Effect of radioiodine-131 therapy for Graves disease and its correlation with thyroid weight

Objective To investigate the effects of 131I therapy for Graves disease and how these correlates with thyroid weights.Methods All the 2895 patients with Graves' hyperthyroidism who received 131I therapy between July 2003 and April 2009 were intensively followed up,among which,2045(mean age 41±13 years,including 639 males and 1406 females) were successfully followed up.According to the computed thyroid weights by radionuclide imaging,1850 patients with one-dose 131I treatment were divided into A group(≤40 g,n=477),B group(41～60 g,n=758),C group(61～80 g,n=350) and D group(80 g,n=265).Curative effects of all patients were judged only in a single visit,namely,each patient was evaluated once for therapeutic efficacy.Stepwise logistic regression was used to analyze the influencing factors of efficacy with 131I therapy and the correlation between thyroid weights and curative effects.Results Single dose of 131I therapy,led to euthyroidism in 47.99%(846/1763),early hypothyroidism in 31.0%(92/297) and late hypothyroidism in 42.43%(659/1553) of all patients.Euthyroidism was seen in 86.32%(1597/1850) of the patients,improvement in 11.73%(217/1850),relapse(no change) in 1.94%(36/1850),with the overall rate of response being 98.05%(1814/1850).Of the patients in groups A through D,euthyroidism was seen in 87.2%,86.5%,86.3% and 84.2%,overall response in 97.3%,98.3%,97.4% and 99.6%,early hypothyroidism in 34.2%,24.2%,37.5% and 35.3%,and relapse(no change) in 2.7%,1.7%,2.6% and 0.4%,respectively,of all cases,with no significant difference among the groups(P0.05).However,the incidence of late hypothyroidism was 54.8%,42.2%,33.9% and 32.5% respectively in groups A through D.Thyroid weight seemed to be an important factor for late hypothyroidism(P0.01),with statistical differences found between groups A and B,A and C,A and D,B and C,B and D(P0.01).Conclusion 131I therapy appeared therapeutically effective for Graves disease.Thyroid weight may be close correlated with late hy pothyroidism,with the lower thyroid weight before treatment,the higher incidence of late hypothyroidism.