From the Guidelines
Post viral thyroiditis is typically managed with supportive care, and treatment with beta-blockers or levothyroxine replacement may be necessary depending on the phase and symptom severity. The condition typically progresses through three phases: an initial hyperthyroid phase lasting 2-4 weeks, followed by a hypothyroid phase lasting 2-8 weeks, and finally a return to normal thyroid function. During the hyperthyroid phase, beta-blockers like propranolol (10-40 mg three to four times daily) can help control symptoms such as palpitations and tremors, as recommended by the Society for Immunotherapy of Cancer (SITC) toxicity management working group 1. Antithyroid medications are not recommended as the hyperthyroidism is due to release of preformed thyroid hormone rather than increased production. In the hypothyroid phase, levothyroxine replacement (typically starting at 50-100 mcg daily) may be necessary if symptoms are significant, though many patients can be monitored without treatment as this phase is usually temporary, as suggested by the American Society of Clinical Oncology (ASCO) guideline update 1. Regular thyroid function testing every 2-4 weeks is important to track progression through phases. Most patients (80-95%) recover completely within 12-18 months, but approximately 5-20% develop permanent hypothyroidism requiring lifelong thyroid hormone replacement. The condition occurs when viral infections trigger an autoimmune response against thyroid tissue, causing inflammation and disruption of normal thyroid function, with common viral triggers including mumps, coxsackievirus, adenovirus, and influenza. Some key considerations in management include:
- Monitoring thyroid function regularly to track progression through phases
- Using beta-blockers for symptomatic hyperthyroidism
- Considering levothyroxine replacement for symptomatic hypothyroidism
- Being aware of the potential for permanent hypothyroidism and the need for lifelong thyroid hormone replacement in some cases, as noted in the Journal for ImmunoTherapy of Cancer 1 and the Journal of Clinical Oncology 1. It's also important to note that subclinical hyperthyroidism due to destructive thyroiditis, such as postviral subacute thyroiditis, resolves spontaneously and usually does not require treatment apart from symptomatic therapy, as stated in the JAMA study 1.
From the Research
Post Viral Thyroiditis
- Post viral thyroiditis, also known as subacute thyroiditis, is a self-limited inflammatory disease characterized by anterior neck pain 2.
- The condition can be triggered by viral infections, including COVID-19, which can cause inflammation and transient or sustained thyroid dysfunction 3, 4.
- The mechanisms through which SARS-CoV-2 affects the thyroid include direct viral infection of thyroid cells, leading to viral thyroiditis, and an excessive systemic immune response (cytokine storm) 3.
- Post viral thyroiditis can present with hyperthyroidism, followed by hypothyroidism, and eventually restoration of normal thyroid function, although some patients may develop permanent hypothyroidism 2.
Clinical Presentation and Diagnosis
- Patients with post viral thyroiditis may present with symptoms such as anxiety, insomnia, palpitations, unintentional weight loss, diarrhea, and heat intolerance 5.
- The diagnosis of post viral thyroiditis can be established based on clinical presentation, thyroid function tests, and thyrotropin-receptor antibody status 5.
- Thyroid scintigraphy is recommended if thyroid nodules are present or the etiology is unclear 5.
Treatment and Management
- Treatment of post viral thyroiditis should focus on symptoms, with beta blockers used to treat adrenergic symptoms in the hyperthyroid phase, and nonsteroidal anti-inflammatory drugs and corticosteroids used to treat thyroid pain 2.
- In some cases, treatment with antithyroid drugs, radioactive iodine ablation, or surgery may be necessary 5.
- Surveillance and clinical follow-up are recommended to monitor for changes in thyroid function and to manage any potential long-term complications 2, 3.