Easier for the next 'Gen': Early success of one dose rTSH injection prior to I-131 radioligand therapy in children and teens

Introduction: Thyroid stimulating hormone (TSH), TSH-stimulated total body iodine scanning and stimulated thyroglobulin measurement play an important role in management of patients with differentiated thyroid carcinoma.

For many years, patients had to endure withdrawal of levothyroxine therapy and low iodine diet for various lengths of time to obtain TSH-stimulated measurements and whole body iodine scan prior to potential I-131 radioligand therapy. This length of withdrawal is a stress for patients and their families, making them overtly hypothyroid for weeks and potentially exposing them to a period of time when the thyroid cancer is encouraged to grow, with possible delays of treatment and extra blood draws while waiting. Recombinant thyroid stimulating hormone (rTSH) has been used in adults in this capacity for many years with few prior studies in the pediatric population.

Methods: This is a retrospective review of 14 children with diagnosis of differentiated thyroid cancer who received rTSH injections for TSH stimulation. 13/14 patients received two doses of rTSH per usual protocol with a TSH blood draw 24 hours after the first dose of rTSH and just prior to the second administered dose of rTSH. TSH results after one rTSH injection were reviewed. One patient received a single dose rTSH due to side effect of nausea after the first dose.

Results: All 14 patients had TSH levels greater than 30 mIU/L, with the first administered dose of rTSH. Measurement range of 60-215 mIU/L was well above the minimal needed level for TSH-stimulated measurements and I-131 radioligand therapy. 13/14 patients received two doses rTSH per usual protocol. Apart from the one patient who experienced nausea, no other adverse effects were noted in the remaining 13 patients.

Conclusions: Small scale patient review demonstrates that one dose of rTSH is effective in elevating the TSH to an appropriate level for I-131 radioligand therapy and TSH-stimulated measurements. This would obviate the need for levothyroxine withdrawal prior to therapy as well as decreasing the number of blood draws for the patient. Additionally, there is decreased stress on the patient and their family as they navigate a cancer diagnosis and treatment. Larger scale study would be needed to validate.