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Monitoring acid-base status is very important in individuals with kidney pathology.

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asked Oct 13 in Biochemistry by Rajesh Bahara

Monitoring acid-base status is very important in individuals with kidney pathology. Which of the following diuretics causes metabolic alkalosis?

  1. (A)  Acetazolamide and potassium-sparing diuretics

  2. (B)  Loop diuretics and acetazolamide

  3. (C)  Loop diuretics and potassium-sparing diuretics

  4. (D)  Loop diuretics and thiazides

  5. (E)  Thiazides and acetazolamide

  6. (F)  Thiazides and potassium-sparing diuretics

 

1 Answer

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Best answer
The correct answer is D.

Thiazides and furosemide lead to metabolic alkalosis. There are two components to the development of metabolic alkalosis: volume depletion and electrolyte imbalance; specifically hypochloremia and hypokalemia. Volume contraction leads to increased sodium reabsorption and bicarbonate retention. The diuretic-induced hypochloremia and hypokalemia lead to persistence of the alkalosis because the hypokalemia causes hydrogen to be exchanged for sodium rather than potassium at the distal convoluted tubule.

Answer A is incorrect. Neither potassium-sparing diuretics nor acetazolamide cause metabolic alkalosis. Potassium-sparing diuretics cause metabolic acidosis by inhibiting sodium-hydrogen exchange channels, and acetazolamide promotes the loss of bicarbonate in the urine, causing metabolic acidosis.

Answer B is incorrect. Acetazolamide inhibits the enzyme carbonic anhydrase, which is important in the reabsorption of sodium, bicarbonate, and chloride at the proximal tubule. Since it promotes the loss of bicarbonate in the urine, it tends to cause metabolic acidosis.

Answer C is incorrect. The potassium-sparing diuretics, such as spironolactone, inhibit aldosterone-sensitive sodium channels that excrete hydrogen or potassium in exchange for sodium. Inhibition of these channels may lead to hyperkalemia and metabolic acidosis.

Answer E is incorrect. Thiazides do cause metabolic alkalosis by causing volume depletion, hypochloremia, and hypokalemia. However, acetazolamide promotes the loss of bicarbonate in the urine, causing metabolic acidosis.

Answer F is incorrect. Thiazides do cause metabolic alkalosis by causing volume depletion, hypochloremia, and hypokalemia. How- ever, potassium-sparing diuretics cause metabolic acidosis by inhibiting sodium-hydrogen exchange channels.
answered Oct 13 by Rajesh Bahara

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