Effect of calcium and 1,25 dihydroxyvitamin D on the level of parathyroid hormone in patients with secondary hyperparathyroidism due to chronic renal insufficiency.

Thirty-two patients with chronic renal insufficiency on the heamodialys were studied. Serum calcium significantly correlated with mPTH/iPTH ratio (p < 0.01). The rise in concentrations of calcium during calcium infusion significantly increased mPTH/iPTH ratio (p < 0.05). Concentrations of iPTH declined for more than 50% in 65% patients during calcium infusion. Secretion of PTH was not suppressed in two patients. Serum PTH values were lower in group of patients who received 1,25 dihydroxyvitamin D (p < 0.05). Serum calcium values were similar in these investigated groups. Suppression of PTH secretion with calcium rose in group of patients who received 1,25 dihydroxyvitamin D for two years. Suppression of PTH with calcium declined in two of three investigated patients who did not receive 1,25 dihydroxyvitamin D for two years.