Hypomagnesaemia: Common causes and manifestation

Magnesium is essential for a number of intracellular functions and low levels may potentially be life-threatening. It is also an essential constituent of many enzyme systems, particularly those involved in energy generation.

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

Magnesium Deficiency

Magnesium Deficiency
Magnesium deficiency may occur in man as a result of prolonged episodes of vomiting or malabsorption as in severe diarrhea.

Gastric juice contains a fair amount of magnesium and excessive vomiting could result in substantial losses of the mineral in addition to the loss resulting from the failure to retain ingested food.

Certain drugs – ammonium chloride and mercurial diuretics – result in loss of magnesium through the urine.

Magnesium deficiency has been reported in children with protein-calorie malnutrition due to primarily to diarrhea which increases fecal loss of the mineral.

Recovery was more prompt when diets were supplements with magnesium.

Hypomagnesaemia is associated with chronic alcoholism and with the neuromuscular symptoms of alcoholic withdrawal.

When pancreatitis is also present, magnesium replacement therapy becomes an important part of treatment because magnesium (and calcium) in blood may be decreased due to presumably to deposition in areas of adipose tissue.

Magnesium content of adipose tissue has been shown to be markedly increased in humans dying from acute pancreatitis and in animals in whom pancreatitis was induce experimentally.

Cellular loss of magnesium may be a primarily biochemical mechanism in the etiology of various types of myocardial lesions.

The high content of magnesium in hard water cited as a possible reason for the lower incidence of sudden death from heart disease in areas of hard water as compared to soft water areas.
Magnesium Deficiency