Clin Rheumatol. 2026 Feb 17. doi: 10.1007/s10067-026-07966-7. Online ahead of print.
ABSTRACT
OBJECTIVES: To evaluate serum tartrate-resistant acid phosphatase 5b (TRACP5b) levels in patients with ankylosing spondylitis (AS) and primary osteoporosis (OP), and to assess its diagnostic value, correlations with bone mineral density (BMD) and disease activity, and its potential as a marker of secondary osteoporosis in AS.
METHODS: In this cross-sectional comparative study, 23 patients with AS, 24 patients with primary OP, and 20 healthy controls were recruited from Assiut University Hospitals. Demographic, clinical, laboratory, and dual-energy X-ray absorptiometry (DXA) data were collected. AS disease activity was assessed using Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). Serum TRACP5b was measured by ELIZA. Group differences, correlations, and ROC curve analysis were performed.
RESULTS: AS patients were predominantly male and younger than OP patients. Primary OP patients had significantly lower DXA T-scores than AS patients (mean difference = 2.36, p < 0.001). TRACP5b levels were higher in AS patients than controls but not significantly different (p = 0.111). In AS, TRACP5b correlated with age (r = 0.534, p = 0.009) and disease activity (r = 0.427, p = 0.042) but not with BMD. ROC analysis showed moderate diagnostic performance for detecting secondary osteoporosis in AS (AUC = 0.653). No significant differences in TRACP5b or BMD were found across AS treatment groups.
CONCLUSION: Serum TRACP5b may serve as a supplementary marker of osteoclast activity in AS and shows moderate diagnostic value for secondary osteoporosis, with levels more related to age and disease activity than BMD. Larger studies are needed to confirm its clinical utility. Key Points • Serum TRACP5b levels were higher in patients with AS than in healthy controls, though without consistent statistical significance, reflecting biological variability. • TRACP5b correlated positively with age and disease activity (BASDAI) in AS but not with BMD, disease duration, or ESR, highlighting its link to inflammatory bone resorption. • ROC analysis showed TRACP5b had moderate diagnostic performance for secondary osteoporosis in AS, but limited value in primary osteoporosis. • Our findings suggest that TRACP5b may serve as supplementary marker of bone turnover in AS, warranting further validation in larger, longitudinal studies.
PMID:41699179 | DOI:10.1007/s10067-026-07966-7
