title: The effects of vitamin A deficiency and vitamin A supplementation on thyroid function in goitrous children.
abstract: In developing countries, children are at high risk for both the iodine deficiency disorders (IDD) and vitamin A deficiency (VAD). The study aim was to determine the effects of VAD and vitamin A (VA) supplementation on thyroid function in an area of endemic goiter. In a double-blind, randomized, 10-month trial, Moroccan children with IDD and VAD (n = 138) were given iodized salt and either VA (200,000 IU) or placebo at 0 and 5 months. At 0, 5, and 10 months, measurements of VA status and thyroid function were made. At baseline, increasing VAD severity was a predictor of greater thyroid volume and higher concentrations of TSH and thyroglobulin (P < 0.001). In children with VAD, the odds ratio for goiter was 6.51 (95% confidence interval, 2.94, 14.41). VAD severity was also a strong predictor of higher concentrations of total T(4) (P < 0.001); the odds ratio for hypothyroidism in VAD was 0.06 (95% confidence interval, 0.03, 0.14). During the intervention, mean thyroglobulin, median TSH, and the goiter rate significantly decreased in the VA-treated group compared with those in the placebo group (P < 0.01). The findings indicate that VAD in severely IDD-affected children increases TSH stimulation and thyroid size and reduces the risk for hypothyroidism. This effect could be due to decreased VA-mediated suppression of the pituitary TSHbeta gene. In IDD- and VAD-affected children receiving iodized salt, concurrent VA supplementation improves iodine efficacy.
authors.affiliation: Human Nutrition Laboratory, Swiss Federal Institute of Technology Zurich, Seestrasse 72/Postfach 474, CH-8803 Ruschlikon, Switzerland. michael.zimmermann@ilw.agrl.ethz.ch.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Zimmermann
authors.forename: Rita
authors.initials: R
authors.lastname: Wegmüller
authors.forename: Christophe
authors.initials: C
authors.lastname: Zeder
authors.forename: Nourredine
authors.initials: N
authors.lastname: Chaouki
authors.forename: Toni
authors.initials: T
authors.lastname: Torresani
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006042:Goiter / Q000503:physiopathology*; D006801:Humans; D008297:Male; D013961:Thyroid Gland / Q000503:physiopathology*; D013963:Thyroid Hormones / Q000097:blood; D014801:Vitamin A / Q000008:administration & dosage*; D014802:Vitamin A Deficiency / Q000188:drug therapy* / Q000503:physiopathology
chemical_list: D013963:Thyroid Hormones; D014801:Vitamin A