URINARY EXCRETION OF WATER-SOLUBLE VITAMINS (C, B1, B2, AND B6) IN HEALTHY CHILDREN OF PRESCHOOL AND SCHOOL AGE: A CROSS-SECTIONAL STUDY

Abstract

Background . Children of preschool and school age are at risk of developing vitamin deficiency. Screening of the vitamin provision of children remains an urgent problem of pediatrics. Objective. Our aim was to determine the prevalence of low excretion of watersoluble vitamins among healthy preschool and school-age children. Methods. The study was conducted in March-April 2017. We determined the urinary excretion (fasting morning portion collected during 30–120 min after night-time urination) of metabolites of vitamins C, B 1 , B 2 , and B 6 in healthy children. Riboflavin (vitamin B 2 metabolite) was determined spectrophotometrically by titration with a riboflavin-binding apoprotein; 4-pyridoxyl acid (vitamin B 6 metabolite) and thiamine (vitamin B 1 metabolite) — by fluorescent method, ascorbic acid (vitamin C metabolite) — by visual titration with Tillman’s reagent. The excretion considered to be low (equivalent to vitamin deficiency) when thiamine excretion was < 7, 10, 11, and 12 μg/h and riboflavin < 6, 9, 10, and 13 μg/h in children aged 3–5, 6–8, 9–11, and above 12 years, respectively; 4-pyridoxylic acid — < 40, 60, and 70 μg/h in children aged 3–5, 6–8, and ≥ 9 years, ascorbic acid — < 0.2 and 0.4 mg/h in children aged 3–11 and ≥ 12 years, respectively. Results. Metabolites were excreted in 39 children (20 girls), 14 of them aged 4–6 years and 25 children aged 7–14 years. A low level of ascorbic acid excretion was found in 13 (33%) children, of thiamine — in 24 (62%), of riboflavin — in 16 (41%), of 4-pyridoxyl acid — in 26 (67%). Low excretion of at least one vitamin metabolite was detected in 30 (77%) children, of 3 or more metabolites simultaneously — in 15 (39%). Conclusion. A low level of urinary excretion of metabolites of at least one water-soluble vitamin (C, B 1 , B 2 , and B ≥ ) occurs in most preschool and schoolage children.