Serum TRACP-5b as a Marker for Bone Turnover in Chronic Kidney Disease: Correlation with Mineral-Bone Disorder Markers

Background: Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) leads to progressive alterations in bone turnover and mineral metabolism. Tartrate-resistant acid phosphatase 5b (TRACP-5b) is a promising biomarker for bone resorption, potentially independent of renal function. Primary Objectives: To evaluate the diagnostic efficacy of serum TRACP-5b in predicting bone turnover abnormalities in patients with chronic kidney disease (CKD). Secondary Objectives: To assess the correlation of serum TRACP-5b with established biochemical markers of CKD–Mineral and Bone Disorder (CKD-MBD), including bALP, PTH, calcium, and phosphorus. Methods: This case-control observational study included 100 CKD patients (stages II–V) and 100 age- and sex-matched healthy controls. Serum TRACP-5b, bone alkaline phosphatase (bALP), parathyroid hormone (PTH), calcium, and phosphorus were analysed. Receiver Operating Characteristic (ROC) analysis assessed diagnostic performance, and Pearson’s correlation evaluated biochemical relationships. Results: TRACP-5b levels increased progressively with CKD severity (Stage II: 3.1±0.62 U/L; Stage V: 7.4±1.1 U/L; Controls: 2.1±0.57 U/L, p<0.01). TRACP- 5b exhibited strong correlation with bALP (r=0.718, p<0.01) and moderate correlation with phosphorus (r=0.441, p<0.01) and PTH (r=0.496, p<0.01). ROC analysis demonstrated superior diagnostic accuracy for TRACP-5b (AUC=0.948) and bALP (AUC=0.981) compared to PTH and phosphorus. Conclusion: TRACP-5b is a reliable biomarker for bone turnover abnormalities in CKD patients and remains unaffected by declining renal function, supporting its potential clinical utility.