A Pragmatic Protocol for I-131 rhTSH-Stimulated Ablation Therapy in Patients With Renal Failure

Abstract

Ablation of thyroid remnants in patients with differentiated thyroid carcinoma and renal failure can be challenging because of the altered and variable clearance rates of iodine from the blood secondary to variations in dialysis protocols, which complicate the selection of the appropriate I-131 dose. The advent of recombinant human TSH allows a simpler approach to dosimetry and ablation without rendering the patient hypothyroid. Avoidance of hypothyroidism may be an important consideration for patients who are experiencing various morbidities from conditions associated with renal failure. Three patients on dialysis, who had undergone total thyroidectomy and were euthyroid on L-thyroxine replacement, were given diagnostic doses of I-131 followed by blood and whole-body retention measurements through serial dialyses to determine individual blood clearance rates. After administration of rhTSH, each patient received an ablative dose of I-131 calculated to keep total body dose below 1 Gy. The treatments were administered without complications, and in follow-up imaging of 2 available patients, the ablations were demonstrated to be complete. Dosimetry performed on euthyroid dialysis patients permits I-131 dose selection and avoids the additional morbidity of hypothyroidism.