This condition occurs in the diuretic phase of acute tubular necrosis, postobstructive diuresis, and renal tubular acidosis. Diuretics decrease the renal threshold for magnesium reabsorption in addition to wasting of potassium and calcium. Pentamidine and some antibiotics also cause renal magnesium wasting. Fluoride poisoning similarly causes hypomagnesemia. Endocrine disorders may cause hypomagnesemia.
Primary aldosteronism decreases magnesium levels by increasing renal flow.
Hypoparathyroidism and hyperthyroidism may cause renal wasting. Osmotic diuresis results in magnesium loss in the kidney. Diabetics, especially those patients with poor glucose control, develop hypomagnesemia from a glucose-induced osmotic diuresis. Alcoholics become hypomagnesemic partially by an osmotic diuresis from alcohol. Urinary losses have been reported to be 2-3 times control values.