What is thyroiditis?
Thyroiditis includes a group of individual disorders that all cause thyroidal inflammation. As a result, there may be many different clinical presentations, from hypothyroidism to an enlarged thyroid (Goiter) to symptoms similar to hyperthyroidism.

CAUSES

What causes thyroiditis?
Thyroiditis is caused by an attack on the thyroid, causing inflammation and damage to the thyroid cells. Antibodies that attack the thyroid cause most types of thyroiditis. Thyroiditis can also be caused by an infection, such as a virus or bacteria, or certain drugs

What are the clinical symptoms of thyroiditis?
There are no symptoms unique to thyroiditis. If the thyroiditis causes slow and chronic thyroid cell damage and destruction, leading to a fall in thyroid hormone levels in the blood, the symptoms would be those of hypothyroidism (see Hypothyroidism brochure). If the thyroiditis causes rapid thyroid cell damage and destruction, the thyroid hormone that is stored in the gland leaks out, increasing thyroid hormone levels in the blood, and produces symptoms of thyrotoxicosis, which are similar to hyperthyroidism (see Hyperthyroidism brochure). Pain in the thyroid can be seen in patients with subacute thyroiditis.

What are the types and clinical course of thyroiditis?

Hashimoto’s thyroiditis – Patients usually present with hypothyroidism, which is usually permanent.

Subacute, painless and post-partum thyroiditis – These disorders follow the same general clinical course of thyrotoxicosis followed by hypothyroidism. The thyrotoxic phase usually lasts for 1-3 months and is associated with symptoms including anxiety, insomnia, palpitations (fast heart rate), fatigue, weight loss, and irritability. Thyroidal pain in subacute thyroiditis follows the thyrotoxic phase. The hypothyroid phase typically occurs 1-3 months after the thyrotoxic phase and may last up to 9 –12 months. Typical symptoms include fatigue, weight gain, constipation, dry skin, depression and poor exercise tolerance. Most patients (80-95%) will have return of their thyroid function to normal within 12-18 months of the onset of symptoms.

Drug-induced and radiation thyroiditis – Both thyrotoxicosis and hypothyroidism may be seen. The thyrotoxicosis is usually short-lived. Drug-induced hypothyroidism often resolves with the cessation of the drug, while the hypothyroidism related to radiation thyroiditis is usually permanent.

Acute/Infectious thyroiditis – Symptoms range from thyroidal pain, systemic illness, painless enlargement of the thyroid and hypothyroidism. The symptoms usually resolve once the infection resolves.