Waist circumference is the main determinant of elevated C-reactive protein in metabolic syndrome.

Background: Metabolic syndrome (MetS) is known to increase the risk of cardiovascular disease. C-reactive protein (CRP) has been reported to be elevated in subjects with MetS. However, which component of MetS contributes mostly to the elevation has not been studied in detail.

Methods: We studied 628 apparently healthy Japanese subjects (men 262, women 366, age 19-85 years). Body mass index, waist circumference (WC), blood pressure, lipids, glucose, insulin and CRP were measured. MetS was defined according to the National Cholesterol Education Program's Adult Treatment Panel III report.

Results: In partial correlation analysis, WC showed the strongest correlation with CRP among the variables related to MetS. CRP increased as the number of MetS components increased. The mean CRP value adjusted for demographic variables was higher in subjects with MetS than those without MetS, and further adjustments with variables related to MetS revealed that the significant difference between the two groups disappeared only when further adjustment was made for WC. In multiple linear regression analysis, the independent variable that most strongly explained the CRP level was WC, which was followed by HDL-cholesterol. Finally, comparison of the CRP levels in groups stratified by abdominal obesity and the number of MetS components revealed that those with abdominal obesity tended to show higher CRP levels compared with those without abdominal obesity regardless of the number of MetS components other than WC.

Conclusions: Subjects with MetS showed higher levels of CRP and the main determinant of the CRP elevation was WC.