ODP515 Severe thyrotoxicosis caused by subacute thyroiditis

BACKGROUND: Subacute thyroiditis, also named giant cell thyroiditis, painful thyroiditis, and de Quervain's thyroiditis, usually presents with neck pain or discomfort, a tender diffuse goiter and mild or moderate elevation of serum free T4 and T3 levels. Here we report a case of subacute thyroiditis patient presenting with severe thyrotoxicosis. Clinical case: A 27-year-old woman with no significant past medical history presents to the emergency room with palpitations and abnormal EKG with heart rate at 160 beats per minute. She developed a sore throat 3 days prior to the presentation, but she did not have neck pain or fever. She reports a 3-month history of hair loss, headaches and weight gain. Labs showed significantly elevated free T4 greater than 7.7 ng/dl (0.8-1.7) and free T3 level at 20.7 pg/ml (2. 0-4.8), and suppressed TSH less than 0. 01 uIU/ml (0.45-4.5) and normal ESR at 15 mm/hour. Her TPO antibody was greater than 1300 u/ml. Thyroid stimulating immunoglobulin (TSI) and TSH receptor antibody (TRab) were obtained but results were pending when she was discharged from the hospital. She has no typical clinical features of subacute thyroiditis with normal ESR and her free T3 and free T4 levels were significantly elevated. She was discharged on Methimazole and Propranolol and to do neck ultrasound as outpatient and follow-up TSI and TRab results and repeat free T4 and T3 in 1 week. Her neck ultrasound revealed mild hypervascularity but no Graves’ features. Her TSI and TRab were negative and free T4 level had no improvement even on significant dose of Methimazole. All the findings argue against Graves’ disease, but support subacute thyroiditis. Then Methimazole was discontinued and Prednisone was started at 20 mg daily and quickly taper to 5 mg daily in 2 weeks then stopped. After on Prednisone for 3 weeks, her free T4 was close to normal at 2. 0 ng/dl, T3 normal at 120 ng/dl, although TSH is suppressed. After stopped Prednisone for 2 weeks, her free T4, T3 and TSH were all back to normal. She is currently euthyroid without any medication at 5 months after her initial presentation. CONCLUSION: Treatment of patients with subacute thyroiditis is pain relief with NSAID or Prednisone when NSAID is not effective. Anti-thyroid medications are rarely effective even in subacute thyroiditis patient with thyroid storm. Our case illustrated the role of corticosteroids in the treatment of subacute thyroiditis patient with severe thyrotoxicosis. Neck ultrasound and thyroid antibodies including TSI and TRab are critical to make a correct diagnosis in subacute thyroiditis patient with severe thyrotoxicosis. Presentation: No date and time listed