Hemiplegia after Thyrotropin Alfa in a Hypothyroid Patient with Thyroid Carcinoma Metastatic to the Brain

E FFECTIVE radioiodine treatment of thyroid cancer is dependent on an increase in serum TSH concentration in response to LT4 withdrawal. The major disadvantage to thyroid hormone withdrawal is the development of symptomatic hypothyroidism. More concerning, although not common, is the potential for accelerated tumor growth mediated by TSH (1-8). The use of recombinant human TSH (TSH alfa) without LT4 withdrawal prevents the development of hypothyroidism and has been approved in diagnostic radioiodine scanning (9, 10). It is unknown whether short-term administration of TSH results in growth of thyroid cancer in patients. We report a patient with follicular thyroid cancer metastatic to the skeleton, brain, and clivus. Hypopituitarism resulted from a metastatic clival lesion that involved the pituitary gland. TSH alfa, in a compassionate use protocol, was administered before radioiodine treatment. Forty-eight h after TSH alfa administration, the patient developed hemiplegia.