Folate, vitamin B₁₂ and total homocysteine levels in Arab adolescent subjects: reference ranges and potential determinants.

BACKGROUND & AIMS: Elevated circulating fasting total homocysteine (tHcy) concentration is associated with an increased risk of occlusive vascular disease in adults. Important determinants of tHcy levels are folate, vitamin B(12) and vitamin B(6). This study aimed to investigate age, gender, and body mass as determinants of folate, vitamin B(12) and tHcy levels in Arab older children and adolescents and to propose population, gender and age-specific reference ranges for these biomarkers.

METHODS & RESULTS: 774 (316 boys, 458 girls) healthy 10-19 yr olds attending secondary schools in Kuwait were assessed for anthropometry and fasting blood levels of Hcy, folate and vitamin B(12). The mean (95% CI) serum levels of tHcy, folate and vitamin B(12) were respectively 6.57 μmol/L (6.42-6.73), 16.0 ng/ml (15.6-16.3) and 354.3 pg/ml (343.0-365.7). Boys had significantly higher tHcy and folate concentrations than the girls, although vitamin B(12) levels were greater in the latter. Folate and vitamin B(12) levels decreased significantly with age, while correspondingly, tHcy levels increased, with mean values (μmol/L) for boys (6.71; 8.25) and girls (5.36; 6.67) aged 10-14 yr and 14-19 yr respectively. Bivariate and multivariate analyses with adjustment for confounders such as age, gender, need for dietary control and socio-demographic variables indicated that the independent determinants of levels of tHcy were age, gender and body mass.

CONCLUSION: There is an age-related increase in tHcy in adolescents reflecting decreased levels of folate and vitamin B(12), with the suggestion that age-related reference ranges for these biomarkers be used. These observations may have implications for prevention of future atherogenic disease.