To Investigate The Relationship Between Serum TSH Cut-off Value And Early Relapse When Discontinuation Of Antithyroid Drug Treatment Of Graves' Disease

Objective:To analyze the relationship between serum thyroid stimulating hormone(TSH)? thyrotropin receptor antibody(TRAb)and early relapse of Graves' disease(GD)after discontinuation of antithyroid drug(ATD)treatment,thus to find the appropriate time of ATD withdrawal which could reduce early relapse,and the correlation between serum TSH and TRAb level of GD patients after discontinuation of ATD treatment was analyzed at the same time.Methods: GD patients,who were newly diagnosed in the affiliated hospital of Qi-ngdao university(west coach branch)from January 2013 to December 2016,were enrolled in this study.Basic personal information and laboratory test result was c-ollected through outpatient HIS system.Medical history and treatment was asked by telephone.All the patients were in accordance with the diagnostic criteria of Graves disease in China in 2007.All patients' gender,age,relapse time and the re-levant indicators(including TSH,FT3,FT4,TRAb)within 1 year after ATD withdrawal was analyzed.According to the normal reference range of TSH(0.55-4.78mIU/L),all the patients were divided into six groups based on serum TSH level at the time of ATD withdrawal:Group A:0.55?TSH<1.255mIU/L,44 cases;GroupB:1.255?TSH<1.96mIU/L,44cases;Group C:1.96?TSH<2.665mIU/L,39cases;GroupD:2.665?TSH<3.37mIU/L,30cases;GroupE:3.37?TSH<4.075 m IU/L,11cases;Group F:4.075?TSH?4.78mIU/L,9cases.The rate of early relapse(within one year after ATD wit-hdrawal)was analyzed.The relationship between serum TSH level and early relapse and correlation with serum TRAb level was investigated.Result:The recurrence rate was 36.4%?34.1%?10.3%?13.3%?9.1% and 11.1%,respectively.In comparison,the recurrence rate between Group A and Group C?D was significantly different(P<0.05);The recurrence rate between Group B and Group C?D was significantly different(P<0.05);The recurrence rate between Group A and Group B was no significantly different(P>0.05);The recurrence rate between Group C and Group D was no significantly different(P>0.05);Due to the small sample size of group E and F,the results were not comparable.In this study,the rate of early relapse was lowest whenserum TSH level of GD patients after ATD withdrawal between 1.96-3.37mIU/L.The correlation between the serum TSH level and the level of TRAb was-0.036 when GD patients after discontinuation of ATD treatment,there was no statistically significant difference(P>0.05).As FT3,FT4 being control variable,partial correlation between TSH and TRAb was-0.016,there was no statistically significant difference(P>0.05).Thus,there was no correlation between serum level of TSH and TRAb when discontinuation of antithyroid drug treatment under the condition of eliminating FT4,FT3 variables influence.Conclusion: The serum TSH level is one sensitive parameter of the hypothalamuspituitary-thyroid axis function.Being an indicator to evaluate the prognosis of GD patients after ATD treatment,it is clinically important to judge the progress of Graves disease,adjust ATD dosage,select withdrawal time and predict recurrence.GD patients during ATD treatment,either the serum TSH level is a little bit lower(among normal range)or the serum TRAb activity is higher,the treatment time should be appropriately prolonged.The ATD withdrawal should be considerd when serum TSH level is a little bit higher among normal range(>1.96 mIU/L)as well as the serum TRAb activity is negtive.Thus it coule be ruduce relapse and improve remission rate.In this study,the serum TRAb activity was within normal range at the time of ATD withdrawal.There was no statistical correlation between serum level of TSH and TRAb.It was shown that serum TSH level of GD patients after discontinuation of ATD treatment is much more important to influence early relapse.