Osteocalcin Levels in Uremic Patients: Influence of Calcitriol Treatment through Two Different Routes and Type of Dialysis

Abstract

Osteocalcin, the most abundant non-collagen protein of bone, is synthesized by the osteoblast. Serum osteocalcin concentration depends primarily on new cellular synthesis, and is a sensitive marker of bone turnover reflecting osteoblastic function. In uremic and hemodialysis (HD) patients, a direct relationship between serum osteocalcin and histological parameters of bone formation has been observed. The modality of dialysis may influence serum osteocalcin levels though the available data are controversial. The aim of this study is to assess the acute and chronic effects of calcitriol and the influence of modality of dialysis on serum osteocalcin levels. Twelve patients on continuous ambulatory peritoneal dialysis (CAPD) were treated with calcitriol. For control purposes, 24 patients, 12 on CAPD and 12 on HD, not treated with calcitriol serum osteocalcin levels were included. In CAPD patients previously treated with calcitriol, serum osteocalcin levels were higher than in nontreated patients. The higher levels occur independent of serum levels of parathyroid hormone (PTH), Ca and P. Hemodialysis patients had osteocalcin levels similar to those of CAPD patients under calcitriol treatment. However, the levels of HD patients were higher than CAPD nontreated patients. Serum ionized Ca was similar in CAPD and HD nontreated patients; however, total Ca was significantly higher in HD than in CAPD patients, both with and without calcitriol. After the intravenous administration of calcitriol, serum osteocalcin levels increased from 9.2 + 2.5 to 13.5 + 5.4 ng/ml (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)