Obesity is the major determinant of elevated C-reactive protein in subjects with the metabolic syndrome

Abstract

Objective: To investigate the relationship between C-reactive protein (CRP) and various characteristics of the metabolic syndrome.

Design: Population-based cross-sectional study.

Subjects: A total of 1929 subjects undergoing a medical examination in a preventive medicine clinic (age, 50+/-10 y; 63% males).

Results: The proportion of subjects with CRP levels above the cut point generally used to indicate an obvious source of infection or inflammation (>10 mg/l) was 3, 7, and 15% in subjects who were normal weight, overweight, and obese, respectively. Subjects with obesity had markedly higher CRP level compared to patients without obesity regardless of whether they had the metabolic syndrome. However, there was no significant difference in CRP levels between nonobese subjects without the metabolic syndrome and subjects in whom the diagnosis of the metabolic syndrome was based on criteria other than obesity (adjusted geometric mean CRP 1.75 vs 2.08 mg/l, P=0.79). Similarly, CRP levels did not differ among obese subjects with and without the metabolic syndrome (adjusted geometric mean CRP 3.22 vs 3.49 mg/l, P=0.99). There was a linear increase in CRP levels with an increase in the number of metabolic disorders (P(trend) <0.0001), which was substantially diminished after controlling for body mass index (BMI) (P(trend)=0.1). Stepwise multivariate linear regression analysis identified BMI, triglyceride levels, HDL cholesterol levels (inversely), and fasting glucose as independently related to CRP levels. However, BMI accounted for 15% of the variability in CRP levels, whereas triglycerides, HDL cholesterol and fasting glucose levels accounted for only approximately 1% of the variability in CRP levels.

Conclusion: Obesity is the major factor associated with elevated CRP in individuals with the metabolic syndrome. CRP levels in the range suggesting a source of infection or inflammation (>10 mg/l) are more common among obese subjects than in nonobese subjects.