Changes in Serum Levels of Cartilage Oligomeric Matrix Protein after Estrogen and Alendronate Therapy in Postmenopausal Women

<b><i>Background:</i></b> Cartilage oligomeric matrix protein (COMP) is a biomarker for joint destruction and its serum levels are used for assessing therapeutic efficacy. This study aims to compare changes in serum COMP levels in postmenopausal women with osteopenia/osteoporosis receiving estrogen and alendronate. <b><i>Methods:</i></b> A total of 62 postmenopausal women diagnosed with osteopenia or osteoporosis were treated with either estrogen (17β-estradiol 1 mg, n = 30) or bisphosphonate (alendronate 5 mg, n = 32) for 6 months. The controls were healthy postmenopausal women (n = 30). Serum COMP and osteocalcin levels were measured at baseline and after 6 months of treatment. <b><i>Results:</i></b> Estrogen decreased levels of COMP at 6 months compared to baseline levels (–8.35 ± 19.38%), whereas the bisphosphonate and control groups resulted in no significant changes (–5.50 ± 18.69 and –1.49 ± 25.34%, respectively). Concentrations of osteocalcin decreased significantly in both treatment groups (estrogen –25.60 ± 24.42% and alendronate –13.76 ± 23.89%, respectively). There was a significant positive correlation between changes after 6 months in COMP and osteocalcin (R = 0.48, p = 0.002). <b><i>Conclusions:</i></b> Postmenopausal women treated with estrogen showed significantly decreased levels of COMP after 6 months. Estrogen might provide a further treatment modality in the prevention of joint destruction.