Correction of low circulating levels of 1,25-dihydroxyvitamin D by 25-hydroxyvitamin D during reversal of hypomagnesaemia.

The effect of 25-hydroxyvitamin D (25OHD), given orally during the reversal of hypomagnesaemia, was studied in five patients with hypomagnesaemic hypocalcaemia and low serum levels of 25OHD and 1,25-dihydroxyvitamin D (1,25(OH)2D). The results were compared to those obtained in five other patients with similar initial levels of magnesium, calcium, 25OHD and 1,25(OH)2D who did not receive 25OHD. Serum levels of 1,25(OH)2D in the ten hypomagnesaemic patients were lower than in ten control subjects with low serum levels of 25OHD.

Are tuberculous patients at a great risk from hypercalcemia?

The risk of tuberculous patients to develop hypercalcemia was investigated in 33 patients aged 19 to 80. Twenty-two of the 33 received no vitamin D supplements. Before antituberculous chemotherapy serum calcium corrected for albumin and urinary calcium levels were normal, serum 25-hydroxyvitamin D (25(OH)D) levels were low, but serum 1,25(OH)2D levels, oral calcium load test and intestinal 47Ca absorption were normal.

Magnesium administration reverses the hypocalcaemia secondary to hypomagnesaemia despite low circulating levels of 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D.

The effect of parenteral administration of magnesium was studied in five patients with hypomagnesaemic hypocalcaemia. The initial metabolic state was characterized by a normal level of serum immunoreactive parathyroid hormone (iPTH), and by low or undetectable serum 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25 (OH)2D). A parathyroid response was elicited by the acute intravenous injection of magnesium chloride.