Evaluation of Osteoclastic Bone Markers in Individuals with Sickle Cell Anaemia: A Cross-Sectional Study in Zaria

Background: Sickle cell anaemia (SCA) is a chronic haemoglobinopathy often complicated by bone pain and skeletal pathology. Despite the high burden of SCA in sub-Saharan Africa, the evaluation of bone turnover markers is rarely integrated into clinical care. This study assessed the levels and diagnostic utility of two osteoclastic bone resorption markers—tartrate-resistant acid phosphatase 5b (TRACP 5b) and urinary deoxypyridinoline-to-creatinine (uDPD/Cr) ratio—in adult SCApatients in Zaria, Nigeria. Methods: A cross-sectional study was conducted involving 180 participants: 60 SCA patients in vasoocclusive crisis (VOC), 60 SCApatients in steady state, and 60 healthy HbAAcontrols. Serum TRACP5b and uDPD/Cr were measured using ELISA. Biochemical parameters, including serum calcium and phosphate, were also evaluated. Receiver Operating Characteristic (ROC) analysis determined diagnostic cut-offs, sensitivity, specificity, and predictive values. Results: Osteoclastic activity was significantly elevated in SCA patients during VOC compared to steady state and controls. Median uDPD/Cr was highest in VOC patients (7.23 nmol/mmol) versus steady state (0.97 nmol/mmol) and controls (3.48 nmol/mmol; p 0.001). TRACP 5b was similarly elevated in VOC (36.84 ng/ml) and controls (40.19 ng/ml), but lower in steady state (21.64 ng/ml; p 0.001). ROC analysis showed good discrimination for VOC using TRACP 5b (AUC = 0.742) and uDPD/Cr (AUC = 0.752). At optimal cutoffs, TRACP 5b 25.41 ng/ml had 81.7% sensitivity and 66.7% specificity, while uDPD/Cr 1.23 nmol/mmol had 89.8% sensitivity and 51.7% specificity. Both showed excellent negative predictive values  (99%). Conclusion: TRACP 5b and uDPD/Cr are elevated during VOC and show strong potential as non-invasive biomarkers for ruling out acute bone resorption in SCA. Their high sensitivity and negative predictive values support their clinical utility in low-resource settings to aid diagnosis and guide bone health interventions in SCApatients.