Effect of 1alpha-hydroxyvitamin D3 on parathyroid function in patients with chronic renal failure

The effect of 1alpha-hydroxyvitamin D3 (1alpha-OHD3) on parathyroid function was studied in sixteen patients (ten on haemodialysis, six with chronic renal insufficiency) during treatment for 6--8 months. During treatment, a decrease in serum parathyroid hormone (s-PTH) and an increase in serum calcium were seen. An inverse linear correlation was found between serum calcium and logarithmic values of s-PTH in fifteen of sixteen patients, but the slopes of the regression lines varied considerably. This indicates that the suppression of parathyroid function seen during treatment with 1alpha-OHD3 is mediated by a rise in the serum concentration of calcium. For normalization of s-PTH, the serum concentration of calcium had to be above normal range in several patients, indicating a defect in calcium-mediated regulation of the secretion of parathyroid hormone. This abnormality was seen especially in long-term haemodialysed patients.