From the Guidelines
Subacute thyroiditis is a temporary inflammatory condition of the thyroid gland that typically follows a viral upper respiratory infection, causing pain and tenderness in the thyroid gland, along with symptoms of hyperthyroidism followed by hypothyroidism before eventually returning to normal function.
Definition and Causes
Subacute thyroiditis is characterized by inflammation of the thyroid gland, which can lead to the release of stored thyroid hormones into the bloodstream, resulting in symptoms of hyperthyroidism, such as rapid heartbeat, anxiety, and weight loss. This condition is often preceded by a viral upper respiratory infection, which triggers an immune response that damages thyroid follicles 1.
Symptoms and Phases
The condition progresses through distinct phases, including a hyperthyroid phase, followed by a hypothyroid phase, before eventually returning to normal function. Symptoms can vary depending on the phase, but may include pain and tenderness in the thyroid gland, rapid heartbeat, anxiety, weight loss, and fatigue.
Treatment and Management
Treatment primarily focuses on symptom management, with beta-blockers such as propranolol (10-40mg three times daily) used to control hyperthyroid symptoms, and temporary levothyroxine may be needed during the hypothyroid phase. For mild cases, NSAIDs like ibuprofen (400-600mg every 6-8 hours) may be prescribed, while for more severe pain, prednisone (40mg daily, tapered over 2-4 weeks) may be used 1. It is essential to monitor thyroid function closely, as the condition can progress to hypothyroidism, and treatment should be adjusted accordingly.
Monitoring and Follow-up
Regular monitoring of thyroid function is crucial, with TSH and FT4 levels checked every 4-6 weeks in asymptomatic patients on immune checkpoint inhibitor therapy 1. In symptomatic patients, TSH and FT4 levels should be used for case detection, and T3 levels may be helpful in highly symptomatic patients with minimal FT4 elevations. Endocrine consultation should be considered in cases of persistent thyrotoxicosis or severe symptoms.
From the Research
Definition and Characteristics of Subacute Thyroiditis
- Subacute thyroiditis (SAT) is an inflammatory thyroid disease characterized by anterior neck pain and a triphasic disease pattern of thyroid dysfunction 2, 3.
- The condition typically starts with a phase of hyperthyroidism (thyrotoxicosis) due to the release of preformed thyroid hormone from damaged thyroid cells, followed by hypothyroidism, and eventually restoration of normal thyroid function 2, 3.
- Some patients may develop permanent hypothyroidism, with treatment with only ibuprofen and positive thyroid peroxidase antibody (anti-TPO) being determined as the main risk factors for permanent hypothyroidism 4.
Treatment of Subacute Thyroiditis
- The main purpose of treatment is to relieve pain and control the inflammatory process, with nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids being indicated for the treatment of thyroid pain 4, 2, 3.
- Steroid therapy has been found to be effective for moderate to severe SAT, providing relief from acute symptoms, but not being a risk factor for recurrence 5.
- Low initial doses of steroid (15 mg) are preferred over high initial dosage (30-40 mg), and an extended tapering period may help lower recurrence rates 5.
- Intrathyroidal steroid injections are potentially a better alternative to oral prednisone with regard to safety and speed of action, but further investigation is required 5.
Management and Follow-up
- Treatment of subacute thyroiditis should focus on symptoms, with beta blockers being used to treat adrenergic symptoms in the hyperthyroid phase, and thyroid hormone therapy being used in patients with signs and symptoms of hypothyroidism or permanent hypothyroidism 2, 3.
- Surveillance and clinical follow-up are recommended to monitor for changes in thyroid function, with patients being monitored for recurrence and potential development of permanent hypothyroidism 4, 2, 3.