C-reactive protein and features of the metabolic syndrome in a population-based sample of children and adolescents

Background: C-Reactive protein (CRP) is a risk marker for type 2 diabetes and cardiovascular diseases. In youth, limited data are available on the distribution of high-sensitivity CRP as well as on its association with components of the metabolic syndrome. Methods: In 1999, we conducted a school-based survey of a representative sample of youths 9, 13, and 16 years of age in the province of Quebec, Canada. Standardized clinical measurements and fasting plasma lipid, glucose, insulin, and CRP concentrations were available for 2224 individuals. Results: The distribution of CRP was positively skewed. The median and 95th percentile values by age and sex ranged from <0.2 to 0.56 mg/L and from 2.72 to 6.28 mg/L, respectively. A total of 7.7% of 9-year-olds, 5.5% of 13-year-olds, and 12.8% of 16-year-olds had CRP concentrations >3.0 mg/L, the threshold defining the adult high-risk category. We observed a strong relationship between CRP concentrations and both body mass index (BMI) and fasting insulin values. The association between CRP and insulin concentration was markedly attenuated after adjustment for BMI, whereas that between CRP and BMI remained unchanged after adjustment for insulin: a 1 SD increase in BMI was associated with a 52% increase in CRP concentration. An increased CRP concentration was independently associated with a worsening of the lipid profile, whereas the association between increased CRP values and high systolic blood pressure was no longer statistically significant after adjustment for BMI. Conclusions: The metabolic correlates of excess weight, including a state of low-grade systemic inflammation, are detectable early in life. Their health impact in adults remains to be fully examined. (C) 2004 American Association for Clinical Chemistry.