Thyroiditis is a general term for temporary inflammation of the thyroid which can be categorized into two groups.
Thyroid Function in Thyroiditis
Understanding thyroiditis requires good understanding of thyroid function testing. Most thyroiditis conditions are temporary and transient. They usually go through three predictable phases until resolution of the inflammation. This triphasic response is characterized by
Followed by normal thyroid function
Followed by hypothyroidism
Finally return to normal thyroid function.
The duration of all three phases may be as long as 6-12 months. There are two types of thyroiditis characterized by whether the thyroid gland itself is tender or not. Your endocrinologist at Houston Thyroid and Endocrine Specialists will guide you through the diagnostic challenges.
Painful Thyroid Gland
Subacute granulomatous thyroiditis: This group of disorders has multiple different names including, subacute thyroiditis, de Quervain's thyroiditis, and non-suppurative thyroiditis. This condition is thought to be caused by a viral infection or post viral inflammation. Yes subacute thyroiditis can be caused by COVID SARS COV-2 infection as a source of thyroiditis(1). Usually this condition follows a predictable triphasic response. Less than 5% of patients will be left with permanent hypothyroidism.
Infectious thyroiditis: This is usually a painful process. The infection usually is caused by direct extension into the thyroid from the skin or from bacterial infections that are carried to the thyroid from the blood. Patients are usually quite ill with fever. This is a rare condition.
Radiation thyroiditis: This is a painful condition that sometimes occurs after medical treatment with radioactive iodine from Graves disease. It usually occurs within 2 weeks of a treatment.
Palpation thyroiditis: Very deep massage or physical trauma (automobile seat bely) to the thyroid can cause a tender inflamed thyroid.
Painless Thyroid Gland
Painless thyroiditis: This is probably the most common type of thyroiditis. Hashimoto's thyroiditis is considered a variant of painless thyroiditis. This occurs in about 5% of cases of hyperthyroidism. These patents do not have the clinical appearance of Graves disease.
Post Partum thyroiditis: By definition this is a thyroiditis that occurs within one year after delivery of a child, whether spontaneous or induced abortion. This is a problem that This condition complicates about 10% of pregnancies and a small percentage of patients will develop permanent hypothyroidism.
Drug induced thyroiditis: Caused by interferon alpha, amiodarone, lithium, some tyrosine kinase inhibitors
The diagnosis of hyperthyroidism due to a thyroiditis can be accomplished with nuclear scanning of the thyroid. During the hyperthyroid phase the thyroid uptake is usually very low. The hypothyroid phase cannot generally be distinguished very easily from other causes of hypothyroidism. Treatment of the condition depends on the underlying cause.