Radioiodine therapy for Graves' disease - retrospective analysis of efficacy factors.
BACKGROUND
Radioiodine ((131)I) isotope therapy is the method of choice in the treatment of Graves' disease relapse. The efficiency of this method is dependent on many factors; therefore, the present paper aims to identify the parameters that have a crucial impact on the efficacy of radioiodine therapy for Graves' disease.


METHODS
The authors performed a retrospective analysis of the medical documentation of 700 Graves' disease sufferers treated with (131)I. The patients were divided into three groups depending on the thyroid-absorbed dose of (131)I: group I - 100 Gy, II - 150 Gy, and III - 200 Gy. The authors assessed the influence of gender, age, presence of orbitopathy, TRab titres, thyroid mass, iodine uptake after 24 and 48 hours, and the absorbed dose on the treatment efficacy at one year post-(131)I administration.


RESULTS
The volume of thyroid gland (P < 0.002) and the thyroid-absorbed dose (P < 0.001) were the only factors that had a significant impact on the outcome of the treatment. The likelihood of hyperthyroidism persisting (odds ratio: 3.71, 95% confidence interval: 2.4-5.87) was greatest in patients from group I. In group II, with thyroid volume amounting both to 25 mL and to 25-50 mL, the percentage of hyperthyroidism was lowest (1 and 0%). However, with thyroid volume > 50 mL, the percentage of hyperthyroidism was lowest in group III (10%).


CONCLUSIONS
The absorbed dose of (131)I and the volume of the thyroid gland are two parameters that have a significant influence on the efficacy of radioiodine therapy for Graves' disease. 150 Gy is the optimal dose for glands < 50 mL. A goitre > 50 mL requires an absorbed dose of 200 Gy in order to minimise the risk of recurrent hyperthyroidism.
Department of Nuclear Medicine Medical University of Bialystok. piotrmjs@wp.pl.
Piotr
P
Szumowski
Saeid
S
Abdelrazek
Agnieszka
A
Kociura Sawicka
Małgorzata
M
Mojsak
Jerzy
J
Kostecki
Monika
M
Sykała
Janusz
J
Myśliwiec
D000328:Adult; D005260:Female; D006111:Graves Disease / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000187:drug effects* / Q000473:pathology; D016896:Treatment Outcome
D007457:Iodine Radioisotopes