Magnesium
is primarily an intracellular cation (second most abundant, 60% found in
bone). In extracellular fluid, it influences neuromuscular response and
irritability. A magnesium deficit may exist with little or no change apparent
in serum level.
Normal
Range: 1.8-3 mg/dL
increased
in: Dehydration, tissue trauma, renal failure; hypoadrenocorticism; hypothyroidism.
Drugs: aspirin (prolonged use), lithium, magnesium salts, progesterone,
triamterene, vitamin D (renal failure).
Decreased in: Chronic
diarrhea, enteric fistula, starvation, chronic alcoholism, chronic liver
disease, total parenteral nutrition with inadequate replacement, hypoparathyroidism
(especially post-parathyroid surgery), high-dose vitamin D and calcium
therapy, acute pancreatitis, delirium tremens, chronic glomerulonephritis,
hyperaldosteronism, diabetic ketoacidosis, SIADH, pregnancy. Drugs: albuterol,
amphotericin B, calcium salts, cisplatin, citrates (blood transfusion),
cyclosporine, diuretics, ethacrynic acid.
Additional: Mg2+
concentration is determinated by intestinal absorption, renal excretion,
and exchange with bone and with intracellular fluid.
