Iodine Deficiency Clinical Presentation

Updated: Oct 15, 2017
  • Author: Stephanie L Lee, MD, PhD; Chief Editor: George T Griffing, MD  more...
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Presentation

History and Physical Examination

Patients with iodine deficiency tend to come from geographic regions where iodine deficiency disorders (IDDs) are endemic. The first sign of iodine deficiency is diffuse thyroid enlargement, which becomes multinodular over time. In patients with hypothyroidism due to severe iodine deficiency, one might see signs such as dry skin, periorbital edema, and delayed relaxation phase of the deep tendon reflexes.

Goiter

Patients with IDD most commonly present with goiter. Typical endemic goiters are shown in the image below. Children present with diffuse goiters, while adults present with nodular goiters. If a goiter is large enough, patients may complain of compressive symptoms, such as hoarseness, shortness of breath, cough, or dysphagia.

Typical endemic goiters in 3 women from the Himala Typical endemic goiters in 3 women from the Himalayas, an area of severe iodine deficiency. Image courtesy of F. DeLange.

Hypothyroidism and cretinism

Individuals with severe iodine deficiency may also have hypothyroidism and may complain of fatigue, weight gain, cold intolerance, dry skin, constipation, or depression.

Cretinism is the most extreme manifestation of IDD. Cretinism can be divided into neurologic and myxedematous subtypes. These subtypes have considerable clinical overlap. Both conditions can be prevented by adequate maternal and childhood iodine intake. Neurologic cretinism is thought to be caused by severe IDD with hypothyroidism in the mother during pregnancy and is characterized by mental retardation, abnormal gait, and deaf-mutism, but not by goiter or hypothyroidism in the child.

Myxedematous cretinism is considered to result from iodine deficiency and hypothyroidism in the fetus during late pregnancy or in the neonatal period, resulting in mental retardation, short stature, goiter, and hypothyroidism.

A man and 3 females (age range, 17-20 y) with myxe A man and 3 females (age range, 17-20 y) with myxedematous cretinism from the Republic of the Congo in Africa, a region with severe iodine deficiency. Image courtesy of F. DeLange.

Mental retardation

Worldwide, iodine deficiency is the leading cause of preventable mental retardation. This became a renewed concern as the prevalence of moderate iodine deficiency in the United States among women of childbearing age increased from 4% in the 1970s to 15% by the 1990s. Although children of mothers from iodine-deficient regions may have normal thyroid function test results, they are noted to have lower language and memory performance.

Reduction in IQ has been noted in affected youth from regions of severe and mild iodine deficiency. Mental retardation as a result of iodine deficiency can be exaggerated in the setting of concomitant deficiencies of selenium or vitamin A. [20]

Postnatally, as infants and children are particularly sensitive to fluctuations in iodine intake, this population is at risk for poor mental and psychomotor development (predominantly in language and memory skills). Unlike mental retardation that occurs because of prenatal iodine deficiency, mental retardation from continued postnatal iodine deprivation may be reversible with thyroid hormone replacement.