Normal plasma magnesium concentration ranges from 0.70 - 1.05 mmol/L. Only about 1% total body magnesium is found in extracellular fluid; the remainder is in bone and soft tissue. About 25% of plasma magnesium is bound to albumin so high or low albumin concentrations will affect magnesium levels.
Hypomagnesaemia almost always indicates magnesium deficiency. Hypomagnesaemia may arise through inadequate absorption, by excessive urinary losses or by redistribution of magnesium from extracellular to intracellular. It also might due to decreased renal tubular reabsorption, drugs, pregnancy and lactation and endocrine disorders and hyperthyroidism.
Hypomagnesaemia is diagnosed by a serum Mg level less than 0.70 mmol/K. Severe hypomagnesaemia usually results in levels of less than 0.50 mmol/L. As magnesium is involved in an array of structural and physiological functions, adverse effects associated with hypomagnesemia may occur in almost every organ system, whether they are clinically acute and overt, or chronic and subtle.
Symptoms of hypomagnesaemia are diverse and include muscle cramps, extra heart beats and neuromuscular irritability associated with convulsions in very severe cases.
Symptoms directly attributable to hypomagnesaemia occur at plasma concentrations below 0.5 mmol /L includes anorexia, nausea, tremor, apathy, depression, agitation and confusion.
Hypocalcaemia, due to increased PTH secretion is a clinically important consequence of hypomagnesaemia. Hypophosphataemia and hypokalaemia may also be present, not all abnormalities usually respond to magnesium supplementation.
Hypomagnesaemia: Common causes and manifestation
Hypomagnesaemia: Common causes and manifestation
