Hypocalcaemia: Causes, diagnostics and treatment

Hypocalcaemia is a state with total calcium serum level below 2.25 mM/l. From the total serum calcium content, 50% is free and ionized, 40% is protein-bound and 10% is bound for organic anions. The most frequent causes of hypocalcaemia are iatrogenic hypoparathyroidism, magnesium deficit, disorders of vitamin D metabolism and chronic renal failure. Iatrogenic hypoparathyroidism is associated with low serum ionized calcium and low serum parathormone levels. There are two important clinical signs of hypocalcemia: Chvostek’s sign (twitches of upper lip after percussion on facial nerve over mandible) and Trousseau’s sign (carpal spasm after increasing pressure in blood pressure cuff placed about the upper arm for 20 milimeters above systolic pressure for 3-5 minutes). The following lab analyses should be performed when hypocalcaemia is an option: serum levels of calcium, magnesium, 25 – hydroxyvitamin, parathormone, potassium, sodium, chloride and bicarbonates. If hypocalcaemia is mild, it could be treated with oral calcium preparations, usually calcium carbonate, in a dose of 1 to 2 grams of elemental calcium daily. In more severe hypocalcaemia intravenous calcium-gluconate or calcium-chloride should be administered, as 10% solutions. These parenteral preparations of calcium should be diluted prior to the intravenous administration, and the administration should be longer than 20 minutes in order to avoid adverse effects on heart. If administration of calcium does not correct hypocalcaemia, oral vitamin D should be also prescribed. If this does not regulate calcaemia, from 0.25 tо 1 micrograms of 1,25-dihydroxyvitamin D (clacitriol) daily should be prescribed. Calcium serum levels should be kept within the lower part of normal serum concentration range.