Effects of progestins on estrogen-induced increase in C-reactive protein in postmenopausal women

C-reactive protein (CRP) represents an independent risk factor for coronary disease and stroke. Because oral estrogens increase CRP levels, with inflammatory and thrombotic consequences, we determined whether the co-administration of a progestin might modify the estrogenic effect on CRP.

In a non-randomized, non-blinded study, we measured C-reactive protein serum concentrations with high-sensitivity technique (hs-CRP) in 163 healthy postmenopausal women divided into groups as follow: 52 not taking hormones (referent group), and 111 taking hormone replacement therapy (HRT) (42 of whom treated with unopposed estrogen, and 69 with an estrogen/progestin combination).

Compared with non-users of hormones, median CRP levels were 66% (95% confidence interval: from 44 to 89%) higher and 112% (95% confidence interval: from 89 to 168%) higher among women using a combined estrogen/progestin regimen and, respectively, among women taking unopposed estrogen [1.54 mg/L in the referent group; 2.56 mg/L in the estrogen/progestin group (P=0.032), and 3.27 mg/L in the unopposed estrogen group (P=0.004)]. Furthermore, there was no difference in CRP distributions between women taking different types of progestins.

concurrent progestin administration may attenuate estrogen's pro-inflammatory effects, independently on the type of used progestin.