Bone markers in metabolic bone disorder in patients on chronic hemodialysis and kidney transplant recipients

• Published in: Biochemia medica Vol. 16; no. 2; pp. 137 - 149
• Main Authors: Zupanic, Danijela, Vlasic-Tanaskovic, Jelena, Smalcelj, Ruzica, Kes, Petra, Kusec, Vesna
• Format: Journal Article
• Language: English
• Published: 2006
• ISSN: 1846-7482; 1330-0962; 1846-7482
• DOI: 10.11613/BM.2006.013

Background: Chronic kidney failure treated by chronic dialysis and kidney transplantation is characterised by disorder of bone metabolism and high or low bone turnover, resulting in osteopenia/osteoporosis and increased fracture risk. Measurement of bone markers enables indirect insight into the rate of bone remodeling and its changes in the course of disease. In this study bone formation and bone resorption markers were measured in patients on chronic hemodialysis treatment and in kidney transplant recipients with regard to specific risk factors of this metabolic bone disorder, i.e. parathyroid hormone levels (PTH), age, sex, hemodialysis duration and post-transplant period. Materials and methods: Blood samples were obtained from 79 patients (50 men, 29 women) on chronic hemodialysis and 36 patients (20 men, 16 women) with kidney transplant for measurement of bone alkaline phosphatase (BALP) as a bone formation marker, C-terminal telopeptide of collagen type I (crosslaps) as a bone resorption marker and intact PTH by commercial kits. Data on age, duration of hemodialysis and post-transplant period were included as risk factors for bone disorder. Results: Patients on chronic hemodialysis had significantly higher crosslaps (1.85 ug/L, p<0.0005) and PTH (21.99 pmol/L, p<0,001), and lower BALP (18.27 IU/L, p<0.0005) in comparison to kidney transplant recipients (crosslaps 1.18 ug/L, PTH 634 pmol/L, BALP 45.78 IU/L). In both patient groups hemodialysis duration correlated significantly and positively with BALP (hemodialysis patients r=0.318, p=0.005, kidney transplat recipients r=0.488, p=0.003) and crosslaps (hemodialysis patients r=0338, p=0.002, kidney transplant recipients r=0.365, p=0.03), and in hemodialysis patients with PTH (r=0.255, p=0.03). A statistically significant and positive correlation existed for both patient groups between PTH and BALP (hemodialysis patients r=0.522, p=0.0005, kidney transplant recipients r=0.456, p=0.02), BALP and crosslaps (hemodialysis patients r=0.459, p=0.0005, kidney transplant recipients r=0.593, p=0.0005), and in hemodialysis patients also between PTH and crosslaps (r=0.323, p=0.004). In kidney transplant recipients crosslaps correlated negatively with post-transplant period (r=-0.479, p=0.004). Patients on chronic hemodialysis were significantly older (61 years, p=0.0005) and were significantly longer treated by hemodialysis (79 months, p=0.04) as compared to the kidney transplant recipients (age 46 years, dialysis treatment 55 months). No difference in data existed between sexes in both patient groups. Conclusions: Bone turnover was increased in both patient groups, in particular bone resorption. Duration of hemodialysis and PTH were recognised as determinants of increased bone turnover in both groups, and normalization of bone resorption was related to post-transplantation period. In this bone disorder sex and age were not established as risk factors for impaired bone turnover. Measurement of bone markers together with PTH is a useful clinical tool in assessment and follow-up of metabolic bone disorders of chronic hemodialysis treatment and kidney transplantation.