Correlation between the thyroid autoimmune state after 131I treatment and the early hypothyroidism in patients with Graves disease

Objective To study the changes of the serum levels of thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb) after 131I treatment in patients with Graves disease,and investigate the correlation between the early hypothyroidism and serum levels of TPOAb,TGAb after 131I treatment.Methods The serum levels of TPOAb and TGAb of 167 patients with Graves disease were detected before treatment and 3,6,12,18 months after 131I treatment.According to the levels of TPOAb and TGAb,all patients were divided into positive antibodies group (72 cases) and negative antibodies group(95 cases),and the incidence of the early hypothyroidism was compared between two groups after 131I treatment.According to the incidence of the early hypothyroidism,all patients were divided into early hypothyroidism group(64 cases) and non-early hypothyroidism group(103 cases),and the variations of thyroid function and thyroid autoantibody were detected.Results The incidence of hypothyroidism in 18 months after 131I treatment in positive antibodies group was 19.4％(14/72),while that in negative antibodies group was 7.4％(7/95),and there was significant difference between two groups (P ＜ 0.05).The positive rate of TPOAb and TGAb was highest in 6 months after 131I treatment,but there was no significant difference compared with that before treatment (P ＞ 0.05).The positive rate of TPOAb and TGAb was decreased in 3,12,18 months after 131I treatment.There was significant difference in the positive rate of TPOAb and TGAb between the time before treatment and 18 months after 131I treatment[15.6％(26/167),19.8％(33/167)](P＜ 0.01).The serum level of TPOAb and TGAb in early hypothyroidism group was higher than that in non-early hypothyroidism group [(433.2 ± 98.4) kU/L vs.(211.4 ± 76.5) kU/L; (165.7 ± 41.6) kU/L vs.(89.5 ± 21.1) kU/L,P ＜0.01].Conclusions The levels of TPOAb and TGAb before treatment is related to the probability of the early hypothyroidism,and play a guided role in 131I treatment of Graves disease. Key words: Hyperthyroidism;  Immunoglobulins,thyroid-stimulating;  Iodine isotopes; Hypothyroidism