Low serum osteoprotegerin levels in premenopausal infertile women with low bone density: an association of relevance?

Abstract

To evaluate if the levels of the central regulators of osteoclast activity, osteoprotegerin (OPG) and receptor activator for nuclear factor kappaB-ligand (RANk-L), correlate with bone mineral density (BMD) parameters in premenopausal infertile women. Cross-sectional study. Academic infertility practice. 82 Infertile, but otherwise healthy, premenopausal women< 42 years age presenting for routine care. BMD assessment; serum samples (cycle days 1 to 3), questionnaire addressing demographics, medical, social, family, and personal histories. BMD categorized as "Low" (Z <or= -1.0) or "Normal" (Z > -1.0); Biomarkers of bone metabolism (BAP, TRAP, NTX, OPG, RANK-L) and ovarian reserve (FSH, estradiol). The prevalence of low BMD was 23% (19/82). Significantly lower levels of OPG were observed in association with low BMD compared with normal BMD (1.37 +/- 0.57 versus 2.0 +/- 1.05 pMol/L). Multivariable logistic regression analyses revealed low OPG levels as independent predictors of low BMD after adjusting for parameters known to influence bone density. We demonstrate an independent relationship between low circulating levels of OPG and low BMD in premenopausal healthy, albeit infertile, women.