Histomorphometric changes in trabecular bone of renal failure patients treated with calcifediol

Patients with chronic renal failure on long-term hemodialysis with clinical and/or radiological evidence of bone disease received calciferdiol three times weekly for 17 weeks (21 patients) or 86 weeks (15 patients). Transilial bone biopsies were performed with double tetracycline labeling before and after treatment. The trabecular bone was subjected to quantitative histomorphometric analysis. Two groups of patients were identified on the basis of their control histological parameters. One group of patients (active bone) showed disease characterized primarily by bone manifestations of secondary hyperparathyroidism. The bone was characterized by excessive osteociastic resorption and an increased rate of bone formation. A second group (inactive bone) showed no histological evidence of secondary hyperparathyroidism, but exhibited a derangement of mineralization characterized by lower mineral appositional rates and markedly decreased bone formation rates. All patients showed an excess in the volume and extent of unmineralized osteoid. Calcifediol treatment resulted in a decrease in osteoid volume and thickness in both groups. In patients with inactive bone there was a significant reduction in the osteold surface. In those patients with active bone calcifediol treatment resulted in a decrease in the histological manifestations of hyperparathyroidism. The patients with inactive bone continued to show a low degree of activity even after calcifediol treatment. However, that osteoid which underwent mineralization did so in an essentially normal fashion. The mineral appositional rate increased and there was an increase In the bone formation rate.