Hashimoto's Disease

Overview

Hashimoto’s disease is a condition that causes inflammation and destruction of the thyroid gland (thyroiditis). Hashimoto’s disease is also known as chronic lymphocytic thyroiditis, or Hashimoto’s thyroiditis. This disorder is an example of an autoimmune disease, a type of disease in which the body’s immune system malfunctions and attacks itself. In Hashimoto’s disease, the immune system behaves abnormally and mounts an attack on the thyroid gland.

healthy thyroid glandThe thyroid gland is positioned in the anterior aspect of the neck and normally produces two hormones, triiodothyronine (T3) and thyroxine (T4). These hormones directly regulate or influence metabolism, body weight, heart rate, body temperature, breathing, nervous system functions, and muscle activity.

In Hashimoto’s disease, damage to the thyroid gland decreases thyroid hormone production. Often the diseased thyroid gland underperforms to such an extent that bodily functions are impaired, causing a disorder called hypothyroidism. Additionally, many individuals with severe thyroid gland inflammation develop a visible thyroid enlargement in the neck, termed a goiter.

Hashimoto’s disease is the most common type of thyroiditis. This condition occurs much more frequently in women than men and typically develops in people age 30 to 50.

Causes and Risk Factors

Normally the immune system makes proteins (antibodies) that protect the body against foreign invaders like viruses, bacteria, and cancers. In autoimmune diseases, such as Hashimoto’s disease, the immune system malfunctions and produces antibodies that mistakenly attack healthy tissues instead of protecting them. The exact trigger, causing the immune system to go awry, is unknown.

Risk factors for Hashimoto’s disease include the following:

  • Family history of thyroid disease
  • Having other autoimmune diseases (such as type 1 diabetes, lupus, or rheumatoid arthritis)
  • Excess consumption of iodine
  • Exposure to certain chemicals
  • Certain medications
  • Viral infections.

Symptoms of Hashimoto's Disease

The symptoms of Hashimoto’s disease are primarily those of hypothyroidism and enlargement of the thyroid gland (goiter) with pressure on adjacent structures in the neck. Hashimoto’s disease typically progresses very slowly, and often the symptoms are subtle or easily confused with other conditions. Some individuals with Hashimoto’s disease never develop hypothyroidism or goiter and experience no symptoms at all.

Hypothyroidism

Hakaru Hashimoto circa 1912Symptoms associated with hypothyroidism are as follows:

  • Fatigue
  • Sleepiness
  • Weight gain
  • Depression
  • Cold intolerance
  • Dry skin
  • Dry hair
  • Puffy face
  • Hoarseness
  • Leg swelling
  • Muscle aches
  • Heavy or irregular menstrual periods
  • Low heart rate
  • Constipation
  • Decreased concentration.

Myxedema

Severe untreated hypothyroidism leads to myxedema, a condition characterized by the following:

  • Heart failure
  • Seizures
  • Loss of consciousness
  • Death.

Goiter

Symptoms associated with goiter include:

  • Painless swelling of the thyroid gland in the front of the neck
  • Difficulty breathing
  • Difficulty swallowing.

Diagnosis and Treatment

An individual’s history and physical examination provide the initial basis for a diagnosis of thyroid disease. When a physician suspects hypothyroidism, specific blood tests confirm the diagnosis and identify the underlying disease.

Thyroid function tests

  • Thyroid-stimulating hormone level. When thyroid hormone levels are low, an area of the brain called the pituitary gland releases thyroid-stimulating hormone (TSH), a substance that stimulates the thyroid to produce more T4. An elevated TSH level is an early indicator of hypothyroidism.
  • Free T4. Free T4 is the amount of thyroid hormone available in the blood that body tissues use to support their activities. A low free T4 level is evidence of hypothyroidism.

Anti-thyroid antibody tests

Anti-thyroid antibodies distinguish Hashimoto’s disease from other causes of hypothyroidism. Hashimoto’s disease is identified by the presence of elevated levels of anti-thyroid antibodies not found in other forms of thyroid disease.

Imaging studies

Ultrasound imaging studies and computed tomography scans provide detailed pictures of the body. Physicians may use these studies to identify abnormal growths of the thyroid gland.

Treatment

Hypothyroidism is treated with a man-made thyroid hormone replacement medication called levothyroxine (Synthroid or Levoxyl). Although this medication does not reverse the thyroid gland damage, it effectively restores the bodily functions impacted by hypothyroidism. Physicians monitor TSH levels to determine the proper medication dosage for each individual.

Since the underlying problem is not cured, people with Hashimoto’s disease and hypothyroidism require life-long treatment with thyroid hormone replacement.

Prevention

Although there is no known way to prevent Hashimoto’s disease, the condition is highly treatable. Early treatment is recommended to avoid life-threatening problems associated with severe hypothyroidism.

Sources

  • Hashimoto’s Disease. National Endocrine and Metabolic Diseases Information Service (NEMDIS) website. http://www.endocrine.niddk.nih.gov/pubs/Hashimoto/. Accessed February 5, 2015.
  • Hashimoto’s disease. Mayo Clinic website. http://www.mayoclinic.org/diseases-conditions/hashimotos-disease/basics/definition/con-20030293. Accessed February 5, 2015.
  • Hashimoto’s Disease Fact Sheet. U.S. Department of Health and Human Services, Office on Women’s Health website. http://womenshealth.gov/publications/our-publications/fact-sheet/hashimoto-disease.html. Accessed February 5, 2015.