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Hashimoto's Thyroiditis

Hashimoto's thyroiditis is an autoimmune disease in which the immune system attacks the thyroid gland. It is the most common cause of hypothyroidism in the U.S. and is readily treated with thyroid hormone.

Endocrine
Hashimoto's thyroiditis is an autoimmune condition in which the immune system mistakenly attacks the thyroid gland, causing chronic inflammation that slowly reduces the gland's ability to make thyroid hormone. It is the most common cause of an underactive thyroid (hypothyroidism) in the United States. Women are affected far more often than men, and the condition most commonly appears in middle age, though it can occur at any point in life. The disease progresses slowly, and many people have laboratory changes years before they feel unwell. Causes and Risk Factors: Why the immune system turns against the thyroid is not fully understood, but several factors raise the risk:
  • Family history: Thyroid and other autoimmune diseases cluster strongly in families.
  • Sex and age: Women, particularly in middle age, are affected most often.
  • Other autoimmune conditions: People with type 1 diabetes, celiac disease, rheumatoid arthritis, or vitiligo are more likely to develop Hashimoto's.
  • Pregnancy: Thyroid inflammation sometimes first appears in the year after delivery.
Symptoms: Symptoms develop gradually, often over years, as hormone levels fall — and early on there may be none at all. Common symptoms include:
  • Fatigue and sluggishness: Often the first and most persistent complaint.
  • Cold intolerance: Feeling cold when others are comfortable.
  • Weight gain: Usually modest, from a slowed metabolism and fluid retention.
  • Dry skin, hair thinning, and brittle nails: Reflecting slowed cell turnover.
  • Constipation, muscle aches, and joint stiffness: The digestive tract and muscles slow down too.
  • Depressed mood, poor memory, heavy menstrual periods, and an enlarged thyroid (goiter): All can accompany low thyroid hormone.
  • A feeling of fullness in the throat: From gland enlargement, though the thyroid can also shrink over time as the disease progresses.
Diagnosis: Diagnosis is straightforward with blood tests. An elevated thyroid-stimulating hormone (TSH) with a low free thyroxine (T4) confirms hypothyroidism, and antibodies against thyroid peroxidase (TPO) point to Hashimoto's as the cause. Some people have positive antibodies with normal hormone levels; they need periodic monitoring, since hypothyroidism can develop later. Because symptoms overlap with many other conditions — menopause, depression, anemia — blood testing is the only reliable way to know. Untreated hypothyroidism also commonly raises cholesterol, so lipid testing (high cholesterol) is often part of the picture. Treatment: Treatment is simple, safe, and highly effective:
  • Levothyroxine: A once-daily tablet of synthetic thyroid hormone replaces what the gland can no longer make. It is best taken on an empty stomach, separated from calcium, iron, and antacids, which block its absorption.
  • Dose monitoring: TSH is rechecked about six to eight weeks after any dose change, then once or twice a year once stable.
  • Lifelong follow-up: The gland's function usually continues to decline slowly, so doses may need adjustment over the years, and requirements change in pregnancy.
  • What to avoid: Over-the-counter "thyroid support" products and iodine supplements are not effective treatments, and excess iodine can actually worsen Hashimoto's.
Complications: Untreated hypothyroidism can lead to a persistently enlarged goiter, worsening cholesterol and heart disease risk, a slowed heart rate, infertility, and problems in pregnancy for both mother and baby. In rare, severe cases, profound hypothyroidism causes myxedema — extreme sleepiness, low body temperature, and confusion — a medical emergency. These outcomes are almost entirely preventable with treatment. With the right dose of levothyroxine, people with Hashimoto's thyroiditis feel well and live completely normal lives. The internal-medicine team at Zimmer Medical Group manages thyroid disease from diagnosis through long-term monitoring — schedule a visit if you have symptoms of an underactive thyroid.

Related Medications

Commonly prescribed medications for this condition

Levothyroxine

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