Hashimoto's thyroiditis is a chronic (ongoing) condition where the body's immune system attacks the thyroid, a gland in the neck that makes thyroid hormone. More to Know The thyroid hormone helps the body handle many chemical reactions, controls how the body converts food into energy, and helps direct growth and sexual development. In someone with Hashimoto's, often the thyroid must work harder to make thyroid hormone. This, and the inflammation that occurs in the gland, can cause the thyroid to swell, resulting in a goiter. In some cases, the thyroid can't produce enough thyroid hormone. This is called hypothyroidism. Symptoms of hypothyroidism may include sluggishness, dry skin, feeling cold, constipation, facial puffiness, weight gain, and slowing of growth and sexual development. In rare cases, the immune system of someone with Hashimoto's thyroiditis can cause inflammation in the brain and nervous system. Symptoms can include strange behavior, confusion, muscle twitching, and seizures. Keep in Mind Hashimoto's thyroiditis is usually diagnosed by blood tests measuring the levels of thyroid hormone and the presence of antibodies. Hashimoto's is a chronic disorder, although the size of the thyroid and its ability to make thyroid hormone can increase or decrease over months and years. Treatment depends on symptoms and the results of lab tests. Hypothyroidism and goiters are usually treated with synthetic thyroid hormone taken in pill form. The treatment and dose of medication is guided by regular periodic blood tests and doctor visits. Surgery is sometimes done to treat goiters, especially if the thyroid becomes large enough to cause problems with swallowing. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles 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 Endocrine System The endocrine system influences almost every cell, organ, and function of our bodies. It is instrumental in regulating mood, growth and development, metabolism, and sexual function, among other things. Read More Endocrine System The glands of the endocrine system and the hormones they release affect almost every cell, organ, and function of our bodies. 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 What Are Glands? You've heard of glands, but what are they? Find out in this article for kids. Read More Word! Hormones Hormones are special chemicals your body makes to help it do certain things - like grow up! Read More Immune System The immune system is made up of special cells, proteins, tissues, and organs that defend people against germs and microorganisms. Read More Immune System The immune system, composed of special cells, proteins, tissues, and organs that protect against germs and microorganisms, is the body's defense against disease. Read More Your Immune System The immune system keeps you healthy. How does it work? Find out in this article for kids. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.