DIAGNOSTIC-ACCURACY OF I-131 SCANNING WITH RECOMBINANT HUMAN THYROTROPIN VERSUS THYROID-HORMONE WITHDRAWAL IN A PATIENT WITH METASTATIC THYROID-CARCINOMA AND HYPOPITUITARISM

The diagnostic and therapeutic use of radioactive iodine in patients w ith thyroid cancer requires a sufficient serum concentration of thyrot ropin (TSH) for efficient thyroid tissue uptake of radioiodine. Recomb inant human TSH (rhTSH) is a promising new agent, which appears to fac ilitate radioiodine scanning with similar efficacy to thyroid hormone withdrawal without the immunologic side-effects of bovine TSH (bTSH) a dministration. Patients with thyroid cancer and concomitant secondary hypothyroidism are particularly difficult to treat because of their in ability to elevate endogenous TSH and the limitations of bTSH administ ration. We describe a patient with metastatic thyroid carcinoma and se condary hypothyroidism with metastases visible only after administrati on of rhTSH previously unappreciated on thyroid hormone withdrawal sca ns. This patient exemplifies the usefulness of rhTSH administration be fore radioactive iodine for this group of patients.