All of the following diuretics increases K+ excretion EXCEPT: March 2013
**Core Concept**
Diuretics are a class of medications that increase urine production by inhibiting sodium reabsorption in the kidneys. Potassium excretion is a secondary effect of diuretic therapy, and some diuretics are more likely to cause hypokalemia (low potassium levels) than others.
**Why the Correct Answer is Right**
The correct answer is the diuretic that does not increase potassium excretion. Diuretics that act on the distal convoluted tubule (DCT) and collecting duct, such as loop diuretics, thiazide diuretics, and potassium-sparing diuretics, tend to increase potassium excretion. However, potassium-sparing diuretics, such as spironolactone and eplerenone, act by inhibiting the aldosterone receptor, which usually leads to increased potassium retention, not excretion.
**Why Each Wrong Option is Incorrect**
**Option A:** Loop diuretics, such as furosemide, increase potassium excretion by inhibiting the Na+/K+/2Cl- cotransporter in the thick ascending limb of the loop of Henle. This leads to increased sodium delivery to the DCT, which in turn increases potassium excretion.
**Option B:** Thiazide diuretics, such as hydrochlorothiazide, increase potassium excretion by inhibiting the Na+/Cl- cotransporter in the DCT, leading to increased sodium delivery to the collecting duct and increased potassium excretion.
**Option C:** Potassium-sparing diuretics, such as spironolactone, actually decrease potassium excretion by inhibiting the aldosterone receptor, leading to increased potassium retention.
**Clinical Pearl / High-Yield Fact**
When using diuretics, it's essential to monitor potassium levels, especially in patients with pre-existing hypokalemia or those taking medications that increase potassium excretion.
**Correct Answer:** C. Potassium-sparing diuretics actually decrease potassium excretion.