[Long-term treatment with large doses of alphacalicidol in secondary hyperparathyroidism of patients dialyzed for end stage renal failure].

The purpose of the study was to evaluate the effectiveness of the long-term oral pulse therapy with high doses of alphacalcidol (1 alpha (OH)D3) in severe uremic hyperparathyroidism. 43 hemodialysis patients with at least 5-fold 1-84 PTH serum elevation were given thrice a week oral (1 alpha (OH) D3) in doses up to 5 micrograms, according to serum calcium levels (monitored weekly). The drug was given in the evenings (Group A; 18 pts) or during hemodialysis sessions (Group B; 25 pts). The dialysate calcium was reduce to 1.40-1.45 mmol/l and CaCO3 was used as a main phosphate binder in doses up to 6 g/day; 13 pts received additionally small doses of Al (OH)3 (up to 3 g/day). After one month the PTH levels decreased by 67 +/- 7.7% (p < 0.001), while serum total calcium increased by 0.27 < or = 0.05 mmol/l. The parathyroid activity suppression progressed to 81 +/- 6.9% serum PTH reduction after 4 months and 74 +/- 6.1% fall after 8 months. Only 3 pts occurred to be non-responders; in 19 pts PTH levels normalized. A decrease of serum hydroxyproline and alkaline phosphatase with its bone isoenzyme activity was also observed with a direct correlation between those changes and parathyroid suppression. (1 alpha (OH) D3) dose at first month of therapy was 3.4 +/- 0.15 micrograms, but it was successively reduced because of hypercalcemia to a final dose of 2.2 +/- 0.22 micrograms. The frequency of hyperkalcemia was 7.6%; no difference between Group A and group B was noted. We conclude that oral (1 alpha (OH)D3) pulse therapy is very effective in the long-term parathyroid activity suppression in hemodialysis patients with severe hyperparathyroidism. To avoid dangerous hypercalcemia and relative hypoparathyroidism serum PTH and calcium levels should be carefully monitored.