SERUM PARATHYROID-HORMONE SUPPRESSION BY INTRAVENOUS 1,25-DIHYDROXYVITAMIN D-3 IN PATIENTS ON MAINTENANCE HEMODIALYSIS

Secondary hyperparathyroidism in patients with end-stage renal disease is characterised by elevated circulating levels of parathyroid hormon e, due to inadequate synthesis of calcitriol, the active metabolite of vitamin D. Recent studies suggest that administration of calctriol ma y directly suppress parathyroid (PTH) secretion independent of changes in serum calcium. We have studied the effect of intravenous calcitrio l administration on the PTH level in 14 patients on maintenance haemod ialysis with serum PTH levels above 2,000 pmol/l over a 16-week period . There was a significant reduction in the PTH level (65%) and a rise of serum calcium to the normal range. There was a significant reductio n in serum PTH levels before the serum calcium concentrations increase d, suggesting that calcitriol directly inhibits PTH release. In conclu sion, intravenous treatment with calcitriol is of clinical importance, because it suppresses hypersecretion of PTH in uraemic patients, with minimal side effects.