Influence of compound iodine solution on 131I uptake and curative effect of 131I therapy in patients with Graves disease

Objective To investigate the influence of different time discontinuation of compound iodine solution on 131I uptake and curative effect of 131I therapy in patients with Graves disease (GD). Methods A total of 1 585 patients (415 males, 1 170 females; age range: 17-62 years) treated with 131I therapy for the first time between January 2012 and November 2016 were enrolled in this retrospective study. All patients were divided into preliminary treatment group (n=85) and control group (no iodine solution taking, n=1 500). Preliminary treatment group including 4-7 d discontinuation subgroup (group A, n=35), 8-14 d discontinuation subgroup (group B, n=28) and 15-30 d discontinuation subgroup (group C, n=22). The highest radioactive iodine uptake (RAIU), effective half-life, free triiodothyronine (FT3) and free thyroxine (FT4) levels before 131I therapy were compared, and curative effects were evaluated. One-way analysis of variance, Ridit analysis and χ2 test were used to analyze the data. Results The highest RAIU in group A, group B, group C and control group was (64.86±13.20)%, (67.40±9.10)%, (73.46±4.65)% and (74.14±9.87)%, respectively (F=1.658, P>0.05). No significant difference was found in the effective half-life among 4 groups (F=0.651, P>0.05). FT3 level in group A and group B ((11.90±4.85) and (15.51±2.95) pmol/L) was significantly lower than that in control group ((23.98±4.98) pmol/L) and group C ((22.08±2.31) pmol/L; F=13.972, t values: 6.57-12.08, all P 0.05), and no significant difference was found in the complete remission rates among 4 groups (χ2=1.169, P>0.05). Conclusions If pretreatment with compound iodine solution is used before 131I therapy in GD, it is feasible to carry out 131I therapy within 2 weeks after withdrawal. In order to avoid the possibility of severe hyperthyroidism after 131I therapy, it is recommended that radioiodine treatment should be carried out after discontinuation for 4-7 d. Key words: Graves disease; Radiotherapy; Iodine radioisotopes; Iodides; Treatment outcome