Iatrogenic thyrotoxicosis and the role of therapeutic plasma exchange

Thyroid storm or severe thyrotoxicosis results from extreme thyroid hormone elevation. Therapy includes medical management to prevent hormone production, release, recycling, and peripheral conversion while stabilizing adrenergic tone. Thyroid dysfunction is the usual cause but it can be due to excessive thyroid hormone ingestion. Therapeutic plasma exchange (TPE) has been used to rapidly remove protein-bound thyroid hormone. American Society for Apheresis guidelines make a weak recommendation to perform TPE in selected patients in the treatment of thyrotoxicosis based on low quality evidence. We present a case of excessive thyroid replacement hormone ingestion treated by TPE. The patient presented with the clinical picture of thyroid storm, including cardiovascular compromise and massively elevated total and free T3 (525 ng/dL, nl 80-200 ng/dL and 28 pg/mL, nl 2.0-3.5 11 pg/mL), which failed medical therapy. A single, one plasma volume TPE was performed. Both total and free T3 demonstrated substantial declines immediately after TPE with the patient's mental status returning to near-normal. Thyroid hormone extraction efficiency and collection efficacy were calculated as 37.1% and 40.8%, respectively. Prior to discharge on day 6, the patient's compounding pharmacy indicated that a "bad batch" of bovine thyroid gland derived replacement hormone had been produced. TPE appears to be effective in removing protein bound thyroid hormone in extreme iatrogenic thyrotoxicosis.