Conditions: Acute Thyroiditis

What is acute thyroiditis?

Acute thyroiditis is a condition characterized by the sudden development of inflammation and pain of the thyroid gland, usually in one subsite of the thyroid gland rather than the entire gland. Bacterial infections are the usual cause of acute thyroiditis. In addition to pain, patients may also experience fever and a general feeling of being unwell. In some cases, acute thyroiditis can lead to the release of excessive thyroid hormones, resulting in temporary hyperthyroidism. Differentiating acute thyroiditis from a slower-onset subacute thyroiditis is important because acute thyroiditis is more likely to be bacterial and a subacute thyroiditis is more commonly viral. Treatment for bacterial acute thyroiditis usually involves antibiotics to address the underlying bacterial infection, along with pain relievers and anti-inflammatory medications to alleviate symptoms. Once the infection has resolved, individuals typically recover fully and regain normal thyroid function.

What causes acute bacterial thyroiditis?

Common bacteria that can lead to acute bacterial thyroiditis include Staphylococcus aureus and Streptococcus species of bacteria. Infections can occur due to the spread of bacteria from nearby structures, such as the skin or throat, or through the bloodstream from distant sites. Other risk factors for acute bacterial thyroiditis include a compromised immune system, previous thyroid surgery or injury, and certain medical procedures or interventions that disrupt the normal defenses of the thyroid gland.

diagnosis

Diagnosis of acute bacterial thyroiditis begins with a history and physical exam, including identifying any recent infections or procedures in the neck area. Physical examination involving palpation of the thyroid gland may reveal signs of redness, warmth, tenderness and swelling. A laboratory tests such as acomplete blood count (CBC) may be performed to assess for an elevated white blood count, specifically with elevated neutrophils, which would be supportive of a bacterial infection being present in the body. A radioiodine uptake scan may be helpful. Occasionally, a fine-needle aspiration biopsy (FNAB) is conducted to collect a sample of thyroid tissue for analysis, which may confirm the presence of bacterial infection. Imaging studies like ultrasound or CT scans may also be utilized to visualize the thyroid gland and evaluate its size and structure.

It is important for a physician to differentiate the acute bacterial infection of acute bacterial thyroiditis from subacute granulomatous thyroiditis which is far more common. Subacute granulomatous thyroiditis is also painful, as is acute bacterial thyroiditis, but is characterized by a slower onset and protracted resolution than acute bacterial thyroiditis. In subacute granulomatous thyroiditis, a CBC would likely demonstrate more elevation of lymphocytes than neutrophils.

Treatment

The treatment approach for acute thyroiditis aims to resolve the infection and lessen pain. Typically, individuals are prescribed oral antibiotics, chosen according to the suspected or known type of bacteria present, to eliminate the causal bacteria. Nonsteroidal anti-inflammatory drugs (NSAIDs) may also be recommended to reduce pain and inflammation. Surgical drainage may be necessary and accompanied by a search for a pyriform sinus fistula (part of a branchial cleft abnormality), particularly in children with thyroiditis involving the left lobe.