Efficacy of a single fixed 131I dose of radioactive iodine for the treatment of hyperthyroidism

Abstract

A total of 135 patients were treated for hyperthyroidism with 131I 15 mCi radioiodine ablation. The therapeutic target was achieving hypothyroidism. Between January 2014 and December 2018, clinical records were reviewed and date was collected and reviewed for 135 patients with hyperthyroidism that were referred to the Nuclear Medicine Department at Salmaniya Medical Center, for radioactive iodine (RAI) thyroid gland ablation procedure for definitive treatment of hyperthyroidism. About 39.7% of our patients achieved response between 4-6 months out of which 35.7% of the patients showed response in the first 3 months. 21.4% of the patients took between 7-12 months to show response and only 3.2% responded after 12 months. The most significant response was hypothyroidism comprising of 94.4%. It is also worth mentioning that 4.0% of patients achieved euthyroidism and did not require any follow-up medication. Using fixed dose of RAI of 15mCi for treating various type of Hyperthyroidism, successful treatment with a single dose of RAI can be achieved in 92.7% of the patients, with first therapy failure rate in 7.3%, with few patients requiring additional doses of RAI.

Radiobiology of Combining Radiotherapy with Other Cancer Treatment Modalities

“…The occurrence of hypothyroidism depends on the type of indication, with a low fraction seen in autonomic disease but with a 100% occurrence in patients treated for thyroid cancer (with treatment occurring postthyroidectomy to ablate the so-called remnant). Of note, these pills are generally inexpensive and are taken per os once daily [141].…”

Radioiodine for Graves’ Disease Therapy

“…In calculation approaches, the thyroid volume, RAI uptake, and effective halflife are factors determine the activity dose. It is recommended a delivered activity of RAI about 3-8 MBq (80-220 μCi) per gram of thyroid mass, with absorbed radiation dose 100-150 Gy to restore a euthyroid status, whereas the total ablation dose is in the range 200-300 Gy [12,14,23]. Naturally, the normal thyroid mass is about 20 grams.…”

“…Many physicians prefer a single high RAI dose, which leads to hypothyroidism. Cure rate high dose reach 85% -94.4%, and 66-74% for low dose [4,11,14]. A single high dose or ablative dose concept is preferred by a physician today.…”

“…Radioactive iodine is safe as definitive therapy, cure rates ~80-90%, and cost-effective, rarely or minor side-effects. [4,6,7,[11][12][13][14]. The choice of therapy depends on the patient's preference.…”