Alteration in Mg²⁺ content of red blood cells from patients with diuretic therapy

Abstract

Hypomagnesemia can cause ventricular tachycardia, cardiac necrosis, or torsades de pointes. Diuretic treatment can result in Mg²⁺ depletion, as many diuretics inhibit the reabsorption of filtered Mg²⁺ in the proximal or distal tubule. As plasma Mg²⁺ constitutes only about 3% of total body Mg²⁺ stores, intracellular Mg²⁺ determinations may be more useful for assessing total body Mg²⁺ content. Therefore we studied the effect of a thiazide diuretic (trichlormethiazide 4 mg/day), a combination of a thiazide and a potassium-sparing diuretic (trichlormethiazide and amiloride 2 mg/day each), and the loop diuretic piretanide (6 mg/day) on intracellular Mg²⁺ in patients with mild essential hypertension before and after 6 and 10 weeks of therapy. Mg²⁺ measurements were performed in blood plasma and in red blood cells by atomic absorption spectroscopy, using a Video 12 apparatus. There was a significant decrease in intracellular Mg²⁺ content under trichlormethiazide therapy (p<0.05). Furthermore, our results show that diuretic treatment with a combination of a thiazide and a potassium-sparing diuretic or with the loop diuretic piretanide may have the advantage of avoiding intracellular Mg²⁺ depletion.