Acute infectious thyroiditis is a rare thyroid gland infection. This type of infection is painful, associated with a fever, and progresses rapidly.

Symptoms

Acute infections, by definition, are the type of infections that cause unpleasant symptoms within a short period of time. If you or your child develop acute infectious thyroiditis, you can expect the effects to rapidly worsen. Symptoms may include:

• Rapid onset of pain and tenderness in one side of your neck
• Fever and chills (a flu-like feeling)
• Enlarged thyroid gland or an enlargement in your neck area
• A movable lump in your neck
• A warm, red, or tender area in the neck
• Painful swallowing
• Swollen lymph glands

You can also develop symptoms of hypothyroidism (low thyroid hormone function) or hyperthyroidism (excess thyroid hormone function), although your thyroid function is likely to remain stable during a bout of acute infectious thyroiditis.

Acute infectious thyroiditis can produce a number of complications, the most common of which is an abscess, an encapsulated (closed-off) infection that is difficult to treat with antibiotics.

Systemic infection, which is the spread of the infection to another part of your body, is a rare complication. Bleeding into the thyroid gland can occur, resulting in swelling, possible respiratory symptoms, and damage to the thyroid gland. While it is uncommon, long-term thyroid dysfunction due to damage to the thyroid gland can occur after the infection is completely resolved.

Causes

Infectious thyroiditis is usually caused by a bacterial infection. Most often, the culprit is a Gram-positive bacterium such as S. aureus or Streptococci. Gram-negative organisms involving the oropharynx can also be to blame. Less commonly, acute infectious thyroiditis can be caused by mycobacteria or fungi, almost always in immunocompromised individuals.

Diagnosis

Physical Examination

Gently palpate (feel) your neck and thyroid gland, as well as nearby lymph nodes to check the size and texture of any growth.

Diagnostic Imaging Tests

Diagnostic examinations may include a neck ultrasound, computerized tomography (CT) scan, or magnetic resonance imaging (MRI), as well as a thyroid uptake scan.

Aspiration test can help identify whether thyroiditis is suppurative (contains pus) or non-suppurative.

Blood Tests

You may need blood tests, specifically a complete cell count (CBC), which can show an elevated white blood cell count with an infection, and thyroid function tests, which are usually altered by non-infectious inflammation of the thyroid gland, like non-infectious thyroiditis.

Fine Needle Aspiration

Fine needle aspiration (FNA) is a procedure that involves withdrawing some of the fluid or tissue from your thyroid gland. In some cases, the FNA is guided by ultrasound to determine the position and location of an infection or abscess.

Treatment

Oral antibiotics commonly used for this type of infection include penicillin, clindamycin, or a combination of macrolide and metronidazole.

Percutaneous drainage is a procedure used to remove the infectious fluid with a needle.

Surgical drainage of an infection or an abscess is required if your infection does not improve with percutaneous drainage and antibiotic therapy.

Rarely, surgical removal of part of the thyroid gland may be needed as well. In some cases, removal of half the thyroid gland, known as a hemithyroidectomy, may provide more effective treatment.