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: Michael B Zimmermann, Rita Wegmüller, Christophe Zeder, Nourredine Chaouki, Toni Torresani
• Journal: The Journal of clinical endocrinology and metabolism (J Clin Endocrinol Metab) Vol. 89 Issue 11 Pg. 5441-7 (Nov 2004) ISSN: 0021-972X [Print] United States
• PMID: 15531495 (Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Chemical References

• Thyroid Hormones
• Vitamin A

Topics

• Adolescent
• Child
• Cross-Sectional Studies
• Dietary Supplements
• Double-Blind Method
• Female
• Goiter (physiopathology)
• Humans
• Male
• Thyroid Gland (physiopathology)
• Thyroid Hormones (blood)
• Vitamin A (administration & dosage)
• Vitamin A Deficiency (drug therapy, physiopathology)