High Serum Alpha-2-Macroglobulin Level in Patients with Osteonecrosis of the Femoral Head

  Background: Diagnosis of osteonecrosis of the femoral head (ONFH) is complicated due to the lack of reliable serum biomarkers. Up-regulation of alpha-2-macroglobulin (A2M) gene has been reported in glucocorticoid-induced ANFH rat model. This study aimed to investigate whether the serum level of alpha-2-macroglobulin (A2M) can be used for ONFH diagnosis. Methods: Serum protein capillary electrophoresis was performed on the sera of 36 ONFH patients. Also, human enzyme-linked immunosorbent assay was performed to evaluate the serum levels of A2M. Results: Alpha-2 subunit level, composed of alpha-2-macroglobulin, ceruloplasmin and 2-2 haptoglobin phenotype, was increased significantly as compared to healthy subjects (P=0.0001). Moreover, ELISA assay confirmed significant elevation in the A2M (P=0.037). Conclusion: Our findings suggest that avascular necrotic femur head presumably directly or indirectly elevates A2M in the bloodstream. Thus, serum level of A2M might be used as a reliable diagnostic tool in clinical practice. Level of evidence: II