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Iodine Deficiency

What is iodine deficiency?

Iodine deficiency is caused by a lack of iodine, a chemical element essential to the body's physical and mental development, in a person's diet. It is the single most common cause of preventable mental retardation and brain damage in the world.

Is iodine deficiency common in the United States?

Iodine deficiency is now rare in the U.S. as a result of widespread distribution of foods from iodine sufficient areas. The incidence of iodine deficiency occurs in certain geographical areas at higher altitudes with iodine depleted soil - usually in areas away from the seacoast and in countries where salt is not fortified with iodine.

Does iodine deficiency affect women more than men?

Iodine deficiency is more prevalent in women than in men, and more common in pregnant women and adolescents.

What is the role of iodine in the body?

Iodine is an essential element for thyroid function, necessary for the normal growth, development and functioning of the brain and body. It also influences a variety of metabolic processes in the body (converting food to energy, regulating growth and fertility, and maintaining body temperature).

What are the effects of iodine deficiency?

When the body becomes iodine-deficient the consequences can affect a person both physically and mentally. After many months of iodine deficiency a person may develop a goiter (an unsightly swelling of the thyroid gland in front of the neck), hypothyroidism and reduced mental function. It also increases the risk of still birth and infant deaths.

Iodine-deficient women may give birth to babies with severe mental and neurological impairment. If this deficiency occurs during infancy or childhood, it causes irreversible mental retardation, growth failure, speech and hearing defects, among others. Even mild deficiency may cause a low intellectual capacity.

What is hypothyroidism?

Hypothyroidism refers to any state in which thyroid hormone production is below normal. There are many disorders that result in hypothyroidism that may directly or indirectly involve the thyroid gland. Since the thyroid hormone affects growth, development and many cellular processes, inadequate thyroid hormone has widespread consequences for the body.

What are the symptoms of hypothyroidism?

The symptoms of hypothyroidism are often subtle. They are not specific, which means they can mimic the symptoms of many other conditions. And patients with mild hypothyroidism often have no symptoms.

Symptoms of hypothyroidism generally become more obvious as the condition worsens. Common symptoms include:

As the disease becomes more severe, there may be puffiness around the eyes, a slowing of the heart rate, a drop in body temperature and heart failure. In its most profound form, severe hypothyroidism may lead to a life-threatening coma. This condition requires hospitalization and immediate treatment with thyroid hormones given by injection. If left untreated, hypothyroidism can lead to an enlarged heart, worsening heart failure and an accumulation of fluid around the lungs.

How is hypothyroidism diagnosed?

If a patient is experiencing the symptoms listed above, a blood test can confirm a diagnosis of hypothyroidism.

How is hypothyroidism treated?

Hypothyroidism is generally treated with iodine and or/medication to support thyroid hormones. A person with hypothyroidism may require life-long supplementation and follow-up care. Consult your doctor about treatment options available.

How is iodine deficiency treated?

Once iodine deficiency is diagnosed, consult your doctor about treatment options. Commonly, iodine preparations are prescribed. In deciding to use iodine preparations, the risks of taking them must be weighed against the good it will do. This is a decision you and your doctor will need to make.

What foods contain iodine?

In the United States, iodine is added to table salt so it is the primary food source of iodine. Iodine is also widely available in the following foods:

What are the recommended daily allowances for iodine?

The following are the recommended daily allowances for iodine:

Because iodine cannot be stored for long times in the body, tiny amounts must be consumed regularly, but food grown in iodine poor soil will not provide sufficient dietary iodine. Most people, however, are able to meet their iodine requirements by eating seafood, seaweed, iodized salts and plants grown in iodine-rich soil.

U-M Health System Related Site:
U-M Internal Medicine - Endocrinology & Metabolism

Reviewed by Roger J. Grekin, MD, UMHS Department of Internal Medicine, January 2002