Hypothyroidism

Hyperthyroidism Slideshow Pictures Take the Thyroid Disorder Quiz Thyroid Symptoms and Solutions Slideshow Pictures

Medical Author:

Stephanie L Lee, MD, PhD, FACE

Coauthor:

Sonia Ananthakrishnan, MD

Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

View Full Profile

• Hypothyroidism Overview
• Hypothyroidism Causes in Adults
• Hypothyroidism Symptoms
• Hypothyroidism Diagnosis
• Hypothyroidism Treatment and Management
• Hypothyroidism Medications
• Hypothyroidism Follow-Up
• Related Health Complications of Hypothyroidism
• Synonyms and Keywords
• Authors and Editor
• Read more on Hypothyroidism from Healthwise
• Viewer Comments: Hypothyroidism - Treatments
• Viewer Comments: Hypothyroidism - Symptoms Experienced

Hypothyroidism Overview

Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormone. Thyroid hormones affect the metabolic processes of the body. Hypothyroidism can be caused by conditions of the thyroid as well as other disease which may indirectly affect the thyroid. Women are affected by hypothyroidism more than men, especially as they age. The incidence of hypothyroidism increases significantly in the elderly. Low thyroid hormone levels decrease metabolism (how energy is used), and increase the risk of other health issues such as heart disease and problems of pregnancy.

Hypothyroidism Causes in Adults

Common causes of hypothyroidism in adults include:

Autoimmune Thyroiditis (Hashimoto's Thyroiditis)

This inherited condition is the most common cause of hypothyroidism in adults. Hashimoto's thyroiditis is an autoimmune disease in which the body's immune system, or natural defense system, attacks its own thyroid gland. This causes a thyroid enlargement or goiter and progressive thyroid destruction.

Subacute Thyroiditis (inflammation of the thyroid gland after a viral disease or after a pregnancy)

In this condition there is usually a phase of hyperthyroidism (a condition in which the thyroid produces an excess of thyroid hormones) followed by a hypothyroid phase. Eventually thyroid function returns to normal. The three types of subacute thyroiditis are:

1. subacute granulomatous thyroiditis, also referred to as painful thyroiditis;
2. subacute painless thyroiditis, which is silent and also referred to as lymphocytic thyroiditis; and
3. postpartum thyroiditis.

Previous Thyroid Therapy

Surgical removal of the thyroid gland may be performed to treat thyroid nodules, hyperthyroidism, or other conditions. Treatment of hyperthyroidism with radioactive iodine also results in destruction of thyroid tissue and may lead to hypothyroidism.

Drug-induced Hypothyroidism

Taking some prescription medications may alter thyroid function. These include lithium (Eskalith, Lithobid) and amiodarone (Cordarone).

Pituitary and Hypothalamic disease

Both the hypothalamus and pituitary gland are involved in the signaling pathways that control the function of the thyroid gland. Diseases of the hypothalamus and pituitary gland can, therefore, affect the amount of thyroid hormone made and secreted by the thyroid gland. Hypothyroidism due to pituitary disease is termed "secondary hypothyroidism," while hypothyroidism due to hypothalamic disease is termed "tertiary hypothyroidism."

Iodine deficiency

Iodine deficiency does not occur in the U.S.. Only severe iodine deficiency will cause low thyroid hormone levels. This condition may occur in mountainous areas of poor, less industrialized nations. Mild to moderate iodine deficiency is common in many European countries.