What Is the Thyroid?

The thyroid is a small gland below the skin and muscles at the front of the neck, at the spot where a bow tie would rest.

It's brownish red, with left and right halves (called lobes) that look like a butterfly's wings. It weighs less than an ounce, but helps the body do many things, such as get energy from food, grow, and go through sexual development. In younger children, it is also important for brain development.

What Is Hypothyroidism?

Hypothyroidism (or underactive thyroid) is when the thyroid gland doesn't make enough of some important hormones. This makes the body use up energy more slowly, and chemical activity (metabolism) in the cells slows down.

Hypothyroidism is a common condition, especially in adult women. But kids can have it too. Some children are born with it — this is called congenital hypothyroidism. Others develop it later, usually late in childhood or as teens. The most common cause of hypothyroidism in kids and teens is the autoimmune disease Hashimoto's thyroiditis.

A view of the thyroid, a gland below the skin and muscles at the front of the neck, as described in the article.

What Are the Signs & Symptoms of Hypothyroidism?

A person with mild hypothyroidism may feel just fine. In fact, it might cause no symptoms at all.

But if thyroid hormone levels get too low, symptoms can become more obvious. These include:

  • sluggishness
  • depression
  • dry skin or hair loss
  • feeling cold
  • muscle weakness
  • poor memory or trouble concentrating
  • constipation
  • facial puffiness 
  • weight gain (even when not eating more or exercising less)
  • slowed growth
  • slow sexual development
  • irregular menstrual periods in girls

What Is Hashimoto's Thyroiditis?

Hashimoto's thyroiditis (hah-she-MOE-toes thy-roy-DYE-tiss) is an autoimmune disease. It causes most cases of hypothyroidism in kids and teens. Hashimoto's thyroiditis is also called chronic lymphocytic thyroiditis.

What Happens in Hashimoto's Thyroiditis?

Hashimoto's thyroiditis is an ongoing condition in which the immune system attacks the thyroid. Often, this prevents the thyroid from making enough thyroid hormone, causing hypothyroidism. The body responds by sending a message to the thyroid to work harder to make enough hormone.

This, and the swelling the immune system causes as it attacks the gland, can make the thyroid get bigger, leading to a goiter. The thyroid can keep changing size over months or years. Surgery is sometimes done to treat goiters, especially if the thyroid is big enough to cause problems with swallowing. But this is rarely needed in children.

How Are Hypothyroidism and Hashimoto's Thyroiditis Diagnosed?

To diagnose hypothyroidism and Hashimoto's thyroiditis, doctors ask about a person's symptoms, do an exam, and order blood tests. The tests measure:

  • Thyroid hormone levels, particularly thyroxine (T4) and thyroid-stimulating hormone (TSH). TSH is a hormone made in the pituitary gland (a pea-sized gland just beneath the brain). More TSH is released into the blood when the brain and pituitary sense that the levels of thyroid hormone in the blood are too low. TSH stimulates the thyroid to work harder to make more thyroid hormone.
  • Some antibodies (proteins made by the immune system). High levels of these antibodies in the blood are a sign that the gland is being attack by the immune system in Hashimoto's. The two antibodies commonly measured are thyroglobulin antibodies (TgAb) and thyroid peroxidase antibodies (TPO).

How Are Hypothyroidism and Hashimoto's Thyroiditis Treated?

Doctors treat an underactive thyroid with daily thyroid hormone replacement pills. These will bring the body's levels of thyroid hormone back to normal.

This treatment is fairly simple, but a person will have doctor visits several times a year for an exam, blood tests, and medicine changes as needed.

What Else Should I Know?

In rare cases, the immune system of a child with Hashimoto's can cause inflammation in the brain and nervous system. Symptoms can include strange behavior, confusion, muscle twitching, and seizures.

Back to Articles


Related Articles

Thyroid Disease

The thyroid gland makes the hormones that help control metabolism and growth. A thyroid that isn't working properly can cause thyroid disease.

Read More

What Is the Thyroid?

Do you know just how important the thyroid is? It helps you grow and affects your energy level.

Read More

Thyroid Tests

Thyroid blood tests check thyroid function and can help doctors diagnose thyroid disorders such as hypothyroidism and hyperthyroidism.

Read More

Hyperthyroidism and Graves’ Disease

Hyperthyroidism happens when the thyroid gland sends too much thyroid hormone into the blood. The most common cause of hyperthyroidism is Graves' disease.

Read More

Goiters and Thyroid Nodules

An enlarged thyroid gland is a lump that can be felt under the skin at the front of the neck. When it's big enough to see easily, it's called a goiter. A thyroid nodule is a lump or enlarged area in the thyroid gland.

Read More

Congenital Hypothyroidism

Some babies are born with a thyroid gland that didn't develop correctly or doesn't work as it should. This is called congenital hypothyroidism.

Read More

Blood Test: T3 Resin Uptake (T3RU)

Doctors may order the T3 resin uptake when a child's symptoms or previous blood tests seem to suggest thyroid dysfunction.

Read More

Blood Test: T4 (Thyroxine)

Doctors may order the T4 blood test if symptoms suggest any kind of thyroid disorder.

Read More

Blood Test: Thyroid Peroxidase Antibodies

The thyroid peroxidase antibodies test is primarily used to help diagnose and monitor autoimmune conditions involving the thyroid gland, including Hashimoto's thyroiditis and Graves disease.

Read More

Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2020 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.

Search our entire site.