title: Iron status and linear growth: a prospective study in school-age children.
abstract: BACKGROUND
  Studies regarding the role of iron on linear growth have yielded heterogeneous results. Some trials indicate that iron supplementation of iron-replete infants leads to slower-length gain. However, little is known of the relation between iron status and linear growth in school-age children.
  
  
  METHODS
  We quantified plasma ferritin, mean corpuscular volume (MCV), and hemoglobin in 2714 children aged 5-12 years at recruitment into a cohort study. Height was measured periodically for a median of 30 months. Height-for-age Z-scores (HAZ) were calculated using the World Health Organization growth reference. Mixed effects models with restricted cubic splines were used to construct population HAZ-for-age growth curves for sex- and age-specific quartiles of each iron status indicator.
  
  
  RESULTS
  Ferritin and MCV were each inversely related to attained HAZ among boys after the adjustment for baseline age, baseline body mass index-for-age Z-score and socioeconomic status. There was a decreasing monotonic relation between quartiles of ferritin and estimated change in HAZ from ages 6 to 14 years (P trend=0.001); boys in the 4th quartile experienced a HAZ change that was 0.46 Z lower than that of boys in the 1st quartile (P=0.0006). Similarly, we observed smaller HAZ change among boys in the highest quartile of MCV in comparison with those in the 1st quartile (P trend=0.001). Hemoglobin was not related to linear growth in boys. None of the iron-status indicators were associated with linear growth in girls.
  
  
  CONCLUSIONS
  Higher iron status, as indicated by ferritin and MCV, is related to slower linear growth in iron-replete school-age boys.
authors: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA. perngwei@umich.edu
authors: W
authors: W
authors: Perng
authors: M
authors: M
authors: Mora-Plazas
authors: C
authors: C
authors: Marin
authors: E
authors: E
authors: Villamor
mesh_terms: D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000453:epidemiology; D001827:Body Height; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D015331:Cohort Studies; D003105:Colombia / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005527:Food, Fortified / Q000009:adverse effects; D006130:Growth Disorders / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D019190:Iron Overload / Q000097:blood / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D019266:Iron, Dietary / Q000008:administration & dosage / Q000009:adverse effects*; D008137:Longitudinal Studies; D008297:Male; D018673:Nutrition Policy; D009752:Nutritional Status; D015995:Prevalence; D011446:Prospective Studies; D012720:Severity of Illness Index; D012727:Sex Characteristics
chemical_list: D019266:Iron, Dietary