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Iodine deficiency symptoms: What are the early signs of iodine deficiency?

Medically reviewed by Leslie Greenberg, MD
Board-Certified Family Physician
Updated Oct. 27, 2023  •  Published Sep. 15, 2023
Fact Checked
Iodine deficiency symptoms: What are the early signs of iodine deficiency?

Overview: What does iodine deficiency feel like?

Although the body needs only a tiny bit of iodine daily, about 3/100 teaspoon is a micronutrient vital to every body part. Without iodine, the body can’t make thyroid hormones. Thyroid hormones keep us alive. They regulate energy use, generate growth, maintain a constant body temperature, and are critical in breaking down sugars, fats, and proteins for energy. The only place people get iodine is in their diet. If they get too little dietary iodine intake, the thyroid gland does not produce enough thyroid hormones. With hypothyroidism, every part of the body is affected. Often, the first sign is swelling of the thyroid gland at the front of the neck. Later symptoms include symptoms of hypothyroidism. Many processes in the body slow down. People feel tired, weak, and have low energy. They gain weight. They feel cold. The heart slows down. Thinking, concentrating, and staying alert becomes harder. 

RELATED: Hypothyroidism vs. hyperthyroidism: compare causes, symptoms, treatments & more

Key takeaways:

  • Iodine deficiency is a rare health condition in the U.S. that can affect anyone regardless of age, sex, race, or ethnicity. 

  • Early signs of iodine deficiency include thyroid gland enlargement (goiter) or mild hypothyroidism symptoms.

  • Serious symptoms of iodine deficiency, such as confusion, disorientation, slow breathing, a slow heart rate, low blood pressure, hypothermia, or coma, may require immediate medical attention.

  • Iodine deficiency is caused by low levels of iodine in the diet. You may be at risk of developing iodine deficiency symptoms if you do not eat iodized salt, don’t eat fish or dairy, live far from the sea, or are pregnant or lactating.

  • Iodine deficiency usually requires a medical diagnosis.

  • Iodine deficiency generally requires treatment. Iodine deficiency symptoms typically resolve with treatment within a few months.

  • Treatment of iodine deficiency may include dietary changes, supplements, and thyroid hormone treatment. 

  • Untreated iodine deficiency could result in complications like hypothyroidism, severe hypothyroidism, myxedema coma, pregnancy problems, birth defects, cretinism, stunted growth, developmental delays, deafness, or permanent intellectual disabilities.

  • Use coupons for iodine deficiency treatments like kelp supplements to save up to 80%.

What are the early signs of iodine deficiency?

The earliest sign of iodine deficiency is typically swelling of the thyroid gland, a butterfly-shaped gland at the front of the neck. Swelling of the thyroid glad is called a goiter. Symptoms might include:

  • Nodules or bumps on the thyroid gland

  • Visible swelling at the front of the neck

  • Difficulty swallowing

  • Difficulty breathing

Not everyone with mild cases will have an enlarged thyroid but they can have mild symptoms of low thyroid hormone, such as:

  • Feeling tired much of the time

  • Getting worn out easily

  • Sensitivity to cold

  • Feeling depressed or blue

  • Problems with concentrating or thinking

RELATED: Symptoms of thyroid problems: what are the early signs of thyroid disorders?

Other iodine deficiency symptoms

Iodine deficiency can cause two symptoms: goiter (enlarged thyroid) and hypothyroidism (low thyroid hormone levels).

A goiter is a swollen thyroid gland. The thyroid swells when thyroid hormone production is blocked in some way. In response, the pituitary gland overproduces thyroid stimulating hormone (TSH) to prod the thyroid gland into making more thyroid hormone. This works for a while, but after a few months, the excess TSH causes the thyroid gland to enlarge. Symptoms of goiter include:

  • Nodules that can be felt on the thyroid gland

  • Swelling or a lump at the front of the neck

  • Trouble swallowing

  • Difficulty breathing

  • Choking sensation

Low thyroid hormone causes problems throughout the body. The most common symptoms of hypothyroidism include:

  • Decreased energy levels

  • Fatigue

  • Depression 

  • Slow reflexes

  • Slow heart rate

  • Weakened pulse

  • Cold intolerance

  • Unexpected weight gain

  • Facial swelling

  • Dry skin

  • Hair loss

  • Constipation

  • Hoarse voice

  • Muscle weakness

  • Muscle aches

  • Menstrual irregularities: heavy periods, irregular periods, loss of periods

Iodine deficiency vs. hypothyroidism symptoms

Iodine deficiency causes hypothyroidism, or an underactive thyroid, along with hypothyroidism symptoms. The symptoms, then, are identical. However, hypothyroidism has many causes other than iodine deficiency. Some of these causes may have other symptoms, including thyroid enlargement and low thyroid hormone symptoms.

RELATED: Hypothyroidism treatments and medications

Types of iodine deficiency: How can I tell which one I have?

Healthcare professionals typically distinguish between four types of iodine deficiency based on the person affected. While these all have the same symptoms, the complications are more serious for some people.

  • Iodine deficiency in pregnant women is considered the riskiest type of iodine deficiency. Pregnant women need higher iodine levels in their diet. Severe iodine deficiency can result in complications impacting the mother during pregnancy including miscarriage or fetal death. It can also causefetal complications such as birth defects, deafness, dwarfism, and cretinism (lifelong mental disability and short stature). 

  • Neonate iodine deficiency describes babies born with low iodine. The deficiency puts newborns at risk for goiter, hypothyroidism, developmental impairments, and cognitive disabilities. In the U.S., all newborns are tested for thyroid hormone at one day of age before they leave the hospital because of the risks.

  • Children with iodine deficiency are at risk of goiter, subclinical hypothyroidism, poor mental function, poor school performance, delayed development, and stunted growth. Iodine deficiency in babies and younger children can permanently affect brain development. 

  • Adults with iodine deficiency are at risk for goiter, hypothyroidism, and fertility problems. 

When to see a doctor for iodine deficiency symptoms

See a doctor or other healthcare provider if the thyroid is swollen or you experience symptoms of hypothyroidism. It may be something other than an iodine deficiency, but thyroid problems are usually easily corrected.

To diagnose iodine deficiency, healthcare providers examine the neck, perform a physical exam, and take a medical history. A clinician may also administer a blood test to measure TSH levels. If those levels are high, the clinician will measure thyroid hormone levels and test for antibodies. If the problem is iodine deficiency, urine tests are the usual way clinicians measure iodine in the body. 

Complications of iodine deficiency

For adults, the complications of untreated iodine deficiency may include:

In pregnant women, untreated iodine deficiency may cause problems with the pregnancy or the fetus, including:

  • Miscarriage

  • Stillbirth

  • Death of the baby shortly after birth

  • Birth defects

  • Cretinism (cognitive disabilities and short stature)

In newborns, untreated iodine deficiency may cause serious complications such as:

  • Goiter

  • Hypothyroidism

  • Intellectual disability

  • Developmental disabilities

In children, untreated iodine deficiency may cause complications such as:

  • Goiter

  • Subclinical hypothyroidism

  • Stunted growth

  • Learning difficulties

How to treat iodine deficiency symptoms

The only way to remedy iodine deficiency is to increase dietary iodine. This can be done with iodine-rich foods, iodine supplements, multivitamins with iodine, prenatal vitamins with iodine, kelp powder, or the aid of a dietitian.

In rare cases, a doctor may prescribe thyroid hormone replacement, usually levothyroxine, a synthetic form of thyroid hormone. 

Signs iodine deficiency is getting better

Iodine supplements typically improve iodine deficiency symptoms in one to three months. Both iodine and thyroid hormone levels normalize by that time. Symptoms gradually improve while taking additional iodine, but some people may take too much iodine and experience symptoms of overactive thyroid.

Most importantly, consume enough iodine daily to prevent iodine deficiency

Iodine deficiency is directly related to a person’s dietary intake of iodine. Adults should ingest about 150 micrograms (mcg) of iodine. Pregnant women should get 220 mcg per day. Women who are breastfeeding should get 290 mcg daily.

Ultimately, iodine comes from rocks and soil but is concentrated in the ocean and animals. The best sources of iodine are saltwater fish, seafood, seaweed, meat, dairy products, and eggs, but anything made with iodized salt is good. Though good for you in many other ways, vegetables have little iodine.

Here’s a list of the best dietary sources for iodine:

  • Bread made with iodate dough conditioner (sodium iodate)

Two slices provide 200% of the adult recommended daily allowance

  • Powdered kelp

One gram of powdered kelp provides 130% of the adult RDA

  • Cod

Three ounces of baked cod provides 100% of the RDA

  • Seaweed

Two tablespoons of flaked dried seaweed = 77% 

  • Greek yogurt

Three-fourths of a cup of plain, nonfat Greek yogurt = 58% 

  • Milk

One cup of nonfat milk = 57% of the recommended ADA

  • Iodized table salt

One-fourth teaspoon of iodized table salt = 50%

  • Other good sources of iodine include:

Fish sticks

Eggs

Tuna

Shrimp

Cheese

Dietary supplements can also help. It’s not uncommon for multivitamins to have a full day’s allowance of iodine. Some prenatal vitamins also contain iodine. Check the package’s list of ingredients to be sure. These vitamins will contain either potassium iodide or sodium iodide. The body better absorbs potassium iodide. 

RELATED: How to treat iodine deficiency with diet and supplements

FAQs about iodine deficiency symptoms

What disease causes iodine deficiency?

Iodine deficiency is caused by insufficient iodine in the diet. It’s common in developing countries, but it’s rare in places like the United States, where iodine is routinely added to salt and found in many packaged foods.

Is anxiety a symptom of iodine deficiency?

Iodine deficiency causes hypothyroidism, which affects thyroid function. Low thyroid hormones cause the body to slow down, so depression is a common symptom. However, anxiety symptoms are also commonly experienced by people with an underactive thyroid. 

What is the best indicator of iodine deficiency?

The symptoms of iodine deficiency are identical to those of hypothyroidism. But hypothyroidism has other causes besides iodine deficiency, including autoimmune diseases—the most common cause of hypothyroidism—thyroid cancer, and medication side effects. The only way to discover if the problem is iodine deficiency is to measure iodine in the body. That’s hard to do because most of it is in the thyroid gland. The easiest way to measure iodine is to measure the amount of iodine in the urine.

What’s next? Additional resources for people with iodine deficiency symptoms

Test and diagnostics

Treatments

Scientific studies and clinical trials

Medically reviewed by Leslie Greenberg, MD
Board-Certified Family Physician

Leslie Greenberg, MD, is a board-certified practicing family physician with more than 25 years of doctoring experience. She was a psychology major at Northwestern University near Chicago, then graduated with an MD from the University of Nevada School of Medicine. She completed her family medicine residency at St. Joseph Hospital in Wichita, Kansas. She has trained more than 350 family medicine resident-physicians, been in private practice, and delivered babies for 22 years.

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