Recombinant Human Thyrotropin for Management of Metastatic Differentiated Thyroid Carcinoma in Patients With Deficient Reserve of Endogenous Thyrotropin

adioiodine (RAI) therapy for metastatic follicular cell–derived thyroid cancer (FCDC) requires elevated levels of serum TSH, usually achieved by withdrawal of thyroxine therapy. This is not possible in FCDC associated with hypopituitarism, because of the absence of endogenous TSH. However, the advent of recombinant human TSH (rhTSH) has made diagnostic 131I whole body scans and subsequent RAI therapy possible for patients with FCDC who have deficiency of endogenous TSH. Recently, several reports have been published of patients with metastatic FCDC and pituitary tumor treated after rhTSH administration. We describe 2 cases of FCDC with hypopituitarism, in which therapeutic RAI intervention was possible only with rhTSH administration. Materials and Methods: We searched our medical records from 1950 through 1999 to determine the prevalence of FCDC metastases to the pituitary. Results: We identified 19 cases of FCDC with concomitant hypopituitarism but only 1 with metastasis of FCDC to the sellar region. Of the 19 patients, 2 were treated with rhTSH before RAI therapy. Conclusions: Although metastasis of FCDC to the pituitary is rare as shown by our study, association of pituitary insufficiency with FCDC is more common. The availability of rhTSH has improved therapy for these patients.