Iodine Biokinetics and Radioiodine Exposure after Recombinant Human Thyrotropin-Assisted Remnant Ablation in Comparison with Thyroid Hormone Withdrawal

• Published in: The journal of clinical endocrinology and metabolism 2010-07, Vol.95 (7), p.3283-3290
• Main Authors: Taïeb, D., Sebag, F., Farman-Ara, B., Portal, T., Baumstarck-Barrau, K., Fortanier, C., Bourrelly, M., Mancini, J., De Micco, C., Auquier, P., Conte-Devolx, B., Henry, J. F., Mundler, O.
• Format: Article
• Language: English
• Subjects: Ablation Techniques - methods; Adenocarcinoma, Follicular - radiotherapy; Adenocarcinoma, Follicular - surgery; Biological and medical sciences; Carcinoma, Papillary - radiotherapy; Carcinoma, Papillary - surgery; Combined Modality Therapy; Endocrinopathies; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Half-Life; Humans; Iodine - metabolism; Iodine Radioisotopes - therapeutic use; Medical sciences; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Prospective Studies; Radiometry; Recombinant Proteins - therapeutic use; Thyroid Gland - radiation effects; Thyroid Neoplasms - radiotherapy; Thyroid Neoplasms - surgery; Thyroid. Thyroid axis (diseases); Thyrotropin - therapeutic use; Thyroxine - therapeutic use; Treatment Outcome; Triiodothyronine - therapeutic use; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2009-2528

Context: A few prospective studies have evaluated the use of recombinant human TSH (rhTSH) for radioiodine remnant ablation. Objective: Our objective was to compare the effects of the both TSH regimens on iodine biokinetics in the thyroid remnant, dosimetry, and radiation protection. Design: We conducted a prospective randomized study. Materials and Methods: Eighty-eight patients were enrolled for radioiodine ablation to either the hypothyroid or rhTSH arms. A whole-body scan was performed at 48 and 144 h after therapy. Dose rates were assessed at 24, 48, and 144 h. Urinary samples were obtained during the first 48 h. Thyroglobulin was assessed before and after therapy. Iodine biokinetics in the remnants were calculated from γ-count rates. Radiation-absorbed dose was calculated using OLINDA software. Exposure estimation was based on a validated model. Results: The effective half-life in the remnant thyroid tissue was significantly longer after rhTSH than during hypothyroidism (P = 0.01), whereas 48-h 131I uptakes and residence times were similar. After therapy, thyroglobulin release (a marker of cell damage) was lower in the rhTSH arm. The mean total-body effective half-life and residence time were shorter in patients treated after rhTSH. Residence time was also lower for the colon and stomach. Absorbed dose estimates were lower in the rhTSH arm for the lower large intestine, breasts, ovaries, and the bone marrow. Dose rates at the time of discharge were lower in the rhTSH group with a reduction in cumulative radiation exposure to contact persons. Conclusions: In comparison with thyroid hormone withdrawal, rhTSH is associated with longer remnant half-life of radioactive iodine while also reducing radiation exposure to the rest of the body and also to the general public who come in contact with such patients. The use of recombinant TSH for thyroid remnant ablation is associated with favorable iodine biokinetics, dosimetry, and radiation protection issues in comparison to thyroid hormone withdrawal.