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

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.

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.

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.