Subacute thyroiditis (SAT) is a type of thyroid gland inflammation. It commonly leads to neck pain and symptoms that affect the body, such as fever and muscle pain. SAT is the most common, painful thyroid condition.

A 2022 research review, looking at current treatment methods, published in the International Journal of General Medicine is the source of the above information.

Other names for SAT are de Quervain thyroiditis and granulomatous thyroiditis. It predominantly affects females, comprising 75–80% of all cases, notes research.

The basis of a diagnosis involves symptoms that follow an upper respiratory tract inflammation. Treatment may include a nonsteroidal anti-inflammatory drug (NSAID) for pain and a corticosteroid for inflammation.

Keep reading to learn more about subacute thyroiditis, including causes, symptoms, diagnosis, treatment, and outlook.

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Researchers involved in a 2021 review of research consider a viral infection that people experienced 2–6 weeks prior as a triggering factor in those with a genetic predisposition for SAT. A complex of genes called human leukocyte antigens is linked to SAT susceptibility.

Possible viral causes include:

Other triggers include a class of medications called tumor necrosis factor (TNF) inhibitors, such as adalimumab (Abrilada, Humira).

Typically, the condition manifests with painful swelling of the thyroid gland. While sometimes the pain begins and is limited to one lobe, it usually spreads to the entire gland. The pain may radiate to the ear or jaw.

Common symptoms include:

  • a general feeling of discomfort
  • muscle pain
  • joint pain
  • mild to moderate fever, but at times, a high fever of 104°F

An additional symptom may involve temporary impaired movement of the vocal cords.

Also, approximately half of people have symptoms of thyrotoxicosis — high thyroid hormone levels — during the first week. The most common symptoms are the effects of excess thyroid hormones, such as weight loss and heat intolerance. Afterward, hypothyroidism — which is low thyroid hormone levels — occurs before the condition disappears.

Symptoms comprise the basis of a diagnosis. Usually, this involves pain in the front of the neck following recent upper respiratory tract inflammation.

Other diagnostic tools include:

Thyroid function tests

These tests measure thyroid hormone levels in the blood. During the painful phase of the disease, the tests frequently reveal lower levels of thyroid stimulating hormone (TSH). The pituitary gland in the brain produces TSH to regulate thyroid hormones.

The painful phase also involves higher levels of the other thyroid hormones, including triiodothyronine (T3) and thyroxine (T4).

Learn more about TSH.

Radioactive iodine uptake

This test shows thyroid functioning because it measures the amount of radioactive iodine the thyroid gland absorbs.

Usually, more-than-normal uptake indicates high thyroid activity, while less-than-normal uptake denotes low thyroid activity.

Ultrasound

This type of imaging is the most common scan for thyroid gland evaluation.

Learn more about thyroid ultrasound.

The aforementioned 2022 review states that treatment goals include reducing pain with minimal side effects and decreasing the likelihood of relapse and permanent hypothyroidism.

For some people, no treatment is necessary. Treatments in mild to moderate cases involve NSAIDs, such as ibuprofen (Motrin, Advil).

In more severe cases, treatment involves corticosteroids, such as prednisolone (Orapred).

The prednisolone dosage is 20–40 milligrams per day for 2 weeks. Afterward, a doctor will gradually reduce the dosage over 6 weeks. In most individuals with SAT, the symptoms do not recur. However, in 20% of people, symptoms recur, in which case, the dosage increases again.

Other treatments include:

  • Beta-blockers: These are typical treatments for thyrotoxic symptoms — such as fast heart rate — in the initial stage of SAT. An example is propranolol (Hemangeol, Inderal).
  • Oral cholecystographic agents: These agents help treat high levels of thyroid hormones. An example is barium sulfate (Bar-Test).
  • Levothyroxine: This is a thyroid hormone used to treat hypothyroidism. Synthroid and Levoxyl are two levothyroxine brand-name medications.
  • Surgery: This is not the primary treatment for SAT, but if a doctor suspects the possibility of associated cancer, they may deem it necessary.

SAT may peak in 3–4 days and disappear within a week. However, more often, the onset occurs over 1–2 weeks and continues for 3–6 weeks with intensity that fluctuates up and down.

The outlook is usually good, as 90% or more of people recover completely and return to typical thyroid function. This happens within 12–18 months.

That said, some individuals have irregular scarring of the thyroid gland. Up to 10% experience hypothyroidism, where permanent thyroid hormone replacement is necessary.

Subacute thyroiditis is thyroid gland inflammation that manifests with pain in the front of the neck, along with fever, muscle pain, and joint pain. Researchers believe a virus is the cause.

The primary diagnostic indicator involves symptoms following a recent upper respiratory tract inflammation. Additionally, doctors may use thyroid function tests, a radioactive iodine test, and an ultrasound to confirm a diagnosis.

Treatment may include an NSAID for pain, along with a 6-week course of a corticosteroid for inflammation.

Other medication options may include beta-blockers, oral cholecystographic agents, and thyroid hormone replacement. Treatment can help a person feel more comfortable, so experts recommend that anyone with symptoms see a doctor.

The duration of SAT can vary from a few days to 3–6 weeks. The outlook is good because 90% of or more people recover completely within 12–18 months.