Yamada S et al. (2008) Utility of serum tartrate-resistant acid phosphatase (TRACP5b) as a bone resorption marker in patients with chronic kidney disease: independence from renal dysfunction. Clin Endocrinol (Oxf) 69: 189–196

Renal osteodystrophy, resulting from chronic kidney disease, can be assessed by measurement of serum parathyroid hormone (PTH) or serum bone turnover markers. The latter approach is believed to be more precise than measurement of PTH because of interindividual variation in bone responsiveness to PTH. Yamada et al. evaluated the performance of serum tartrate-resistant acid phosphatase 5b (TRACP5b), a biochemical marker for bone resorption, in comparison with established markers in the assessment of bone turnover.

A total of 98 predialysis patients (mean age 65.9 years; 66 men) with chronic kidney disease (serum creatinine >132.74µmol/l) were enrolled in the study. The researchers measured serum concentrations of PTH, two bone formation markers (bone-specific alkaline phosphatase and intact osteocalcin) and two bone resorption markers (TRACP5b and N-terminal cross-linking telopeptide of type I collagen [NTX]). All markers of bone turnover and PTH showed a significant negative correlation with glomerular filtration rate, and the levels of TRAPC5b were found to be unaffected by renal dysfunction. Serum TRACP5b was a superior bone resorption marker to serum NTX, which accumulates in uremic serum when the glomerular filtration rate reduces and could, therefore, potentially overestimate bone turnover.

Yamada and colleagues suggest that, as TRACP5b is unaffected by renal dysfunction, this bone resorption marker could provide a more reliable measure of bone metabolism than the variable PTH.