Recombinant Human TSH Increases Uptake and Effective Half-life of Radioiodine in Thyroid Hormone Secreting Metastases of Follicular Thyroid Cancer

Follicular thyroid cancer with thyroid hormone secreting metastases is an extremely rare condition, with only a few cases reported world-wide. We here present the case of a 64-year-old female patient affected by follicular thyroid cancer with extensive thyroid hormone secreting metastases leading to TSH-suppression. We have also summarized the relevant diagnostic and therapeutic approaches and describe, for the first time, the effects of rhTSH-application in this rare tumor entity. In this patient, we found that rhTSH increased I-131-uptake into the thyroid hormone secreting metastases and prolonged the effective half-life of I-131. These effects of rhTSH should be considered when fixed activities of I-131 are prescribed.