L-carnitine treatment in a seriously ill cancer patient with severe hyperthyroidism

Abstract

Objective: To report a case of vaccine-induced Graves' disease successfully managed with L-carnitine and propranolol and without antithyroid drugs (ATDs). ATDs sometimes need to be used at low doses or can be contraindicated/refused. One of the ancillary compounds available is L-carnitine. L-carnitine is a naturally occurring quaternary amine, which acts by impairing thyroid hormone access to the cell nucleus. Report: A 32-year-old Chinese woman with a synovial sarcoma received radiotherapy, chemotherapy and experimental immunotherapy. Two months after the start of immunotherapy, she developed autoimmune hyperthyroidism [thyroid-stimulating immunoglobulins (TSI)=152%, normal values <140]. Left untreated, hyperthyroidism worsened (TSI=248%), so that for 3 months she took L-carnitine (1-4 g/d) and propranolol (20-80 mg/d). Though the hyperthyroidism worsened biochemically (FT4>50 pg/ml, FT3>20 pg/ml, TSI=501%), it was tolerated very well clinically. Fearing a life-threatening thyroid storm, she agreed to have, while still hyperthyroid, total thyroidectomy. The operation was uneventful. Conclusions: This case expands previous observations involving two more patients who survived thyroid storms while being treated with L-carnitine (combined with low doses of ATD). Taking also into account that tissue concentrations of L-carnitine decrease in hyperthyroidism, there is room for wide therapeutic use of L-carnitine in several hyperthyroidism settings.