Effect of 1110 MBq Radioiodine in Reducing Thyroid Volume in Multinodular Goiter: A New Protocol

Abstract

BackgroundThere is no consensus on the optimal treatment of multinodular goiter (MNG), but in the past few years, the use of radioiodine has increased. This study’s objective was to evaluate adjuvant methimazole (MMI) therapy to increase and standardize radioiodine uptake (RAIU) with a fixed therapeutic 131I dose of 1110 MBq (30 mCi).MethodsOur study included 5 women with MNG treated with MMI, 10 - 15 mg/day for 2 to 4 months, prior to the administration of 1110 MBq 131I (30 mCi); none of the patients developed hypothyroidism during MMI therapy and had average basal TSH levels of 0.32 ± 0.39 mIU/L that increased to 2.6 ± 0.9 mIU/L (P = 0.07).ResultsRAIU increased from 25.6 ± 8.7% to 49.2 ± 8.3% (P = 0.003). All patients were followed for 12 months: median thyroid volume (TV) decreased from 77.2 mL (32.9 - 124.2) to 48.8 ml (12.4 - 68.9) with an average decrease of 46.4 ± 14.8% (P = 0.01). All patients developed hypothyroidism during the first 6 months after radioiodine therapy.ConclusionsThis new therapeutic protocol using MMI as adjuvant therapy is effective in increasing RAIU as well as the deleterious effects of 131I, without increasing the required dose, but leading to thyroid volume decreases similar to those reported with the use of recombinant human thyrotropin (rhTSH) or higher radioiodine doses.

Enhancing the efficacy of 131I therapy in non-toxic multinodular goitre with appropriate use of methimazole: an analysis of randomized controlled study

“…Two other studies, conducted under the supervision of A. Flores-Rebollar and A. Kyrilli, add, moreover, that the application of MMI prior to a 131 I therapy can be a safe, easy and acceptable method to increase TSH concentrations, representing a valid alternative to the widely used rhTSH. This is because both the methods of stimulating RAIU cause an approximately twofold increase in its value [8,9]. Our research shows that the applied adjuvant therapy with MMI caused an over twofold rise not only in RAIU 24 h but also in RAIU 48 h : 2.24 and 2.11, respectively.…”

Thiamazole Pretreatment Lowers the131I Activity Needed to Cure Hyperthyroidism in Patients With Nodular Goiter

“…In the second study, 10 -15 mg/d of MTZ were administered to increase RAIU above 50%, and a fixed 1110 MBq 131 I activity was administered. The average duration was 3 months, and all five patients developed hypothyroidism (12).…”

“…Two previous nonrandomized studies evaluated MTZ as an adjuvant treatment for 131 I therapy of MNG (11,12). In the first study, the authors treated nine patients with different doses of MTZ to obtain a serum TSH Ͼ 6 mU/L and then administered a fixed activity of 1110 MBq (30 mCi) (11).…”

“…The frequent finding of relatively low radioiodine uptake (RAIU) in MNG can compromise the efficacy of 131 I therapy, and very high activities of 131 I may be required in these circumstances. To address this problem, recombinant human TSH (rhTSH) has been used successfully to increase RAIU in MNG (7)(8)(9)(10)(11)(12). However, the use of rhTSH in this indication is not formally recommended (5).…”

Protocol for Management of Hyperthyroidism by Radioactive Iodine (RAIT)-SNMB Guidelines

“…1 Associate Professor, NINMAS, BAEC, 2 Professor, NINMAS, BAEC, 3 Director, BIHS, 4 Director, INMAS, Mitford, BAEC, 5 Director, NINMAS, BAEC, 6 Former Professor, NINMAS, 7 Head, Dept. of Radiology and Imaging, BIHS, 8 Member, Bangladesh Atomic Energy Regulatory Authority, 9…”