Minimum quantity of filtered Na actually excreted is by which of the following diuretie-
**Core Concept**
The minimum quantity of filtered sodium (Na) actually excreted is determined by the balance between sodium reabsorption and excretion in the kidneys. This is primarily regulated by the renin-angiotensin-aldosterone system (RAAS), which controls sodium reabsorption in the distal convoluted tubule and collecting duct.
**Why the Correct Answer is Right**
The correct answer is Loop Diuretics. Loop diuretics, such as furosemide, act on the thick ascending limb of the loop of Henle to inhibit sodium-potassium-chloride (Na-K-Cl) cotransporter 2 (NKCC2). This leads to increased sodium and chloride excretion, making loop diuretics highly effective in promoting diuresis. The minimum quantity of filtered sodium actually excreted is by loop diuretics because they act on the loop of Henle, which is responsible for 25-30% of sodium reabsorption.
**Why Each Wrong Option is Incorrect**
**Option A:** Thiazide diuretics act on the distal convoluted tubule to inhibit sodium-chloride cotransporter (NCC) and are less potent than loop diuretics in promoting diuresis.
**Option B:** Potassium-sparing diuretics, such as spironolactone, act on the collecting duct to inhibit sodium reabsorption, but do not increase sodium excretion as much as loop diuretics.
**Option C:** Osmotic diuretics, such as mannitol, increase sodium excretion by increasing water excretion, but do not act on the loop of Henle.
**Clinical Pearl / High-Yield Fact**
Loop diuretics are highly effective in promoting diuresis, but can lead to hypokalemia and hypomagnesemia due to increased potassium and magnesium excretion.
**Correct Answer: C. Loop diuretics.**