What is subacute thyroiditis?
Thyroiditis refers to the inflammation of the thyroid. The thyroid is a gland in the front of the neck that releases a variety of hormones. These hormones help regulate metabolism, the process that converts food into energy. They also play a crucial role in your physical and emotional responses, such as fear, excitement, and pleasure.
Thyroiditis includes a group of disorders that cause the thyroid to become inflamed. Most types of thyroiditis typically lead to either hyperthyroidism or hypothyroidism. Hyperthyroidism is a disorder in which the thyroid is overactive and produces too much hormones. Hypothyroidism is a condition in which the thyroid is underactive and doesn’t make enough hormones. Both of these conditions can cause weight changes, anxiety, and fatigue.
Subacute thyroiditis is a rare type of thyroiditis that causes pain and discomfort in the thyroid. People with this condition will also have symptoms of hyperthyroidism and later develop symptoms of hypothyroidism. While often temporary, subacute thyroiditis can cause permanent complications if left untreated.
Unlike other forms of thyroiditis, subacute thyroiditis is thought to be linked to a viral infection. In response to the virus, the thyroid swells and can disrupt hormone production. This causes inflammation and a variety of symptoms.
Unlike other forms of thyroiditis, subacute thyroiditis causes pain in the thyroid gland. In some cases, this pain might also spread to other parts of your neck, ears, or jaw. Your thyroid may be swollen and tender to the touch. The American Thyroid Association estimates that the pain commonly lasts between 1 and 3 months.
Other symptoms of subacute thyroiditis include:
- difficulty swallowing
Most people typically develop hyperthyroidism in the initial stages of subacute thyroiditis. The symptoms during this stage of the disease may include:
- trouble concentrating
- sudden weight loss
- fast or irregular heartbeat
- increased body temperature that often leads to excessive sweating
As the disease progresses, hypothyroidism generally replaces hyperthyroidism in the second stage. The symptoms during the second stage may include:
- hair loss
- cold intolerance
- sudden weight gain
- heavy menstrual periods
The first stage of subacute thyroiditis usually lasts for less than three months. The second stage may last for an additional nine to 15 months.
There are four different subtypes of subacute thyroiditis:
Subacute granulomatous thyroiditis: Thisis the most common type of subacute thyroiditis. It’s mostly caused by viral infections.
Postpartum thyroiditis: This occurs in women within one year after giving birth, and usually goes away within 18 months. Women who develop this form of thyroiditis are thought to have an underlying autoimmune disease that causes the inflammation. Symptoms occur in two phases, starting with hyperthyroid symptoms and moving to hypothyroid symptoms.
Subacute lymphocytic thyroiditis: This also occurs during the postpartum period. Hyperthyroid symptoms develop earlier (usually within three months after giving birth), and hypothyroid symptoms can last for several months after.
Palpation thyroiditis: This develops when thyroid follicles are damaged from mechanical manipulation such as repeated examination of the thyroid gland or surgery.
All of the subtypes of subacute thyroiditis follow a similar course of symptoms, with hyperthyroid developing first. The key differences are the causes.
Your doctor will feel and examine your neck to see if the thyroid gland is enlarged or inflamed. They’ll also ask you about your symptoms and your recent medical history. Your doctor will be more likely to check for subacute thyroiditis if you’ve recently had a viral infection in the upper respiratory tract.
Your doctor will order a blood test to confirm a subacute thyroiditis diagnosis. This test will check the levels of certain hormones in your blood. Specifically, the blood test will measure your thyroid hormone, or free T4, and thyroid stimulating hormone (TSH) levels. The free T4 and TSH levels are part of what’s called an “internal feedback loop.” When one level is high, the other level is low, and vice versa.
The results of the blood test will vary depending on the stage of the disease. In the initial stages, your free T4 levels will be high while your TSH levels will be low. In the later stages, your TSH levels will be high while your T4 levels will be low. An abnormal level of either hormone indicates subacute thyroiditis.
If you’re diagnosed with subacute thyroiditis, your doctor will give you medications to help reduce the pain and control inflammation. In some cases, this is the only treatment required for subacute thyroiditis. Possible medications include:
- Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs). Medications like aspirin and ibuprofen work by reducing inflammation. As a result, you will experience less pain. Acetaminophen (Tylenol) is not as effective because it doesn’t reduce the inflammation thyroiditis causes.
- Corticosteroids. Corticosteroids are used when NSAIDs aren’t enough to reduce swelling. Prednisone is a common corticosteroid used to treat subacute thyroiditis. Your doctor may prescribe 15 to 30 milligrams per day to start, and then slowly decrease the dosage over three to four weeks.
- Beta-blockers. Your doctor may prescribe beta-blockers if hyperthyroidism is present in the early stages. These medications lower blood pressure and pulse rate to relieve certain symptoms, including anxiety and an irregular heartbeat.
Treatment for hyperthyroidism is important at the beginning of the disease. However, it will not be helpful once your condition progresses into the second phase. During the later stages of the disease, you’ll develop hypothyroidism. You’ll probably need to take hormones such as levothyroxine to replace the ones that your body isn’t producing.
Treatment for subacute thyroiditis is usually temporary. Your doctor will eventually wean you off any medications that have been prescribed to treat the condition.
There are no clear preventive measures for subacute thyroiditis because the precise cause is unknown. Recurrence is not common.
In many cases, subacute thyroiditis resolves on its own without warning. The overall prognosis depends on the extent of damage in the thyroid gland. If a lot of damage is done, you might experience permanent thyroid issues and need ongoing medical attention.
The symptoms of subacute thyroiditis usually go away within 12 to 18 months. In some cases, however, hypothyroidism may end up being permanent. The American Thyroid Association estimates that approximately 5 percent of people with subacute thyroiditis develop permanent hypothyroidism. Permanent health problems are extremely rare.
Call your doctor if you suspect you have subacute thyroiditis. Early diagnosis and treatment can help prevent developing permanent hypothyroidism.