Hypothyroidism among military infants born in countries of varied iodine nutrition status

Marcus M Cranston,Tyler C Smith,Stephanie K Brodine,Carter J Sevick,Margaret Ak Ryan

doi:10.1186/1472-6823-10-2

Marcus M Cranston, Tyler C Smith + Show 3 more

Open Access

https://doi.org/10.1186/1472-6823-10-2

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Abstract

BackgroundIodine deficiency is a global problem representing the most common preventable cause of mental retardation. Recently, the impact of subtle deficiencies in iodine intake on children and pregnant women has been questioned. This study was designed to compare hypothyroidism among infants born to US military families in countries of varied iodine nutrition status.MethodsA cohort design was used to analyze data from the Department of Defense Birth and Infant Health Registry for infants born in 2000-04 (n = 447,691). Hypothyroidism was defined using ICD-9-CM codes from the first year of life (n = 698). The impact of birth location on hypothyroidism was assessed by comparing rates in Germany, Japan, and US territories with the United States, while controlling for infant gender, plurality, gestational age, maternal age, maternal military status, and military parent's race/ethnicity.ResultsHypothyroidism did not vary by birth location with adjusted odds ratios (OR) as follows: Germany (OR 0.82, [95% CI 0.50, 1.35]), Japan (OR 0.67, [95% CI 0.37, 1.22]), and US territories (OR 1.29, [95% CI 0.57, 2.89]). Hypothyroidism was strongly associated with preterm birth (OR 5.44, [95% CI 4.60, 6.42]). Hypothyroidism was also increased among infants with civilian mothers (OR 1.24, [95% CI 1.00, 1.54]), and older mothers, especially ages 40 years and older (OR 2.09, [95% CI 1.33, 3.30]).ConclusionsIn this study, hypothyroidism in military-dependent infants did not vary by birth location, but was associated with other risk factors, including preterm birth, civilian maternal status, and advanced maternal age.

Highlights

Iodine deficiency is a global problem representing the most common preventable cause of mental retardation
These infants were predominately born in the United States to civilian mothers, who were married to activeduty military members
Hypothyroidism did not differ for infants born in Germany, Japan or US territories when compared with infants born in the United States

Summary

Introduction

Iodine deficiency is a global problem representing the most common preventable cause of mental retardation. The impact of subtle deficiencies in iodine intake on children and pregnant women has been questioned. Over 1.9 billion people, 31% of the world’s population, live in areas of iodine deficiency [1]. Iodine deficiency disorders affect over 200 million people and are the most common preventable cause of brain damage and mental retardation worldwide [2]. Public health efforts focused on severe iodine deficiency with the goal of preventing goiter and cretinism. Concerns have been raised regarding the effects of lesser degrees of iodine deficiency in vulnerable populations, such as pregnant women and children. When iodine deficiency is present during the fetal stage to the third month after birth, even mild to moderate deficiency may lead to abnormalities of psychoneuromotor and intellectual development [4,5]

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