Therapeutic plasma exchange as a bridge to definitive treatment in severe thyrotoxicosis with propylthiouracil-induced neutropenia.

SUMMARY: A 67-year-old Caucasian woman with a history of Graves' disease and atrial fibrillation presented with severe symptoms indicative of an impending thyroid storm, including diarrhea, tremors, palpitations and significant weight loss. Initially treated with methimazole, she was switched to propylthiouracil (PTU) due to an allergic reaction but had to discontinue PTU after developing agranulocytosis. Laboratory tests confirmed suppressed thyroid-stimulating hormone and elevated free thyroxine (FT4) and free triiodothyronine (FT3) levels, alongside neutropenia. The medical team administered high-dose intravenous steroids and granulocyte colony-stimulating factor (G-CSF) in response to her worsening condition and to mitigate infection risk. Despite these measures, her thyroid hormone levels remained high, necessitating therapeutic plasma exchange (TPE). This intervention significantly reduced her thyroid hormone levels and thyrotropin receptor antibodies (TRAb), stabilizing her condition. Post-TPE, she underwent successful radioactive iodine therapy (RAI), which led to a gradual return to euthyroid status and substantial symptomatic relief. Three months post-RAI, she maintained a stable euthyroid state with normalized neutrophil counts, demonstrating the effectiveness of a multidisciplinary approach in managing impending thyroid storm complications. This case highlights the importance of timely and integrated therapeutic interventions in managing life-threatening endocrine emergencies.

LEARNING POINTS: This case highlights the importance of early recognition and management of agranulocytosis induced by antithyroid drugs, particularly in the context of Graves' disease. Therapeutic plasma exchange (TPE) can be an effective bridging therapy for rapid thyroid hormone reduction in thyroid storm, especially when conventional treatments are insufficient or contraindicated. Quick and effective intervention is essential in managing thyroid storm to prevent systemic decompensation, highlighting the importance of a timely and coordinated treatment approach. The role of TPE in managing severe hyperthyroidism underscores the need for flexibility and innovation in critical endocrine emergencies.