Serum osteoprotegerin and bone mineral density in post-menopausal women with or without osteoporosis

Abstract

OBJECTIVE: To study the relationship between osteoprotegerin (OPG), receptor activator of nuclear factor-kappa B ligand (RANKL), bone turnover markers and bone mineral density (BMD) in Saudi post-menopausal women with and without osteoporosis. DESIGN: A prospective study. MATERIALS AND METHODS: A prospective study was conducted on randomly selected Saudi postmenopausal women (age > 50 years) with osteoporosis (n = 215), or with normal BMD values (n = 215). The serum concentrations of OPG, RANKL together with total-T, bioavailable testosterone (bio-T), D4-A, total-E2, bio-E2, and DHEAS were measured. Also SHBG were measured with biochemical bone turnover markers including (formation: sOC, sBAP, sPICP; and resorption: sCTX, uCTX, uNTX, uDPYR). BMD of the spine (L1-L4), hip and neck femur were determined using DXA and women were classified with osteoporosis according to the WHO criteria. RESULTS: Women with osteoporosis exhibited markedly lower BMD values at various skeletal sites examined as compared with that of the corresponding controls. Women with osteoporosis exhibited significant decreases in the serum levels of OPG with no changes in that of RANKL but with moderate increase in the RANKL/OPG ratio values. Serum OPG levels were markedly correlated with age (r = 0.181; P < 0.011); years since menopause (YSM) (r = 0.196; P < 0.001) and BMD [spine (L1-L4)-T score; r = 0.316; P < 0.001; hip-Tscore; r = 0.287, P < 0.001; neck femur-T score; r = 0.222; P < 0.001]. In age- and BMI-adjusted postmenopausal women, the BMD values of the spine (L1-L4) correlated positively with total-T, free-T, bio-T, total E2, bio-E2, DHEAS and SHBG. Using logistic regression analysis, correction for age, YSM, BMI and other confounders, OPG was found to be independently associated with osteoporosis (OR: 3.3; 1.7 – 6.6) in the postmenopausal women examined. CONCLUSIONS: Serum OPG levels were independently related to BMD values and osteoporosis in post-menopausal women with and without osteoporosis.