SAT-393 - Subacute Thyroiditis Requiring Extended Duration of Steroid Therapy

Background:
Subacute thyroiditis (SAT) is a self-limiting inflammatory thyroid disease. Although it usually improves on its own within weeks, it needs treatment when patients have pain, fever and symptoms of thyrotoxicosis (1). The American Thyroid Association guidelines recommend glucocorticoid therapy (prednisone 40 mg daily for 1–2 weeks, then tapered over 2–4 weeks or more per the clinical response) for patients with moderate to severe symptoms (2). Typically, a 2-8 week course of prednisone is required and occasionally the course may be prolonged (3,4).

Case Presentation:
A 40-year-old female presented with a one-month history of throat pain, palpitations and biochemical thyrotoxicosis, including suppressed TSH: 0.01 µIU/mL (0.55–4.78), elevated free T4: 4.4 ng/dL (0.8–1.8), total T3: 386 ng/dL (76–181) and an elevated erythrocyte sedimentation rate: 69 mm/hr (0–20), and markedly reduced 24-hour radioactive iodine uptake of 0.6%, consistent with subacute thyroiditis. Thyroid autoantibodies were negative. Treatment with oral prednisone 40 mg daily led to rapid symptomatic improvement. However, symptoms recurred once the dose tapered down to 20mg/day, requiring escalation to 30 mg/day for an additional four weeks. Follow-up thyroid function tests after one month showed normalization of TSH, free T4, and total T3. After more than two months of prednisone therapy, her symptoms fully resolved and prednisone was successfully tapered and discontinued after a total treatment duration of 10 weeks.

Conclusion:
This case highlights an atypical course of subacute thyroiditis requiring prolonged corticosteroid therapy due to symptom recurrence during dose tapering. Although SAT typically responds rapidly to short-term steroid treatment, relapse may occur and necessitate extended therapy. Close monitoring of clinical symptoms and thyroid function tests is essential to guide gradual tapering and prevent premature discontinuation of corticosteroid therapy.

References:
(1) Yuan A, et al. Comparison of treatment outcome between glucocorticoids and non-steroidal anti-inflammatory drugs in subacute thyroiditis patients-a systematic review and meta-analysis. Front Endocrinol (Lausanne). 2024 Apr 23;15:1384365.
(2) Ross DS, et al. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis. Thyroid. 2016 Oct;26(10):1343-1421
(3) Duan L, et al. Short-Term Versus 6-Week Prednisone In The Treatment Of Subacute Thyroiditis: A Randomized Controlled Trial. Endocr Pract. 2020 Aug;26(8):900-908.
(4)Hepsen S, et al. The Evaluation of Low- and High-Dose Steroid Treatments in Subacute Thyroiditis: A Retrospective Observational Study. Endocr Pract. 2021 Jun;27(6):594-600

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