Sex differences in the relationship between C-reactive protein and body fat

C-reactive protein (CRP) levels are significantly influenced by adiposity and are higher in women compared with men. We postulated that there may be sex differences in the relationship between CRP and body fat.

We measured CRP and body fat parameters in 1166 men and 1413 women ages 30-65 in the population-based Dallas Heart Study. Total fat mass (TFM) was measured using dual-energy x-ray absorptiometry scanning and was subdivided into truncal fat (TrF) and lower body fat (LBF). The TrF/LBF ratio was used to measure fat distribution. Abdominal fat compartments (ip and sc) were measured using magnetic resonance imaging. Log-transformed CRP was used as the outcome variable in sex-combined models with interaction tests.

Median body mass index was higher in women than in men (29.9 vs. 28.2 kg/m(2)), as was TFM (29.7 vs. 20.5 kg) (P < 0.001 each). TFM was linearly associated with log CRP in both sexes, with a steeper slope of association in women (P interaction = 0.003). CRP increased to a greater degree with increasing TrF (P interaction = 0.0004) in women compared with men, even after adjustment for TFM; values were similar across sexes for LBF. Fat distribution (TrF/LBF ratio) was more strongly associated with CRP levels in women vs. men (R(2) adjusted for TFM = 0.04 vs. 0.008). Greater increases in CRP were also observed with increasing ip and sc fat in women compared with men.

The quantity and distribution of body fat influence CRP to a greater extent in women compared with men. Adiposity as a contributor to subclinical inflammation may be particularly relevant in women.