Silent thyroiditis is inflammation of the thyroid gland that involves alternating hyperthyroidism and hypothyroidism followed by recovery.

Lymphocytic thyroiditis; Subacute lymphocytic thyroiditis; Painless thyroiditis

The cause of this type of thyroiditis is unknown. The disease affects women more often than men and usually develops in people between age 13 and 80.

The initial symptoms are those of hyperthyroidism (overactivity of the thyroid gland), and may last for 3 months or less. Later symptoms may be more characteristic of an underactive thyroid (including fatigue, cold intolerance) until the thyroid recovers.

Symptoms are usually mild and may include:

• Fatigue
• Frequent bowel movements
• Heat intolerance
• Increased appetite
• Increased sweating
• Irritability
• Muscle cramps
• Menstrual irregularities
• Nervousness, restlessness
• Palpitations
• Weakness
• Weight loss

A physical examination reveals an enlarged thyroid gland. The heart rate may be rapid and the hands may shake.

Tests may show that radioactive iodine uptake is decreased and blood levels of the thyroid hormones T3 and T4 are increased.

A thyroid biopsy shows lymphocytes (a type of white blood cells) in the gland.

Treatment is based on symptoms. Beta-blockers relieve rapid heart rate and excessive sweating.

Generally, silent thyroiditis will go away on its own within 1 year, with the acute phase ending in 3 months. Some people may develop hypothyroidism over time, so regular follow ups with a doctor are recommended.

Hypothyroidism may develop.

Call your health care provider if you have symptoms of this condition.

AACE Thyroid Task Force. American Association of Clinical Endocrinologists Medical Guidelines for Clinical Practice for the Evaluation and Treatment of Hyperthyroidism and Hypothyroidism. Endocr Pract. 2002;8(6) 459.