the most potent diuretics but does not inhibit carbonic anhydrase.
Question 145: 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 146: Which one of the following is not a clinical use of spironolactone?
- A. Pulmonary edema (Correct Answer)
- B. Congestive heart failure
- C. Hypertension
- D. To counteract hypokalemia due to thiazide diuretics
Explanation: ***Pulmonary edema*** - While spironolactone is a **diuretic**, its onset of action is relatively slow (days to weeks), making it unsuitable for the acute management of **pulmonary edema**, which requires rapid fluid removal. - For acute pulmonary edema, fast-acting loop diuretics like **furosemide** are preferred due to their potent and rapid diuresis. *Congestive heart failure* - Spironolactone is a **potassium-sparing diuretic** and an **aldosterone antagonist**, which improves outcomes in **congestive heart failure** by reducing fluid retention, myocardial fibrosis, and sympathetic activation. - It specifically helps in preventing **cardiac remodeling** and has been shown to reduce mortality in patients with heart failure. *Hypertension* - Spironolactone is used as an **adjunctive treatment for hypertension**, particularly in cases of **resistant hypertension** or when there is evidence of primary hyperaldosteronism. - It helps lower **blood pressure** by blocking aldosterone's effects, leading to increased sodium and water excretion. *To counteract hypokalemia due to thiazide diuretics* - As a **potassium-sparing diuretic**, spironolactone directly counteracts the **hypokalemia** (low potassium) that can be induced by other diuretics, such as **thiazide diuretics** and **loop diuretics**. - Its mechanism involves blocking **aldosterone receptors** in the collecting duct, reducing potassium secretion and sodium reabsorption.
Question 147: Which of the following diuretics is contraindicated in Hepatic coma?
- A. Bumetanide
- B. Furosemide
- C. Acetazolamide (Correct Answer)
- D. Spironolactone
Explanation: ***Acetazolamide*** - **Acetazolamide** inhibits carbonic anhydrase, leading to increased bicarbonate excretion and metabolic acidosis. In patients with **hepatic coma**, this can worsen the condition by impairing the liver's ability to convert ammonia to urea, leading to increased levels of **ionized ammonia** that can cross the blood-brain barrier. - The resulting **metabolic acidosis** can also interfere with the kidney's response to ammonia, further exacerbating the **hepatic encephalopathy**. *Bumetanide* - **Bumetanide** is a loop diuretic that acts on the **thick ascending limb of the loop of Henle** to inhibit sodium, potassium, and chloride reabsorption. - It does not directly exacerbate **hepatic encephalopathy** through metabolic acidosis in the same way as acetazolamide. *Furosemide* - **Furosemide** is a loop diuretic similar to bumetanide, acting on the **thick ascending limb** to promote diuresis. - While aggressive diuresis with furosemide in critical patients can sometimes lead to **volume depletion** and electrolyte imbalances that may indirectly affect liver function, it does not directly worsen **hepatic coma** by altering systemic acid-base balance and ammonia detoxification like acetazolamide. *Spironolactone* - **Spironolactone** is an **aldosterone antagonist** and a potassium-sparing diuretic, commonly used in liver cirrhosis with ascites. - It does not directly cause **metabolic acidosis** or increase ionized ammonia levels; in fact, by improving fluid balance, it can sometimes help manage complications of liver disease.
Question 148: What is the effect of thiazide diuretics on urinary calcium excretion?
- A. Increase excretion
- B. Decrease excretion (Correct Answer)
- C. No effect
- D. Variable effect
Explanation: ***Decrease excretion*** - Thiazide diuretics work by inhibiting the **sodium-chloride cotransporter (NCC)** in the **distal convoluted tubule** of the nephron. - This action leads to increased reabsorption of calcium in the distal tubule via **enhanced activity of the apical calcium channels (TRPV5)** and **basolateral Na+/Ca2+ exchanger (NCX1)**, thereby **decreasing urinary calcium excretion**. - This effect is clinically utilized in patients with **recurrent calcium kidney stones** and **hypercalciuria**. *Increase excretion* - Loop diuretics, like furosemide, block the **Na-K-2Cl cotransporter (NKCC2)** in the thick ascending limb of the loop of Henle, which is associated with **increased calcium excretion**. - Thiazide diuretics have the opposite effect on calcium handling compared to loop diuretics. *No effect* - This is incorrect because thiazide diuretics have a **well-documented and clinically significant effect** on calcium excretion. - The calcium-retaining effect is **consistent and predictable**, not absent. *Variable effect* - The effect of thiazides on calcium is **not variable** but rather **consistent and dose-dependent** in decreasing urinary calcium excretion. - This is a **primary pharmacological action**, not a variable or secondary effect.
Question 149: Side effects of oral carbonic anhydrase inhibitors include?
- A. Paresthesia (Correct Answer)
- B. Hyperkalemia
- C. Insomnia
- D. Weight gain
Explanation: ***Paresthesia*** - **Paresthesia** (tingling sensation, especially in fingers, toes, and perioral region) is one of the **most common side effects** of carbonic anhydrase inhibitors like acetazolamide - Occurs due to **systemic metabolic acidosis** and altered neuronal excitability from pH shifts and electrolyte changes - This symptom is so common that patients should be counseled about it before starting therapy *Hyperkalemia* - Carbonic anhydrase inhibitors cause **hypokalemia (potassium wasting)**, NOT hyperkalemia - Mechanism: Increased sodium delivery to distal tubule → increased Na-K exchange → urinary potassium loss - Although metabolic acidosis can shift potassium out of cells, the **diuretic effect predominates**, leading to net potassium loss *Insomnia* - **Not a recognized side effect** of carbonic anhydrase inhibitors - Patients may actually experience **fatigue or drowsiness** rather than insomnia - No direct pharmacological mechanism links carbonic anhydrase inhibition to sleep disturbances *Weight gain* - Carbonic anhydrase inhibitors have a **diuretic effect** causing fluid and sodium loss - Patients typically experience **weight loss or stable weight**, not weight gain - Weight gain is associated with fluid-retaining medications, which is the opposite effect of diuretics
Question 150: Loop and thiazide diuretics commonly cause clinically significant loss of:
- A. Sodium
- B. Calcium
- C. Potassium (Correct Answer)
- D. Iron
Explanation: ***Potassium*** - Loop diuretics (e.g., furosemide) and thiazide diuretics (e.g., hydrochlorothiazide) inhibit sodium reabsorption in the renal tubules, leading to **increased urinary potassium excretion**. - This results in **hypokalemia**, a clinically significant side effect that requires monitoring and often necessitates **potassium supplementation** or the addition of **potassium-sparing diuretics** (e.g., spironolactone, amiloride). - Hypokalemia can cause muscle weakness, cardiac arrhythmias, and increased digitalis toxicity. *Sodium* - While diuretics do increase sodium excretion (their primary therapeutic mechanism), the question focuses on **clinically significant electrolyte loss** that requires intervention. - Sodium loss is the intended therapeutic effect for volume reduction, not typically considered a problematic "side effect." *Calcium* - **Loop diuretics** increase calcium excretion (useful in hypercalcemia treatment). - **Thiazide diuretics** actually decrease calcium excretion (can increase serum calcium, useful in osteoporosis). - The effects are variable depending on diuretic class. *Iron* - Diuretics do not directly affect iron excretion or absorption. - Iron balance is regulated primarily through intestinal absorption, not renal excretion.
Practice by Chapter
Carbonic Anhydrase Inhibitors
Practice Questions
Loop Diuretics
Practice Questions
Thiazide and Thiazide-Like Diuretics
Practice Questions
Potassium-Sparing Diuretics
Practice Questions
Carbonic Anhydrase Inhibitors
Practice Questions
Osmotic Diuretics
Practice Questions
Combination Diuretic Therapy
Practice Questions
Diuretics in Heart Failure
Practice Questions
Diuretics in Hypertension
Practice Questions
Diuretics in Renal Disorders
Practice Questions
Adverse Effects and Drug Interactions
Practice Questions
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