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

Background: C-reactive protein (CRP) levels are significantly influenced by adiposity and are higher inwomencompared with men.Wepostulated that theremaybe sex differences in the relationship between CRP and body fat. Methods: 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. Results: Median body mass index was higher in women than in men (29.9 vs. 28.2 kg/m²), 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 (R² 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. Conclusions: 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.