Magnesium Deficiency. Etiology and Clinical Spectrum

Abstract

Magnesium deficiency may complicate many diseases. The causes include the following: inadequate intake during starvation or increased requirement during early childhood, pregnancy, or lactation; excessive losses of magnesium as a result of malabsorption from the gastrointestinal tract or from the kidneys during use of diuretics; and to a combination of the two, as in alcoholism. Most often the etiological factors have been operative for a month or more. Acute hypo‐magnesemia can occur without previous Mg deficiency after epinephrine, cold stress and stress of serious injury or extensive surgery. The clinical manifestations depend on the age of the patient and may begin insidiously or with dramatic suddenness, or there may be no overt symptoms or signs. The manifestations can be divided into the following categories: totally non‐specific symptoms and signs ascribable to the primary disease; neuromuscular hyperactivity including tremor, myoclonic jerks, convulsions, Chvostek sign, Trousseau sign (rarely), spontaneous carpopedal spasm (rarely), ataxia, nystagmus and dysphagia; psychiatric disturbances from apathy and coma to some or all facets of delirium; cardiac arrhythmias including ventricular fibrillation and sudden death; hypocalcemia which is responsive only to Mg therapy; and hypokalemia which is not easily nor completely corrected without Mg therapy. The diversity of etiologies and the multiplicity of manifestations result in confusion and controversy. The documentation of normal renal function is absolutely necessary for maximum doses. The order of magnitude of dose is 1.0 meq Mg/kg on day 1, and 0.3 to 0.5 mEq/kg per day for 3 to 5 days. In emergencies such as convulsions or ventricular arrhythmias, a bolus injection of 1.0 gm (8.1 meq) of MgSO4 is indicated. Therapy of Mg deficiency in the presence of renal insufficiency requires smaller doses and frequent monitoring. Complete repletion occurs slowly.

Proton-pump inhibitor use is associated with low serum magnesium concentrations

“…The classic symptoms of severe hypomagnesemia include tetany, convulsions, bradycardia, hypotension, and death. 22–24 Even mild hypomagnesemia may be clinically important and has been associated with cardiovascular and total mortality, 25 possibly through effects on left ventricular size, 26,27 hypertension, 28,29 endothelial function, 30 and insulin resistance. 31 …”

Trousseau sign in hypocalcemia

“…2 Trousseau sign is more specific than Chvostek sign for latent tetany, which can be caused by hypocalcemia, hypomagnesemia and metabolic alkalosis. 3,4 A positive Trousseau sign is seen in 1%-4% of healthy people. 1 The sensitivity of the sign is not known, but the sign can be absent in patients with definite hypocalcemia.…”

Transplant Recipients on the Edge of the Hypocalcemia Abyss

“…Hypocalcemia has been reported to respond to magnesium supplement in patients with normomagnesemic magnesium depletion. 10 Magnesium level should therefore be checked in all hypocalcemic patients, and magnesium supplementation may be considered in resistant cases even if serum magnesium concentration is normal.…”