K-sparing diuretics and Mg

Q: Potassium-sparing diuretics ________ magnesium excretion? (select one)

A) enhances

B) reduces

Answer: B

It is true that loop and thiazide diuretics tend to cause urinary magnesium loss. In contrast, potassium-sparing diuretics tend to reduce magnesium excretion. 

Potassium-sparing diuretics which include amiloride, triamterene, and spironolactone decrease sodium entry in the connecting tubule and cortical collecting tubule. This is mediated by epithelial sodium channels in these areas. This effect enhances magnesium reabsorption and so decreases magnesium excretion. 

#nephrology

#electrolytes

References:

Dyckner T, Wester PO, Widman L. Amiloride prevents thiazide-induced intracellular potassium and magnesium losses. Acta Med Scand 1988; 224:25.