Is there any documentation about magnesium therapy in the treatment of hypercalcemia? Could it have

Fråga: Is there any documentation about magnesium therapy in the treatment of hypercalcemia? Could it have deleterious effects?

Background: A 68-year-old cancer patient having lung and liver metastasis (probably originating from pancreas carcinoma) is suffering from hypercalcemia. A homeopath has prescribed magnesium tablets (dose unknown).

Sammanfattning: Magnesium supplementation is not an established therapy in hypercalcemia. There are, however, some theoretical possible advantages and, more importantly, magnesium does not affect calcium excretion. Harmful effects are, therefore, unlikely in patients with normal renal function.

Svar: Textbooks of internal medicine do not mention magnesium supplementation as a means to treat hypercalcemia (1). On the contrary, hypomagnesemia is often associated with severe hypocalcemia and may require separate supplementation (2). Magnesium wasting and ensuing hypomagnesemia can, however, increase tubular reabsorption of calcium and induce hypocalciuria (3). Magnesium loading can reverse the mg/ca reabsorptive balance to normal and restore normocalciuria in this rare condition. In addition, there are some theoretical advantages of magnesium therapy associated with hyperparathyroidism, hypercalcemia or hypercalciuria.

Hypercalcemia and hypercalciuria may be associated with increased risk for calcium precipitation in the urinary system. Recurrent idiopathic renal calculi is indeed an approved indication for magnesium therapy (4). Importantly, magnesium does not affect calcium excretion, but by increasing the magnesium/calcium ratio in urine, decreases the susceptibility to calcium precipitates. In an experimental study with laboratory dogs, hypercalcemic hypertension was suggested to be at least partially related to decreased serum magnesium levels as it was prevented by sustaining serum magnesium (5). Magnesium has also antiarrhythmic properties which may be due to its calcium antagonistic properties in the heart (6). Magnesium hydroxide may also be used as a sole phosphate binder to prevent hyperparathyroidism in patients on maintenance dialysis (7).

Interestingly, intravenous magnesium sulfate which was administered for preeclampsia successfully treated also patient´s hypercalcemia associated with hyperparathyroidism (8). In contrast with this, magnesium therapy has also been associated with precipitation of hypercalcemia in a Crohn´s disease patient receiving vitamin D and calcium supplementation (9). Magnesium sulphate enemas have also been shown to induce hypermagnesemia and hypercalcemia in patients with renal insufficiency (10). 1 Harrison´s, Principles of Internal Medicine, 1987; pages 1870-1875 2 Goodman and Gilman´s the pharmacological basis of therapeutics. Ed by Gilman AG, Rall TW, Nies AS, Taylor P. Pergamon press, New York. 1990; 8th ed: page 705 3 Griffin MD, Muldowney FP: Reversible hypocalciuria with marginal hypercalcaemia in renal magnesium wasting. Quart J Med 1993; 86: 127-134 4 FASS 1995 5 Zawada ET Jr, TerWee JA, McClung DE: Magnesium prevents acute hypercalcemic hypertension. Nephron 1987; 47: 109-114 6 Nattel S, Turmel N, Macleod R, Solymoss BS: Actions of intravenous magnesium on ventricular arrhythmias caused by acute myocardial infarction. J Pharmacol Exp Ther 1991; 259: 939-946 7 Morniere P, Maurouard C, Boudailliez B, Westeel P-F, Boitte F, El Esper N, Compagnon M, Maurel G, Bouillon R, Pamphile R, Fournier A: Prevention of hyperparathyroidism in patients on maintenance dialysis by intravenous 1-alpha-hydroxyvitamin D3 in association with Mg(OH)2 as sole phosphate binder. Nephron 1992; 60: 154-164 8 Rajala B, Abbasi RA, Hutchinson HT, Taylor T: Acute pancreatitis and primary hyperparathyroidism in pregnancy: treatment of hypercalcemia with magnesium sulfate. Obstet Gynecol 1987; 70(Pt 2): 460-362 9 Nanji AA: Symptomatic hypercalcaemia precipitated by magnesium therapy. Postgrad Med J 1985; 61: 47-48 10 Collinson PO, Burroughs AK: Severe hypermagnesaemia due to magnesium sulphate enemas in patients with hepatic coma. Br Med J 1986; 293: 1013-1014