Development of an in house ELISA for human intact osteocalcin and its utility in diagnosis and management of osteoporosis

Abstract

BackgroundSerum Osteocalcin (OC) is a biomarker for evaluating bone turnover in humans. Commercial kits of OC in India are imported, hence the associated high cost prohibits their use in routine screening of osteoporosis. The present study describes the development, validation of human OC ELISA and establishes cut off values for its use in screening and management of women at risk for osteoporosis. MethodsA sandwich OC ELISA was developed using immuno-reagents prepared indigenously and validated for analytical sensitivity, specificity, accuracy and compared with commercial kit using Bland-Altman method. The utility of OC assay was evaluated by ROC analysis. ResultsThe new ELISA was sufficiently precise, accurate, matrix-free, sensitive and cost effective. The levels of OC were significantly different in women with osteopenia and osteoporosis (ANOVA, p < .0001) compared to women with normal BMD. ROC analysis demonstrated the cut off values of OC >11.9 ng/mL for osteopenia and > 14.9 ng/mL for osteoporosis. The OC levels had maximum AUC of 0.831 in osteopenia and 0.932 in osteoporosis. Further, OC levels showed significant changes within 3 months in women monitored on therapy. ConclusionThe developed OC ELISA has great potential to be used as a biomarker for routine screening and management of osteoporosis in Indian women.