Diuretics and Electrolyte Shifts

A diuretic does more than increase urine volume. The nephron segment it affects determines which electrolytes leave the body, which remain in the circulation, and which complications the nurse should anticipate before the laboratory report returns. | Class | Main site and action | Electrolyte pattern to anticipate | |---|---|---| | Loop diuretics: furosemide, bumetanide, torsemide | Block the Na-K-2Cl cotransporter in the thick ascending limb | Loss of sodium, potassium, chloride, calcium, and magnesium; hypokalemic, hypochloremic metabolic alkalosis | | Thiazide or thiazide-like diuretics: hydrochlorothiazide, chlorthalidone, metolazone | Block the sodium-chloride cotransporter in the distal convoluted tubule | Hyponatremia, hypokalemia, hypochloremic metabolic alkalosis, hypomagnesemia, reduced urinary calcium, possible hypercalcemia | | Potassium-sparing agents: spironolactone, eplerenone, amiloride, triamterene | Reduce aldosterone effect or epithelial sodium entry in the late distal nephron and collecting duct | Potassium retention and hyperkalemia | | Carbonic anhydrase inhibitor: acetazolamide | Reduces proximal bicarbonate and sodium reabsorption | Bicarbonate loss; can counter loop-related alkalosis and augment diuresis | The loop segment normally creates a lumen-positive voltage that drives paracellular calcium and magnesium reabsorption. Blocking it...