Silent thyroiditis is swelling (inflammation) of the thyroid gland, in which the person alternates between hyperthyroidism and hypothyroidism.

The cause of this type of thyroiditis is unknown. The disease affects women more often than men. It usually develops in people ages 13 - 80.

The earliest symptoms are those of overactive thyroid gland (hyperthyroidism). These symptoms may last for 3 months or fewer. Later symptoms may be of an underactive thyroid (including fatigue and cold intolerance) until the thyroid recovers.

Symptoms are usually mild and may include:

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

A physical examination may show:

• Enlarged thyroid gland
• Rapid heart rate
• Shaking hands

Tests may show:

• Decreased radioactive iodine uptake
• Increased blood levels of the thyroid hormones T3 and T4
• White blood cells (lymphocytes) on a thyroid biopsy

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. The acute phase will end within 3 months.

Some people may develop hypothyroidism over time. 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;8:459.

Ladenson P, Kim M. Thyroid. In: Goldman L and Ausiello D, eds. Goldman: Cecil Medicine. 23rd ed. Philadelphia, Pa:Saunders;2007:chap 244.