OBJECTIVE—Adults with the metabolic syndrome show biochemical evidence of low-grade inflammation. We sought to examine whether this is true among U.S. youth with the metabolic syndrome.

RESEARCH DESIGN AND METHODS—We used data from 1,366 participants aged 12–17 years from the National Health and Nutrition Examination Survey 1999–2000. A modification of the definition of the metabolic syndrome proposed by the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults was used. C-reactive protein (CRP) was measured by latex-enhanced nephelometry.

RESULTS—Mean and median concentrations of CRP were higher among participants who had the metabolic syndrome (mean 3.8 mg/l, geometric mean 1.8 mg/l) than among those who did not (mean 1.4 mg/l, geometric mean 0.4 mg/l). The percentage of participants with a concentration of CRP >3.0 mg/l was 38.4% among those with the metabolic syndrome and 10.3% among those without the syndrome (P = 0.007). Of the five components of the syndrome, only abdominal obesity was significantly and independently associated with log-transformed concentrations of CRP in multiple linear regression analysis.

CONCLUSIONS—Our results show that a large percentage of children and adolescents with the metabolic syndrome have elevated concentrations of CRP. Whether the elevated concentrations of CRP among children and adolescents who have the metabolic syndrome predict future adverse health events remains to be determined.