Serum total homocysteine concentrations in adolescent and adult Americans: results from the third National Health and Nutrition Examination Survey.

BACKGROUND: The elevation of circulating total homocysteine concentrations in a fasting state is associated with an increased risk of occlusive vascular disease.

OBJECTIVE: The primary goals of this study were to describe the distribution of serum total homocysteine concentrations in the United States and to test for differences in homocysteine concentrations among sex, age, and race-ethnicity categories.

DESIGN: Using surplus sera from phase 2 of the third National Health and Nutrition Examination Survey, we measured serum total homocysteine concentrations for a nationally representative sample of 3766 males and 4819 females aged > or = 12 y.

RESULTS: Age-adjusted geometric mean total homocysteine concentrations were 9.6 and 7.9 mmol/L in non-Hispanic white males and females, 9.8 and 8.2 mmol/L in non-Hispanic black males and females, and 9.4 and 7.4 mmol/L in Mexican American males and females, respectively. Age-adjusted geometric mean total homocysteine concentrations were significantly lower in females than in males in each race-ethnicity group (P < 0.01) and were significantly lower in Mexican American females than in non-Hispanic white and non-Hispanic black females (P < 0.01). There was a significant age-sex interaction (P < 0.01), reflecting the fact that homocysteine concentrations in females tended to diverge from those in males at younger ages and converge with those in males at older ages.

CONCLUSIONS: The first data on homocysteine concentrations in a nationally representative sample of Americans confirm the age and sex differences reported previously in nonrepresentative samples. These data also indicate that differences between Mexican American and non-Hispanic females may influence circulating homocysteine concentrations.