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Thyroid

(22.05) Severe Acute Radiation Thyroiditis: A Rare Complication of Radioactive Iodine Ablation Therapy

Saturday, May 11, 2024
12:50 PM – 1:05 PM CDT
Location: ePoster Showcase, Empire Ballroom Foyer, Level 2
Introduction : Radiation thyroiditis is a form of painful, acute thyroiditis resulting from radioactive 131I (RAI) treatment for hyperthyroidism or from radiation to treat head and neck cancers. It affects 1-5% of those who received 131I therapy for Graves’ disease, typically presenting 5-10 days after the procedure and is asymptomatic in most patients. Risk factors include high TRAb at diagnosis, high dose of RAI and high fT4. We herein report a patient with severe radiation thyroiditis requiring hospitalization. 

Case(s) Description : 54-year-old woman with Graves' disease diagnosed 2 years ago TSI 3.06 IU/L (< 0.1), status post 28.0 mCi of 131I treatment 2 weeks prior to admission, presented with anterior neck pain, palpitations, tremors, heat intolerance, excessive sweating, dysphagia, dyspnea on exertion, and was found to have A fib/RVR. The patient was afebrile, HR 120-140 bpm, BP 180/80 mm Hg. Physical examination showed enlarged indurated and tender thyroid gland on palpation, visible tremors, and hyperreflexia. Burch Warsofsky point scale score was 65. TSH was < 0.008 uIU/ml (reference range 0.4-4.0) with free T4 >5 ng/dl (0.71-1.51) and total T3 of 567 ng/dl (80-200). Records showed TSH of 2.56 uIU/ml with free T4 of 0.77 ng/dl while on methimazole 15 mg daily, but p</span>atient stopped taking it 8 months ago due to joint pains. She opted for RAI ablation when follow up labs showed TSH < 0.008 uIU/ml and free t4 of 1.85 ng/dl 4 months ago. The patient was started on hydrocortisone 50 mg q8h, propranolol 80 mg q6 hrs and propylthiouracil 200 mg q6h, cholestyramine and SSKI were added later. Free T4 remained >5 for the next 10 days with difficult to control resting tachycardia. Therapy was slowly deescalated as she improved clinically and biochemically (free T4 of 4.39 ng/dl at discharge). She was discharged on methimazole 20 mg daily with continued improvement with free T4 of 3.15 ng/dl 3 days later.

Discussion : 131I therapy is believed to cause release of the stored thyroid hormones causing thyrotoxicosis. A high index of suspicion is necessary to ensure prompt initiation of anti-inflammatory treatment to prevent cardiac complications. Withdrawing thionamides 4-7 days before 131I treatment and resuming them three days after the treatment may help to prevent severe cases. In conclusion, radiation thyroiditis is a rare complication that should be considered in patients with Graves after 131I therapy.