A systematic review and meta-analysis of 24-h urinary output of children and adolescents: impact on the assessment of iodine status using urinary biomarkers.

PURPOSE: Urinary iodine concentration (UIC (µg/ml) from spot urine samples collected from school-aged children is used to determine the iodine status of populations. Some studies further extrapolate UIC to represent daily iodine intake, based on the assumption that children pass approximately 1 L urine over 24-h, but this has never been assessed in population studies. Therefore, the present review aimed to collate and produce an estimate of the average 24-h urine volume of children and adolescents (> 1 year and < 19 years) from published studies. METHODS: EBSCOHOST and EMBASE databases were searched to identify studies which reported the mean 24-h urinary volume of healthy children (> 1 year and < 19 years). The overall mean (95% CI) estimate of 24-h urine volume was determined using a random effects model, broken down by age group. RESULTS: Of the 44 studies identified, a meta-analysis of 27 studies, with at least one criterion for assessing the completeness of urine collections, indicated that the mean urine volume of 2-19 year olds was 773 (654, 893) (95% CI) mL/24-h. When broken down by age group, mean (95% CI) 24-h urine volume was 531 mL/day (454, 607) for 2-5 year olds, 771 mL/day (734, 808) for 6-12 year olds, and 1067 mL/day (855, 1279) for 13-19 year olds. CONCLUSIONS: These results demonstrate that the average urine volume of children aged 2-12 years is less than 1 L, therefore, misclassification of iodine intakes may occur when urine volumes fall below or above 1 L. Future studies utilizing spot urine samples to assess iodine status should consider this when extrapolating UIC to represent iodine intakes of a population.

Sleep timing is associated with diet and physical activity levels in 9-11-year-old children from Dunedin, New Zealand: the PEDALS study.

It is well documented that short sleep duration is associated with excess body weight and poor food intake in children. It has been suggested that sleep timing behaviour may also be an important predictor of weight and other related behaviours, independent of sleep duration; however, there is a lack of research investigating these relationships. The present study investigated sleep timing in association with diet and physical activity levels in 439 children aged 9-11 years old from New Zealand. Sleep and physical activity data were collected using accelerometry, and food choice using a short food-frequency questionnaire. Participants were classified into one of four sleep timing behaviour categories using the median split for sleep-onset and -offset times. Differences between sleep timing groups for weekly consumption frequency of selected food groups, dietary pattern scores and minutes of moderate-to-vigorous physical activity were examined. Children in the late sleep/late wake category had a lower 'Fruit & Vegetables' pattern score [mean difference (95% CI): -0.3 (-0.5, -0.1)], a lower consumption frequency of fruit and vegetables [mean weekly difference (95% CI): -2.9 (-4.9, -0.9)] and a higher consumption frequency of sweetened beverages [mean weekly difference (95% CI): 1.8 (0.2, 3.3)] compared with those in the early sleep/early wake category. Additionally, children in the late sleep/late wake category accumulated fewer minutes of moderate-to-vigorous physical activity per day compared with those in the early sleep/early wake category [mean difference (95% CI): -9.4 (-15.3, -3.5)]. These findings indicate that sleep timing, even after controlling for sleep duration, was associated with both food consumption and physical activity.

Iron status of pregnant Indian women from an area of active iron supplementation.

OBJECTIVE: The aim of this study was to investigate the iron status of pregnant tribal women from Ramtek, Nagpur, Maharashtra, India using a combination of indices. METHODS: A community-based observational study was conducted to assess iron status using a convenience sample of pregnant Indian tribal women from Ramtek. Pregnant women were recruited at 13 to 22 wk gestation (first visit; n = 211) and followed to 29 to 42 wk gestation (second visit; n = 177) of pregnancy. Sociodemographic and anthropometric data; iron supplement intake; and blood samples for estimating hemoglobin (Hb), serum ferritin (SF), soluble transferrin receptor (sTfR), and C-reactive protein (CRP) were obtained. RESULTS: The mean (SD) Hb concentration at recruitment was 106 (15) g/L and 106 (14) g/L at the second visit; 41% of the women at recruitment and 55% at second visit were anemic (14% higher, P < 0.001). No women at recruitment and 3.7% at second visit had SF concentration < 15 ng/mL; and 3.3% at recruitment and 3.9% at the second visit had sTfR > 4.4 ng/mL (0.6% higher, P = 0.179). Almost 62% and 71% of pregnant women used iron supplements at both visits, respectively. Iron supplement intake > 7 d in the preceding month improved the Hb concentration by 3.23 g/L and reduced sTfR concentration by 13%; women who were breastfeeding at the time of recruitment had 11% higher SF concentration. CONCLUSIONS: The iron indices suggest that pregnant tribal women of central India, although anemic, had good iron status. Use of iron supplements > 7 d in the preceding month improved iron status; however, non-iron-deficiency anemia persisted in this group.