[Oral calcitriol pulse therapy in hemodialysis patients. Effects on histomorphometry of bone in renal hyperparathyroidism].

Background: Hemodialysis patients with symptomatic renal hyperparathyroidism should only get a surgical parathyroidectomy if the oral calcitriol pulse therapy fails. Unfortunately there is no general accepted recommendation for the dosage and intervals of the oral calcitriol pulse therapy.

Patients And Methods: In 34 hemodialysis patients (9 women, 25 men, mean age: 50 +/- 13 years, mean duration time of dialysis: 20 +/- 30 months) with renal hyperparathyroidism (intact parathormon = iPTH > 20 pmol/l) an oral calcitriol pulse therapy was performed over a period of one year. The initial dosage of calcitriol was 0.1 microgram/kg bwt a week, splitted into two equal dosages given at night. After 3 months the calcitriol dosage was changed according to the iPTH, calcium and phosphate levels. The dialysate calcium concentration was kept constant with 1.5 mmol/l. Before and after one year a bone biopsy was performed. The target level for a successful treatment was < or = 20 pmol/l.

Results: In the group of responders (n = 24) the iPTH level decreased significantly (p < 0.01) from 37.5 +/- 3.2 to 14.3 +/- 1.9 pmol/l after a period of 12 months. There was no significant change of the iPTH levels in the 10 non-responders (55.5 +/- 6.5 vs 57.2 +/- 9.7 pmol/l). The incidence of hypercalcemia was higher in the non-responder group (19.2%) as compared to the responder group (13.4%). In the group of responders the bone resorption decreased, whereas the bone formation increased under an oral calcitriol pulse therapy.

Conclusion: A decrease in iPTH level in hemodialysis patients undergoing an oral calcitriol pulse therapy with an initial dosage of 0.1 microgram/kg bwt. was found in 71% of the patients after one year. Calcitriol improves the histomorphometrical parameters in responders.