An Overview of Iodine Deficiency

Signs, Symptoms, Diagnosis, and Treatment

Iodine deficiency is a nutritional imbalance resulting from not consuming enough iodine in your diet. Iodine is an essential component of two hormones produced by your thyroid: thyroxine (T4) and triiodothyronine (T3). Without consuming enough iodine in your diet, your thyroid will be unable to produce enough of either hormone and you will experience symptoms related to hypothyroidism, or the under-functioning of your thyroid.

Your thyroid is a butterfly-shaped gland that is located in the front and lower part of your neck. Your thyroid is an endocrine gland which produces hormones that play an important part in both infants and adults. In infants, thyroid hormones are important in the development of their brains and the growth of their bodies.

In adults, thyroid hormones affect all of the organs' functions and your metabolism. If you do not consume enough dietary iodine, side-effects from hypothyroidism can be widespread and affect many different functions of your body.

Prevalence

Despite worldwide efforts to make iodine easily accessible through diets, approximately 2 billion people are still at risk of having an iodine deficiency disorder.

While 86 percent of the world population has access to iodized salt, there are still many countries not considered to be iodine sufficient.

The Chinese were first credited for identifying a link between iodine and the reduction of goiters (a side effect of hypothyroidism). While the Chinese did not have knowledge of iodine, they found that consumption of seaweed and burnt sea sponge reduced the risk of goiters as early as 3600 B.C.

In the early 1800s, the manufacturing of gunpowder led to initial iodine discoveries. In turn, this led to further discoveries of thyroid involvement with iodine deficiency disorders. By the 1920s in the United States of America, iodized salt was available in the marketplace and noted to have a major impact in reducing the prevalence of iodine deficiency.

Causes

There are certain groups that are more at risk of developing iodine deficiency. These risk factors include people who:

  • do not consume iodized salt
  • live in an area that has iodine-deficient soil (mountainous areas and areas that are prone to flooding)
  • do not meet dietary iodine requirements while also consuming foods high in goitrogens (substances that reduce the intake of iodine in the thyroid such as soy, cabbage, and broccoli)
  • are pregnant

Areas that are at high risk of having iodine-deficient soil include the Himalayas, Alps, and Andes (mountainous areas), as well as South and Southeast Asia (river valleys with flooding).

Daily Requirements

According to the World Health Organization (WHO), the amount of iodine you need to consume changes according to your age as well as if you are pregnant and/or lactating.

The Food and Nutrition Board at the Institute of Medicine of the National Academies has a slightly different recommendation that is a little higher for infants and toddlers:

  • 0 to 6 months old: 110 mcg
  • 7 to 12 months old: 130 mcg
  • 1 to 8 years old: 90 mcg
  • 9 to 13 years old: 120 mcg
  • 14 years old and above: 150 mcg
  • Pregnant women: 220 mcg
  • Lactating women: 290 mcg

Foods With Iodine

While iodine can be consumed in iodized salt, you can also get adequate amounts of iodine in the foods that you consume. These types of food include:

  • Saltwater fish
  • Seaweed
  • Shrimp and other seafood
  • Dairy products (in the United States)
  • Breads and cereals (in the United States)
  • Fruits and vegetables (only if they come from soil rich in iodine)

Dairy products as well as breads and cereals can be sources of iodine in the United States due to manufacturing or cleaning techniques that are used. You may also find multi-vitamins that provide iodine if they contain potassium iodide or sodium iodide.

Iodine deficiency symptoms
Illustration by JR Bee, Verywell.

Symptoms

One of the most common findings related to iodine deficiency is the presence a lump on your neck. This lump, also known as a goiter, is not usually a problem and is mostly a cosmetic nuisance.

However, if the lump becomes big enough, it may cause you to cough, have difficulty swallowing, or have difficulty with breathing.

Problematic symptoms of goiters may be caused when the goiter starts to compress your trachea or your esophagus.

Depending on your iodine intake, a goiter may also cause you to have symptoms related to hyperthyroidism (over-functioning thyroid) or hypothyroidism (under-functioning thyroid). If your intake of iodine is only a little below average, you are more likely to have symptoms related to hyperthyroidism.

This occurs because the goiter causes an autonomous region in the thyroid that does not act regularly and produces too much of the thyroid hormone. However, if you consume very low levels of iodine, the goiter will likely cause symptoms of hypothyroidism.

Cretinism

Fetuses and infants exposed to iodine deficiency are at risk of developing cretinism. Cretinism is characterized by intellectual disability followed by other symptoms if the iodine deficiency continues into infancy.

One type of cretinism is called neurological cretinism. This occurs when iodine levels are sufficient during infancy, but the fetus was iodine deficient during pregnancy. This could cause deaf-mutism (deafness that leads to being unable to speak), gait disturbance, and/or muscles spasticity.

Another type is called myxedematous cretinism, which occurs when the baby is iodine deficient both during infancy and pregnancy. As a result, the baby may grow to be below-average height and/or may have hypothyroidism.

Diagnosis

While there is no single test to diagnose iodine deficiency, there are several methods that your doctor may use to help determine if you have an iodine deficiency. The most likely cause in seeing a doctor related to iodine deficiency as an adult is the presence of a goiter.

When evaluating you for an iodine deficiency-related goiter, your doctor will want to know what types of foods you eat and whether or not you use iodized salt or non-iodized salt. Your doctor may choose to palpate (examine by touch) your neck; however, this is more for descriptive purposes than for an actual diagnosis.

If you have a goiter, your doctor will likely order an ultrasound of your neck to determine the size of the goiter, the location, and other aspects of your thyroid.

A urine sample is a good short-term check of iodine sufficiency. Approximately 90 percent of all iodine ends up being excreted in your urine.

A urine test could lead to one of the following results:

  • mild deficiency (50 to 99 mcg of iodine per liter)
  • moderate deficiency (20 to 49 mcg of iodine per liter)
  • severe deficiency (less than 20 mcg of iodine per liter)

While a urine test is a good indicator of your current iodine sufficiency, it does not provide adequate information as to your long-term iodine status.

Serum thyroglobulin concentration is a blood test that can help confirm the long-term severity of the deficiency, as it is a protein that is produced by the thyroid.

Treatment

In uncomplicated iodine deficiency, correcting nutritional intake of iodine is the only treatment necessary. If you are suffering from a goiter, nutritional correction may reduce the size of the goiter somewhat. Depending on the size of the goiter, your doctor may recommend taking levothyroxine (thyroid hormone replacement medication) as well as increasing your iodine intake.

However, older children and adults may not have a large reduction in goiter size with these options. Radioactive iodine may be used in some cases to treat multiple goiters causing hyperthyroidism; however, the resulting effects of this treatment may lead to hypothyroidism.

If you have a goiter that is causing pain, difficulty swallowing, or difficulty breathing, then surgery is the recommended option. Following surgery, your doctor may need to have you take thyroid hormone replacement therapy depending on how much of your thyroid was removed.

A Word From Verywell

Iodine deficiency can result in many signs, symptoms, and in some cases, severe health issues. This is because iodine is an essential component to keeping our thyroid gland functioning—our thyroid affects many essential bodily functions. If you are concerned you are not getting enough iodine in your dietary foods, it is best to consult with your doctor to be sure you are receiving an adequate intake of iodine.

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