The significance of serum C-telopeptide as a bone marker in chronic hemodialysis patients

Lee, Chang Sook; Yoon, Sung Chul

Abstract

BACKGROUND/AIMS
Checking bone mineral density (BMD) is not sufficient for determining the progression of renal osteodystrophy. Measuring pyridinoline or deoxypyridinoline in urine does not give an accurate bone status, due to insufficient urine in patients with renal failure. However, another biochemical marker, beta-CTX (the carboxy-terminal telopeptide of type 1 collagen), in serum is believed to be a good indicator of the status of renal osteodystrophy.
METHODS
Fifty-nine patients undergoing hemodialysis agreed to have their blood and BMD checked. Beta-CTX was measured using an electro-chemiluminescence sandwich immunoassay and BMD was counted at the lumbar spine, femoral neck, and distal humerus using a Discovery-Wi (Hologic).
RESULTS
Bone-alkaline phosphatase (49.8+/-36.7 U/L), parathormone (PTH) (192.8+/-263.3 U/L), osteocalcin (33.4+/-18.2 ng/mL), and beta-CTX (2.1+/-1.2 ng/mL) were all increased, while the average BMD of the lumbar spine (0.86+/-0.17), femoral neck, (0.67+/-0.14) and distal humerus (0.67 +/- 0.17) were all decreased. The BMD of the femoral neck in females was significantly lower than in males (p=0.044). The serum phosphate and PTH concentrations in non-diabetics were significantly higher than in diabetics (p=0.001, p=0.04, respectively). The measured serum osteocalcin and beta-CTX concentrations in patients older than 40 years were much lower than in patients younger than 40 (p=0.009, p=0.01, respectively). Beta-CTX was strongly correlated with bone-alkaline phosphatase (r=0.625, p=0.00), osteocalcin (r=0.698, p=0.00), and PTH (r=0.648, p=0.00).
CONCLUSIONS
Beta-CTX is another convenient, significant marker for evaluating renal osteodystrophy.