Inflammation of the thyroid gland, typically associated with neck pain, fever and tenderness of the thyroid gland
Rapid response to glucocorticoid treatment confirms the diagnosis.
Laboratory findings
The ESR is elevated in most patients, as is CRP.
Initially there is often a transient thyrotoxic phase with a slightly decreased TSH concentration and a slightly increased free T4 concentration. This is followed in 20% of cases by transient hypothyroidism 1-2 months after treatment. Permanent hypothyroidism develops in 2-3% of the patients.
Diagnosis: fever, tender thyroid gland, clinical picture of hyperthyroidism, elevated ESR and CRP, rapid response to glucocorticoid therapy. Also TSH and free T4 should be determined at the initial stage; TSH is typically slightly below reference range and free T4 slightly increased.
Thyroid gland scintigraphy is nowadays rarely needed.
Differential diagnosis is sometimes difficult, and then in addition to thyroid gland test results and inflammation parameters, TPO antibodies and TSH-receptor antibodies should be determined, as necessary. Thyroid ultrasound scan combined with fine-needle biopsy may offer additional help.
Course of the disease
Thyroiditis can be managed in primary care.
The disease responds to glucocorticoid treatment within days (the fever comes down, thyroid pain lessens). If there is no response consider alternative diagnoses, such as tonsillitis, and refer the patient to specialized care if necessary.
The symptoms tend to recur if glucocorticoids are discontinued too early or the dose is reduced too quickly.
Serum TSH and free T4 concentrations are monitored if needed according to the patient's clinical condition, if symptoms of hypothyroidism should develop. The initial thyrotoxicosis phase is often followed by a transient hypothyroid phase that does not require treatment. However, if the patient is symptomatic, temporary thyroxine substitution therapy may be commenced. It can usually be discontinued after 6 to 12 months from the symptom onset.
References
Hennessey JV. Subacute Thyroiditis. In: Feingold KR, Anawalt B, et al. (eds.) Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000.2018 Jun 12.[PubMed]