What is iodine deficiency?

You need a certain amount of iodine in your body in order for it to make a chemical known as thyroid hormone. Thyroid hormone controls your metabolism and other important body functions.

Low levels of iodine are not the only cause of low thyroid function. But a lack of iodine can cause an abnormal enlargement of the thyroid gland, known as a goiter, and other thyroid problems. In children, it can cause mental disabilities.

Your body doesn’t naturally make iodine, so the only way to get this nutrient is through your diet. Adults typically require 150 micrograms (mcg) per day. Pregnant and breastfeeding women need 200 mcg per day. Iodine is found in many types of foods. It’s most concentrated in foods like:

  • fish
  • eggs
  • nuts
  • meats
  • bread
  • dairy products
  • seaweed
  • iodized table salt

Iodine deficiency affects about 2 billion people worldwide. It’s most common in developing countries where people may lack access to enough healthy food. But it can also affect people in developed countries who lack an adequate diet or whose bodies don’t correctly process iodine.

Pregnant women require more iodine than any other group of people. Because of this, they’re likely to experience a deficiency if they don’t make a conscious effort to consume high-iodine foods.

Signs and symptoms of iodine deficiency include:

Swelling of the thyroid glands in the neck

This can cause a visible lump, called a goiter, to form on your neck.

Low levels of thyroid hormones (hypothyroidism)

Hypothyroidism typically causes symptoms that can include:

  • fatigue
  • increased sensitivity to cold
  • constipation
  • dry skin
  • weight gain
  • puffy face
  • muscle weakness
  • elevated blood cholesterol levels
  • pain or stiffness in the muscles and joints
  • slowed heart rate
  • thinning hair
  • depression
  • poor memory
  • a heavier-than-normal period in menstruating women

In infants, hypothyroidism is likely to cause symptoms like:

  • frequent choking
  • large tongue
  • puffy face
  • constipation
  • poor muscle tone
  • extreme sleepiness

In children and teens, this condition may cause:

  • poor growth
  • delayed tooth development
  • delayed puberty
  • poor mental development

Cognitive issues

Symptoms can include:

  • low IQ
  • trouble learning
  • mental disabilities (especially in children)

When left untreated, iodine deficiency can lead to severe hypothyroidism. Complications may include:

Low amounts of thyroid hormone in pregnant women can increase their child’s risk of birth defects. Pregnancy-related issues that iodine deficiency can cause include:

  • miscarriages
  • stillbirth
  • preterm delivery
  • congenital abnormalities in newborns

In severe cases, iodine deficiency can cause a condition called cretinism.

Myxedema is a rare but life-threatening complication of hypothyroidism that can be caused by iodine deficiency. Symptoms include:

  • an intense intolerance to cold temperatures
  • drowsiness followed by extreme fatigue, and ultimately, unconsciousness

In people with hypothyroidism, certain things can trigger a myxedema coma. These include sedatives, an infection, or other stressors on the body.

Myxedema is an emergency condition that requires immediate medical treatment. If you experience any of its symptoms, call 911 right away.

If your doctor suspects you have an iodine deficiency, they will usually check your iodine levels in one of four ways:

  • Urine test: This is the simplest and fastest test. You’re able to get results in minutes, but it’s not as accurate as some of the other iodine tests.
  • Blood test: This is a simple and accurate test for iodine levels in the body. However, it takes more time to read than a urine test.
  • Iodine patch test: The iodine patch test is a test where doctors paint a patch of iodine on your skin and check how it looks 24 hours later. For those who are not iodine deficient, the patch fades no sooner than 24 hours. But a deficiency will likely cause the iodine to be absorbed into the skin more quickly. This test is not the most accurate, but it’s inexpensive and relatively quick.
  • Iodine loading test: This test measures how much iodine you excrete in your urine over a 24-hour period. It’s not the fastest test; nor is it the most convenient. (You need to collect every urine sample you have in a 24-hour period.) But it’s quite accurate.

Iodine deficiency is best corrected by a healthy diet. If your diet alone is not supplying enough iodine, you may want to consider adding an iodine supplement. People who may not be getting enough iodine through food often include:

  • vegetarians
  • vegans
  • pregnant women

Keep reading: 16 delicious mushroom recipes for vegetarians »

Iodine supplements containing potassium are the most readily absorbed by the body. Look for supplements that contain potassium iodide and potassium iodate. Don’t take supplements in excess of 150 mcg per day. This could cause an iodine overload, which is also harmful to the thyroid.

Most people with iodine deficiency can fix their health issues by changing their diet and adding supplementation.

People with myxedema require hospitalization. At the hospital, doctors will administer intravenous fluids and other stabilizing treatments. They will also administer thyroid hormones to correct the condition. After a person with myxedema is stable, the doctor will monitor their thyroid function and determine if a change in diet to ensure they are consuming enough iodine will keep their hormone levels stable.

Read more: A healthy diet during pregnancy »

If caught early, iodine deficiency can be completely reversed with few to no side effects. However, if it’s caught after complications arise, many complications — especially in children — can be permanent. But even if complications have developed after iodine deficiency, making sure you get enough iodine going forward can prevent complications from getting worse.