Endocrine Abstracts

Postmenopausal osteoporosis is characterized by lower bone mass, loss of structural integrity, and sometimes becomes life-threatening. The development of postmeno-pausal osteoporosis is multifactorial. Estrogen plays a preventing role in the bone resorption inhibiting the secretion of proinflammatory IL1 and TNFα cytokines. IL17 proinflammatory citokine is a new candidate in the pathogenesis of osteoporosis. IL17 levels are increased in estrogen deficiency.

The relationship between serum IL17A levels and estradiol levels, as well as bone mineral density (BMD) was studied in 72 post- and 22 premenopausal women. Enzyme-linked immunosorbent assay for IL17A and chemiluminescence method for estradiol detections were used. Dual energy X-ray absorptiometry (DXA) was applied for BMD measurement in the lumbar spine (L1–L4) and femoral (total and neck) regions.

The estradiol levels were significantly higher in premenopausal women compared with postmenopausal ones (239.44±226.17 vs 74.21±4.44 pmol/l, P<0.0001). Increased IL17A levels were demonstrated in postmenopause in comparison with those in premenopause (3.5±0.56 vs 2.88±0.08 ng/ml, P<0.0001). Seventy eight women out of 94 had lower estradiol levels (<80 pmol/l) and demonstrated elevated IL17A levels in comparison with 16 women who had estrogen levels in the normal range (3.43±0.56 vs 3.01±0.38 ng/ml, P<0.0001). IL17A levels were higher in osteoporotic women than in osteopenic ones (3.65±0.61 vs 3.31±0.0.08 ng/ml, P<0.013 in lumbar region, and 4.19±1 vs 3.46±0.51 ng/ml, P<0.015 in femoral region). In postmenopause, the differences in BMDs between women with low and high (>3.04 ng/ml=mean of all women+2S.D.) IL17A levels were significant in femoral region, particularly in femoral neck region (0.72±0.1 vs 0.64±0.14 g/cm², P<0.007). A strong correlation was demonstrated between IL17A levels and BMDs of all studied regions in postmenopause.

The results highlighted a relationship between IL17A and estradiol levels, as well as BMDs. Estrogen deficiency in postmenopause can accelerate the bone-wasting through increased IL17A levels, particularly in femoral neck region.