Abstract:

Objective To compare the serum levels of estradiol and sex hormone-binding globulin (SHBG) between postmenopausal females patients with osteoarthritis (OA) and osteoporosis (OP), analyse their possible correlations with serum osteoprotegerin (OPG) and bone mineral densities (BMD) in the proximal femur and lumbar region, and explore the mechanism of SHBG in the development of OA and OP. Methods Sixty postmenopausal female patients with OA and 60 postmenopausal female patients with OP were selected. Anthropometric parameters were measured, and serum levels of estradiol, SHBG and OPG were quantified with radioimmunoassay or ELISA. Free estradiol index (FEI) was also calculated by the ratio of serum estradiol to SHBG. Results The body weight, body mass index and BMD in OA group were higher than those in OP group. There was no significant difference in serum estradiol level between two groups (P=0.124). SHBG and OPG levels in OP group were significantly higher than those in OA group [SHBG: (74.98±8.90) nmol/L vs (66.38±9.74) nmol/L，P<0.01；OPG: (6.94±1.18) pmol/L vs (4.67±1.28) pmol/L，P<0.01]. FEI in OP group was significantly lower than that in OA group (0.63±0.27 vs 0.75±0.31，P<0.05). Serum SHBG negatively correlated, while FEI positively correlated with BMD in the proximal femur and lumbar region in both groups. Conclusion The differences in serum SHBG levels may determine the differences in active estradiol levels, and eventually result in the differences in BMD and bone micro-structures between postmenopausal female patients with OA and OP.

Key words: osteoarthritis, osteoporosis, estrogen, sex hormone-binding globulin