Subacute thyroiditis is acute inflammation of the thyroid, probably caused by a virus.
(See also Overview of the Thyroid Gland.)
Subacute thyroiditis usually begins suddenly. In this disorder, inflammation causes the thyroid gland to release excessive amounts of thyroid hormones, resulting in hyperthyroidism, almost always followed by transient hypothyroidism and finally normal thyroid function.
Symptoms of Subacute Thyroiditis
Subacute thyroiditis often follows a viral illness and begins with what many people call a sore throat but actually proves to be neck pain localized to the thyroid. The thyroid gland becomes increasingly tender. The pain may shift from one side of the neck to the other, spread to the jaw and ears, and hurt more when the head is turned or when the person swallows. Subacute thyroiditis is often mistaken at first for a dental problem or a throat or ear infection.
Many people with subacute thyroiditis feel extremely tired. The person usually develops a low-grade fever (99 to 101° F [37 to 38º C]).
People with subacute thyroiditis may at first have symptoms of hyperthyroidism, such as increased heart rate and blood pressure, excessive sweating and feeling too warm, hand tremors (shakiness), and nervousness and anxiety, and later develop symptoms of hypothyroidism, including fatigue, weight gain, constipation, dry skin and hair, and cold intolerance.
Diagnosis of Subacute Thyroiditis
Thyroid function blood tests
Radioiodine thyroid scan and uptake
The diagnosis of subacute thyroiditis is made based on a person's symptoms and the results of the examination and thyroid function blood tests.
Sometimes, it may be difficult to differentiate subacute thyroiditis from Graves disease, in which case doctors do a thyroid scan and uptake test. Because of the inflammation, little or no radioactivity is taken up by the thyroid gland in subacute thyroiditis while uptake is increased in Graves disease.
Thyroid ultrasonography can also help diagnose subacute thyroiditis.
Treatment of Subacute Thyroiditis
Sometimes medications to relieve pain and inflammation
Most people recover completely from this type of thyroiditis. Generally the thyroiditis resolves by itself within a few months, but sometimes it comes back or, more rarely, damages enough of the thyroid gland to cause permanent hypothyroidism.
When symptoms of hyperthyroidism are severe, a beta-blocker may be recommended.
