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Objectives: To provide reference values for haematological indices in Spanish adolescents according to age and gender. Methods: A cross sectional study conducted in five Spanish cities was performed. Blood was drawn from a representative sample of 581 adolescents with age ranging from 13 to 17–18.5 yr. Age- and gender-specific means, standard deviations and percentiles were determined for the following parameters: total red blood cell counts (RBC), haemoglobin concentration (Hb), haematocrit percentage (Hct), mean corpuscular volume (MCV), mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, red cell distribution width and total white blood cell (WBC) counts as well as counts and percentage of neutrophils, lymphocytes, monocytes, eosinophils and basophils; platelet count (PLT), mean platelet volume and plateletcrit percentage. Results: Younger male subjects presented lower RBC, Hb, Hct and MCV means that their older counterpart. By contrast these differences were not observed in female subjects. As expected, RBC, Hb and Hct mean values in males were found significantly higher than in girls for all studied age groups. No significant differences were observed in WBC by age and gender. PLT values gradually decreased with age, except for females aged 17–18.5 yr. Conclusion: The present study provides reference data on the distribution of haematological indices of Spanish adolescents. These data can be useful biomarkers of the nutritional status in adolescents. [ABSTRACT FROM AUTHOR]

Background: Folate and cobalamin are responsible for healthy growth. However, the B-vitamin and homocysteine status of adolescents is not well known. The aim was to assess the status of folate, cobalamin, and homocysteine in healthy Spanish adolescents. Methods: Serum cobalamin, serum folate, homocysteine, methylenetetrahydrofolate reductase 677C>T variant, BMI, smoking habits, and Tanner stage were determined according to gender in 165 adolescents (84 females, 81 males; 13–18.5 years) using the Student’s t test, Mann-Whitney U test and χ2 test, respectively. Interactions between socioeconomic status, age group, methylenetetrahydrofolate reductase polymorphism, BMI, smoking habits, Tanner stage, and vitamin status, respectively, were examined by ANOVA or Kruskal-Wallis H test (p < 0.05). Results: Boys had markedly higher homocysteine (males 8.92 (5.51–22.94) μmol/l; females 7.91 (5.09–13.86) μmol/l), whereas girls showed higher serum cobalamin concentrations (males 540.00 (268.00–946.47) pmol/l; females 594.82 (280.63–1,559.64) pmol/l). Data are shown as medians and the 2.5th to 97.5th percentiles in parentheses. Adolescents with the homozygous variant of methylenetetrahydrofolate reductase displayed significantly higher homocysteine and lower serum folate: normal 5.73 (3.09–10.73) ng/ml serum folate, 7.57 (4.94–12.94) μmol/l homocysteine; homozygous 4.10 (2.75–7.88) ng/ml serum folate, 10.83 (7.00–22.82) μmol/l homocysteine. Conclusion: The present study provides data on the folate, cobalamin, and homocysteine status of Spanish adolescents. To assure a better assessment, revision of references for adolescents is still needed. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objective: To examine the association between cardiovascular fitness and homocysteine levels in adolescents. Design: Cross-sectional study. Setting: Madrid, Murcia, Grenada, Santander, and Zaragoza, Spain. Participants: One hundred fifty-six Spanish adolescents (76 boys and 80 girls) aged (mean±SD) 14.8±1.4 years. Main Exposures: Cardiovascular fitness was measured by the 20-m shuttle run test. Pubertal stage, birth weight, smoking status, and socioeconomic status were determined, and the sum of 6 skinfold thickness measurements, and serum folic acid and vitamin B12 levels were measured. Methylenetetrahydrofolate reductase (MTHFR; 677C>T genotype) polymorphism was done by DNA sequencing. Main Outcome Measure: Fasting homocysteine levels. Results: Mean values of homocysteine were significantly higher in the MTHFR 677CT and TT genotype subgroups compared with the CC genotype subgroup in adolescent boys, whereas in adolescent girls, mean values of homocysteine were significantly higher in the MTHFR 677CT and TT genotype subgroup compared with the CC and CT genotype subgroups. Multiple regression analyses showed that cardiovascular fitness was significantly associated with homocysteine levels in female adolescents after controlling for potential confounders including the MTHFR 677C>T genotype (β= -0.40; semipartial correlation = -0.35; P =.007). No associations were found between cardiovascular fitness and homocysteine levels in male adolescents (β=0.12; semipartial correlation=0.08; P =.51). Conclusion: The results suggest that cardiovascular fitness is negatively associated with homocysteine levels in female adolescents after controlling for potential cofounders including MTHFR 677C>T genotype. [ABSTRACT FROM AUTHOR]