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 mu mol/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 (mu mol/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. (C) 2010 Elsevier B.V. All rights reserved.