Interpretation of circulating C-reactive protein levels in adults:: Body mass index and gender are a must

Objective: The recently demonstrated association between C-reactive protein (CRIP) level and body mass index (BMI) raised the question of the link between CRP and the degree of obesity. In the present study, we measured CRP in a healthy population with a wide range of BMI in order to appreciate the influence of overweight in the interpretation of CRP results in clinical use. Method: Blood donors, aged from 19 to 65 years, were included in the study. According to BMI, subjects were classified into 3 groups: A (BMI < 25 kg/m(2), n = 611); B (25-30, n = 147); C (> 30, n = 34). Results: CRP values were different among women and men. CRP progressively increased with BMI in women. These results clearly showed that average level of CRIP was quite different according to BMI and gender of the subjects and generated different normal ranges of CRP expressed in mg/L (median, 75(th) percentile): Group A: women: 0.44, 0.93; men: 0.40, 0.79, Group B: women: 1.28, 1.84; men: 0.84, 2.17, Group C: women: 3.61, 7.21; men: 1.16, 3.08. Conclusion: Our results suggest that for an inflammatory disease diagnosis, a CRP concentration of 5 mg/L is normal for obese women but is five times the 75(th) percentile for normal people.