Useful biochemical markers for the identification of bone turnover and the evaluation of ICTP as a new bone resorptive marker in hemodialysis patients

ABSTRACT

Chronic renal failure is often associated with several bone disorders. In this study, the serum levels of iPTH and a panel of bone formation and resorption markers with a new applied resorptive marker, ICTP, the carboxyterminal telopeptide region of type I collagen, were evaluated in chronic renal failure patients undergoing hemodialysis. A group of 83 patients was divided into 2 subgroups according to serum iPTH levels. The two categories were iPTH less than 100pg/mL [42 patients, mean age 51.9 +/- 12.3 years, 19males, 23females], and iPTH levels above 200pg/mL [41 patients, mean age 47.34 +/- 16.95 years, 22 males, 19females].In addition, a group of 50 healthy subjects [28 males, 22 females, average age 45.78 +/- 9.9years] was chosen as a control group. Calcium phosphorus, urea, creatinine, and tALP were measured. Intact parathyroid hormone [iPTH], N-Mid Osteocalcin [OC] and BETA-Crosslaps [BETA-CTX], and ICTP were assayed. In both groups of patients, it was found that levels of all bone turnover markers were elevated above normal range compared to the control group. Significant variations were found between the two categories in all biochemical markers [P<0.05], except creatinine, which did not differ significantly between the two subgroups [P=0.17]. The ICTP showed a significant positive correlation with the time on dialysis, iPTH, t-ALP, BETA-CTX and a significant negative correlation with N-Mid OC in both subsets. The results indicate that chronic renal failure patients undergoing hemodialysis may have high-turnover bone disease due to secondary hyperparathyroidism or low-turnover bone disease because of hyperparathyroidism which predisposes to bone loss. The elevated perls of the formation and resorptive markers studied strongly suggest disturbed bone remodeling cycles in addition to malfunction of the osteoblasts and osteoclasts. The ICTP and BETA-CTX markers may be important for studying bone resorption in hemodialysis patients