Recombinant Human Thyrotropin-Assisted Radioiodine Therapy for Patients with Metastatic Thyroid Cancer Who Could Not Elevate Endogenous Thyrotropin or Be Withdrawn from Thyroxine

The value of recombinant human thyrotropin (rhTSH) as preparation for radioiodine therapy was assessed in 115 patients with metastatic thyroid cancer. Patients who were either unable to elevate endogenous TSH during thyroxine withdrawal, or in whom thyroxine withdrawal was contraindicated for medical reasons were eligible. Their physicians requested rhTSH as part of the Thyrogen Compassionate Use Program. This is a retrospective summary of the nonrandomized uncontrolled experience. We assessed the ability of rhTSH to elevate the serum TSH; to avoid the complications of hypothyroidism; to stimulate radioiodine uptake; and to stimulate the serum thyroglobulin. Disease response and adverse events were also assessed. After rhTSH, the serum TSH levels rose to >or=25mU/L in every patient in whom levels were measured (n = 112). Hypothyroid complications were avoided in 22 of 25 patients who had experienced them in the past, and in 47 of 51 patients who were at high risk for hypothyroid complications. Radioiodine uptake was present on whole-body scans (WBS) in 105 of the 115 patients. Serum thyroglobulin levels were lower than baseline in 73% of patients assessed at 12 months. Cancer-related symptoms were improved in approximately 25%. Two patients had serious adverse events that were thought to be related to rhTSH. rhTSH elevates serum TSH and facilitates radioiodine uptake in patients who cannot produce endogenous TSH or who cannot tolerate hypothyroidism.