Radioiodine treatment of thyroid cancer with the aid of recombinant human thyrotropin.

OBJECTIVE To update endocrinologists on the use of recombinant human thyrotropin (thyroid-stimulating hormone or TSH) (rhTSH) in thyroid diseases, with an emphasis on thyroid cancer. METHODS We reviewed the available literature on potential uses of rhTSH, including published studies and case reports. RESULTS Clinical trials have shown that rhTSH injections stimulate radioiodine uptake into normal and malignant thyroid tissue almost as well as that found in the hypothyroid state. The benefit to the athyreotic patient is the avoidance of the disability of hypothyroidism. When rhTSH is used in the doses currently recommended for scanning, few negative side effects occur. The more rapid clearance of iodine in the euthyroid state, however, may necessitate the use of more radioiodine to achieve the same amount of irradiation to metastatic lesions. We have used rhTSH for both dosimetric studies and therapy. This approach is essential in patients who cannot make sufficient endogenous TSH (because of hypothalamic-pituitary disease or medications that suppress TSH). Other patients with widespread metastatic lesions who have serious complications when allowed to become hypothyroid also benefit from rhTSH. Finally, we have found that rhTSH may provide new insights into the biologic features of thyroid cancer when used in combination with positron emission tomographic scanning. Use in the treatment of nonmalignant thyroid conditions such as toxic multinodular goiter is also feasible. CONCLUSION Overall, rhTSH provides a new and clinically important advance for patients with thyroid disease, especially thyroid cancer.