Hormone replacement therapy and interrelation between serum interleukin-6 and body mass index in postmenopausal women: A population-based study

Postmenopausal women are at increased risk to develop osteoporosis, coronar y artery disease, heart failure, and hypertension. Interleukin-6 (IL-6) may be a pathogenetic element in these disorders. Serum IL-6 levels increase d uring aging and seem to be related to increased body fat mass. In the prese nt retrospective study we aimed to investigate the role of hormone replacem ent therapy (HRT) on serum IL-6 levels and the interrelation of IL-6 and bo dy fat mass. Parameters were assessed in a population-based sample of postm enopausal women (n = 302) and, for comparison, 245 men of the same age. Wom en with HRT (n = 92) had significantly lower serum IL-6 levels compared to subjects without HRT, which was independent of age, antihypertensive therap y, smoking habits, and blood pressure (1.5 +/- 0.1 vs. 2.9 +/- 0.6 pg/mL; P = 0.017). In women without HRT, the body mass index (BMI) was correlated w ith serum IL-6 levels (P < 0.001). Multivariate analysis controlling simult aneously for the effects of blood pressure and heart rate confirmed the pos itive correlation (P = 0.001). However, in subjects with HRT no such correl ation between IL-6 and BMI was demonstrated, which was confirmed after cont rolling covariates. In male subjects, BMI correlated with serum IL-6 (P = 0 .009), which was, however, blunted after controlling for blood pressure and heart rate, probably indicating an influence of the sympathetic nervous sy stem on this interrelation. In conclusion, women receiving HRT display lowe r serum IL-6 levels and a blunted interrelation of IL-6 and BMI. As IL-6 ma y be a pathogenetic factor in age-related diseases, HRT-related inhibition of IL-6 secretion could be an important element for the favorable effects o f HRT in postmenopausal women.