Intermittent intravenous followed by intermittent oral 1α(OH)D3 treatment of secondary hyperparathyroidism in uraemia

Abstract

To examine whether intermittent oral 1 alpha(OH)D3 treatment of patients on haemodialysis with secondary hyperparathyroidism (HPT) was able to maintain the marked suppression of PTH, which previously had been induced by an intermittent intravenous administration of 1 alpha(OH)D3. Simultaneously, the effect of the different routes of administration of 1 alpha(OH)D3 on the circulating levels of N- and C-terminal PTH fragments was measured. An open study of patients on chronic haemodialysis. Renal division, Rigshospitalet, Copenhagen, Denmark. A total of 26 patients started and five patients completed the total protocol. The treatment protocol was divided into three parts: (i) 1 alpha(OH)D3 administered intravenously for > 300 days; then (ii) 1 alpha(OH)D3 administered orally for 100 days, followed by (iii) 1 alpha(OH)D3 administered intravenously again for another 100 days. 1 alpha(OH)D3 was given three times a week at the end of each dialysis. Intact PTH, N- and C-terminal PTH. Intact PTH levels were significantly (P < 0.0001) suppressed by 90.4 +/- 3.3% after 56 days of intermittent intravenous 1 alpha(OH)D3 treatment. This degree of suppression remained stable during the following period of oral treatment and did not change further when intravenous treatment was reinstituted. The circulating levels of intact PTH and N- and C-terminal iPTH were not influenced by the administered route of 1 alpha(OH)D3. Intravenous 1 alpha(OH)D3 treatment of the secondary HPT in dialysis patients can safely be changed to oral treatment at the time when optimal suppression of PTH has been achieved.