Background: Tartrate-resistant acid phosphatase isoform 5b (TRACP5b) is a serum bone resorption marker. Our aim was to investigate its utility in monitoring metabolic bone disease.
Methods: Serum TRACP5b, C-terminal cross-linking telopeptide of type I collagen, urine N-terminal cross-linking telopeptide of type I collagen and free deoxypyridinoline were measured pre- and post-treatment with a parathyroid hormone analogue [PTH (1-34)] (n = 14) or a bisphosphonate (N-BP) (n = 8). TRACP5b, bone alkaline phosphatase (bone ALP), 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) were measured in 100 osteoporosis patients on prolonged bisphosphonate therapy.
Results: Changes in TRACP5b were smaller in magnitude but mimicked those of other bone resorption markers. Absolute changes in TRACP5b and the other resorption markers correlated significantly (p < 0.001). In patients on long-term bisphosphonates, TRACP5b and bone ALP levels were not suppressed. Vitamin D status was consistent with the level of supplementation.
Conclusion: TRACP5b has limited utility as a single marker of metabolic bone disease treatment.