High dose pulse iv or oral 1,25 (OH)2,D3,/1(αOH)D3, therapy in uremic hyperparathyroidism has been shown to be much more effective than daily standard doses. The problem of hypercalcemia, however, still exists. Since in the last years protracted fall in serum PTH was found after a single dose of 1,25 (OH)2,D3, we decided to check whether 1(αOH)D3, administrated once weekly is effective in parathyroid hyperactivity of chronic renal failure. 17 hemodialysis patients with advanced hyperparathyroidism were given oral alphacalcidol in doses of 6 (g once a week, during the dialysis session. Dialysate calcium was 1.40 - 1.45 moll/l, and CaCO3, (up to 6 g/day) was used as the main phosphate binder; in 6 patients Al(OH)3, (up to 3 g/day) was added. The doses of 1 (αOH)D3,CaCO3, and Al(OH)3, were modified according to the calcium and phosphate levels. Serum 1 - 84 PTH decreased significantly after 2 weeks (p (0.02), and then the reduction of parathyroid activity progressed to 51&plusm;6.1% at the end of the study. The normalisation of PTH secretion was seen only in one patient and the treatment was ineffective in 4 patients; 3 of them had initial serum PTH levels (800 pg/ml. The serum 1,25 (OH)2,D3, levels increased from 8.5±1.08 pg/ml to 17.0±2.72 pg/ml (p<0.025). Serum total calcium, phosphate, alkaline phosphatase activity and hydroxyproline levels did not change significantly, nor did the doses of 1α(OH)D3,CaCO3, and Al(OH)3,. The incidence of hypercalcemia was 2.6% hese results indicate that oral pulse therapy with alphacalcidol administered once a week effectively reduces PTH secretion in hemodialysis patients with moderate hyperparathyroidism, with low risk of hypercalcemia and oversuppression of parathyroid activity.

Keywords: alphacalcidol, chronic renal failure, uremic hyperparathyroidism, hemodialysis