SAT-372 Therapeutic Plasma Exchange as Bridging Modality in Thyroid Storm With Contraindications to Anti-thyroid Medications: A Case Report

Abstract Disclosure: M.V. Bondoc: None. C.C. Chua: None. Introduction: Thyroid storm is a life-threatening complication of thyrotoxicosis, characterized by acute, severe manifestations and a high mortality rate of 20-30%. Prompt intervention is essential, with treatment strategies focused on reducing thyroid hormone production, inhibiting the conversion of T4 to T3, and managing the symptoms with anti-thyroid medications. In cases where these medications are contraindicated, therapeutic plasma exchange (TPE) can be used as a bridging modality to definitive intervention. Presentation of the Case This case report describes a 33-year-old female with Graves' disease who initially presented with symptoms of hyperthyroidism, including easy fatigability, exophthalmos, heat intolerance, and palpitations that was treated with methimazole. She developed agranulocytosis leading to the discontinuation of methimazole. Symptoms improved on discontinuation of methimazole and was discharged. However, she was re-admitted and work-up were consistent with sepsis from pneumonia and thyrotoxic heart disease. IV meropenem, sacubitril+valsartan 50 mg/tab twice daily, and carvedilol 6.25 mg/tab ½ tab twice daily were started. Since methimazole was contraindicated, lithium 450mg 1 tab twice daily was started. Symptoms improved and was discharged.She was again re-admitted due to recurrence of symptoms of severe hyperthyroidism and treated as a case of thyroid storm and lithium toxicity with TSH 0.01 uIu/mL, FT4 25.14 pmol/L, creatinine 388 mg/dL, lithium elevated at 1.59 mmol/L, that required to hold lithium. She underwent hemodialysis and repeat lithium level dropped to 0.3 mmol/L however repeat FT4 increased to 41.22 pmol/L. Due to contraindication to methimazole and lithium, therapeutic plasma exchange (TPE) was done. After the first session of TPE, FT4 decreased from 41.22 pmol/L to 25.02 pmol/L. Patient then underwent radioactive iodine therapy at 14 MCI. Post RAI, repeat FT4 was 21.11 pmol/L. Patient was then started on prednisone 60 mg per day and underwent another cycle of TPE. Repeat 2D echo was done which showed improvement of ejection fraction to 65% with resolution of global hypokinesia and diastolic dysfunction. Thyroid function test showed further decrease in FT4 level to 16.95 pmol/L. The symptoms resolved and was discharged stable.Continued follow-ups showed that patient was maintained on levothyroxine 100mcg once daily. Her latest TSH is 9 uIu/mL and her levothyroxine is being adjusted accordingly. Conclusion: Thyroid storm remains a medical emergency requiring rapid and comprehensive management. TPE offers a viable bridging modality to definitive intervention when anti-thyroid medications are contraindicated. Presentation: Saturday, July 12, 2025