Current advances in the therapy of secondary hyperparathyroidism and osteitis fibrosa.

Secondary hyperparathyroidism is commonly observed in dialysic patients. Recent observations demonstrate a direct inhibitory effect of calcitriol on parathyroid hormone (PTH) synthesis and secretion. These observations may have important clinical and therapeutical implications. Thus, several studies have shown that intravenous calcitriol, in dialysis patients with severe secondary hyperparathyroidism, has a direct inhibitory effect on PTH levels. Furthermore, the sigmoidal PTH-calcium relationship is shifted toward a more normal range after intravenous calcitriol. In addition, the use of calcitriol early during the course of renal failure prior to dialysis has demonstrated therapeutic benefits. Thus, both early therapy with oral calcitriol and later during maintenance dialysis, the addition of the intravenous form may provide various therapeutical alternatives which make surgical parathyroidectomy rarely necessary. Furthermore, the course of patients undergoing surgical parathyroidectomy is not benign.