The aim of this study was to compare the effects of transdermal estrogen and oral estrogen on C-reactive protein (CRP) and inflammatory cytokines in a group of 21 post-menopausal women. Previous studies demonstrate that oral estrogen therapy causes a sustained increase in CRP which suggests a pro-inflammatory effect. Transdermal estradiol (100µg/day), oral conjugated estrogen (0.625mg/day) or a placebo was administered for a period of 8 weeks. Prior to and following the 8-week period, CRP, IL-1-beta, IL-6 and tumour necrosis factor-alpha, IGF-1, and a hepatic-derived anabolic peptide levels were measured. Overall, the study found that oral estrogen increased CRP levels by a first-pass hepatic effect, whereas transdermal estradiol did not. This finding is clinically significant as CRP is an independent predictor of cardiovascular events.
