Distribution of and factors associated with serum homocysteine levels in children: Child and Adolescent Trial for Cardiovascular Health.

CONTEXT Although evidence suggests that homocysteine is a risk factor for cardiovascular disease in adults, little information exists on homocysteine levels in children. OBJECTIVES To describe the distribution of serum homocysteine concentrations among children and to examine the association between homocysteine levels and several characteristics, including serum levels of folic acid and vitamins B12 and B6. DESIGN Cross-sectional analysis. SETTING School-based cohort from California, Louisiana, Minnesota, and Texas. PARTICIPANTS A total of 3524 US schoolchildren, aged 13 and 14 years, from the Child and Adolescent Trial for Cardiovascular Health (completed in 1994). Measurement was conducted in 1997. MAIN OUTCOME MEASURE Nonfasting serum total homocysteine concentration. RESULTS The distribution of homocysteine values ranged from 0.1 to 25.7 micromol/L (median, 4.9 micromol/L). Geometric mean homocysteine concentration was significantly higher in boys (5.22 micromol/L) than girls (4.84 micromol/L); blacks (5.51 micromol/L) than whites (4.96 micromol/L) or Hispanics (4.93 micromol/L); nonusers of multivitamins (5.09 micromol/L) than users (4.82 micromol/L); and smokers (5.19 micromol/L) than nonsmokers (5.00 micromol/ L). Serum homocysteine was significantly inversely correlated with serum levels of folic acid (r= -0.36; P = .001), vitamin B12 (r = -0.21; P = .001), and vitamin B6 (r = -0.18; P = .001). Serum homocysteine was not significantly associated with serum lipid levels or family history of cardiovascular disease and was only weakly related to body mass index and systolic blood pressure. After multivariate adjustment, homocysteine remained independently associated with sex, race, serum folic acid and vitamin B12 levels, and systolic blood pressure. CONCLUSIONS The distribution of homocysteine levels in children is substantially lower than that observed for adults; however, a small percentage of children are still potentially at elevated risk for future cardiovascular disease. Serum folic acid may be an important determinant of homocysteine levels in children.