Acute Infectious Thyroiditis: What Patients Need to Know

Woman rubbing sore neck
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The term thyroiditis refers generally to any disorder that involves inflammation of your thyroid gland. Thyroiditis is typically divided into two broad categories—painless and painful—that involve the level of pain they cause to patients.

Among the category of painful types of thyroiditis is a rare form known as acute infectious thyroiditis.

Infectious thyroiditis is classified as suppurative (meaning that it produces pus), nonsuppurative, or septic. It includes all forms of infection, other than viral, and is caused by invasion of the thyroid by bacteria, mycobacteria, fungi, protozoa, or flatworms. 

Infectious thyroiditis is rare, but usually occurs in patients who have a weakened immune system. It is more common in children. About 8 percent of cases are estimated to occur in adults. It is also more common in the fall and winter, especially after infections of the upper respiratory tract.

It's often caused by:

  • a bacterial infection such as streptococcus, staphylococcus, pneumococcus, salmonella, klebsiella, and tuberculosis, among others
  • a fungal infection, including aspergillus, candida albicans and others 

The infection typically leads to an abscess in the thyroid gland.

UpToDate, an electronic reference used by physicians and patients has a useful overview of thyroiditis. According to UptoDate:  

"Acute infectious thyroiditis is characterized by the sudden onset of neck pain and tenderness that is usually unilateral and is accompanied by fever, chills and other symptoms and signs of infection. Most patients have a unilateral neck mass, which may be fluctuant. Acute neck pain and tenderness and a thyroid mass may also be caused by hemorrhage into a thyroid nodule. Thyroid function in patients with acute infectious thyroiditis is usually normal.

A patient who has a painful tender thyroid mass should be evaluated immediately with clinical examination and needle aspiration of the mass, followed by drainage and antibiotic therapy according to the results of studies of the fluid obtained from the neck mass or of blood or other cultures. Ultrasonography or other imaging studies should be performed to confirm the presence of a single abscess. In most instances, rapid diagnosis and treatment is required. Infrequently, surgical drainage or removal is required in patients who do not respond to percutaneous drainage and systemic antibiotic therapy. It is important to differentiate acute infectious thyroiditis from subacute thyroiditis.

Symptoms of Acute Infectious Thyroiditis

If you are experiencing acute infectious thyroiditis, your symptoms may include:

  • Rapid onset of pain and tenderness in one side of your neck
  • Enlarged thyroid gland
  • Fever and chills, a flu-like feeling
  • An enlargement in your neck area, or a movable lump in the neck that you can feel
  • Hot, tender area around the thyroid
  • Painful swallowing
  • Swollen lymph glands

It's not common, but some people with acute infectious thyroiditis will appear with some symptoms of hypothyroid or hyperthyroidism. 

If you have these symptoms, you'll want to see your health care provider as soon as possible for evaluation and treatment.

Diagnosing and Treating Acute Infectious Thyroiditis

If your doctor suspects that you have acute infectious thyroiditis, a number of steps will be taken, including:

  • Ultrasound, MRI, and/or CT scan imaging of your thyroid to determine if you have one or more abscesses that require treatment 
  • Fine needle aspiration (FNA) of the mass in your thyroid. This procedure involves withdrawing some of the fluid or material from your thyroid mass to more fully evaluate it. The sample will be cultured to look for infection. The culture results can help your doctor choose the appropriate antibiotic and/or anti-fungal drug for treatment.
  • In some cases, the biopsy, guided by ultrasound, is used to determine the position and location of an abscess for more accurate drainage.   
  • Out-patient drainage of your thyroid mass or lump
  • Blood tests to evaluate thyroid function, and look for signs of infection in your thyroid gland
  • Prescription of an oral antibiotic medicine that will treat the particular type of infection you have

While most patients respond well to drainage and antibiotic treatment, in rare cases, surgical drainage or surgical removal of the mass be needed. In some cases, removal of half the thyroid gland, known as a lobectomy, may provide more effective treatment.

A Word From Verywell

In some cases, after acute infectious thyroiditis, the thyroid gland may be destroyed to the extent that you end up permanently hypothyroid, and requiring thyroid hormone replacement medication


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Article Sources
  • Burman, Kenneth. Ross, Douglas. Martin, Kathryn. "Overview of thyroiditis." UpToDate. Accessed: August 22, 2008.
  • Shrestha, R. et. al. "Acute and Subacute, and Riedel’s Thyroiditis." Thyroid Manager. December 8, 2015