Establishment Of Reference Intervals Of Thyroid Function And The Effects Of Iodic Nutriture And Menstrual Cycle In Healthy Reproductive Woman

ObjectiveAccording to the analysis of the effects of different iodic nutriture on thyroid function,to establish the reference intervals of thyroid function for healthy woman of reproductive age with normal phenotype,in Hefei.meanwhile,to investigate the effects of menstrual cycle changes on the determination of thyroid function.MethodsFrom the cross-sectional survey data on thyroid diseases and iodic nutriture of 3000 residents in a community of Hefei from September to December in 2016,According to the inclusion criteria,209 healthy individuals with normal phenotype aged from 18 to 39 were screened out in this study.Divided into 18-29 and 30-39 age groups by age.There were 81 males(18-29 years old 43 cases,30-39 years old 38 cases),of whom 53 cases of iodine adequate,28 cases of iodine excessive;128 females(18-29 years old 62 cases,30-39 years old 66 cases),of whom 92 cases of iodine adequate,36 cases of iodine excessive.Female group,according to the menstrual cycle,in early follicular phase(n=36),in late follicular phase(n=26),in corpus luteum phase(n=33),and in late corpus luteum phase(n=33).All serum samples were tested for total triiodothyronine(TT3),total thyroxine(TT4),free triiodothyronine(FT3),free thyroxine(FT4),thyroid stimulating hormone(TSH),thyroid peroxidase antibodies(TPOAb),and thyroglobulin antibodies(Tg Ab);females' Serum samples were tested for thyroxine-binding globulin(TBG),follicle stimulating hormone,luteinizing hormone,estradiol,progesterone,using electrochemiluminescence immunoassay detection technology.Urinary iodine concentration was determined by the ammonium persulfate method,based on the Sandell-Kolthoff reaction.Results(1)There were no significant differences in levels of serum TT3,TT4,FT3,FT4,TSH between the two age groups of reproductive woman.However,The levels of serum TSH in the 30-39 age group were lower than that in the 18-29 age group,in males(P<0.01).(2)The levels of serum TT3,TT4,FT3,FT4 between the two age groups of reproductive woman were significantly lower than those of men(P<0.01).There was no significant differences in the levels of serum TSH between men and women,in 18-29 age group;but in 30-39 age group,which of women were higher than men(P<0.01).Both two age group,except for serum TSH,the levels of serum TT3,TT4,FT3,FT4 in female group were lower than in female and male overall group(P<0.05).In 18-39 all age group,except for TSH,the levels of serum TT3,TT4,FT3,FT4 in female group were lower than in male group(P<0.01).Compared with the female and male overall group,except for serum TSH,the level of serum TT3,TT4,FT3,FT4 were decreased in female group(P<0.01);while in the male group those were increased(P<0.01).(3)when the iodine was excessive,the levels of serum TT4,FT4,TSH in female group,male group and overall group were lower than the iodine was adequate,only the female group's serum TT4 had a significantly decrease(P<0.05).(4)When the iodine was adequate,the levels of serum TT3,TT4,FT3,FT4 in female group were lower than in male group(P<0.01).Compared with the female and male overall group,the level of serum TT3,TT4,FT3,FT4 were decreased in female group(P<0.01);while in the male group those were increased(P<0.01).(5)The reference intervals of thyroid function,in female group:TT3(1.23~2.26)nmol/L,TT4(65.98~132.47)nmol/L,FT3(3.80~5.68)pmol/L,FT4(11.51~15.87)pmol/L,TSH(0.91~4.11)m IU/L;in male group: TT3(1.60~2.66)nmol/L,TT4(70.54~156.06)nmol/L,FT3(4.36~6.47)pmol/L,FT4(11.59~20.53)pmol/L,TSH(0.93~4.01)m IU/L;in male and female overall group: TT3(1.24~2.57)nmol/L,TT4(66.70~145.08)nmol/L,FT3(3.84~6.31)pmol/L,FT4(11.51~19.57)pmol/L,TSH(0.93~4.07)m IU/L.(6)There were no significant differences in the levels of serum TT3,TT4,FT3,FT4,TSH,TBG among reproductive woman at the different phases of menstrual cycle(P>0.05).However,there was a positive correlation between TBG and TT4,TT3 at each phases of menstrual cycle(P<0.05).Conclusion(1)The reference intervals of thyroid function of reproductive woman is unique,which is not affected by the changes of menstrual cycle,but the effect of iodine nutritional status on synthesis of thyroid hormone.Therefore,it is helpful to guide the scientific intake of iodine-containing foods by focusing on the iodine nutritional status in reproductive woman.(2)According to adequate iodine intake,the reference intervals of thyroid function of local woman of reproductive age are established: TT3(1.23~2.26)nmol/L,TT4(65.98~ 132.47)nmol/L,FT3(3.80~5.68)pmol/L,FT4(11.51~15.87)pmol/L,TSH(0.91~4.11)m IU/L.This can evaluate the pre-pregnancy thyroid function of reproductive woman better,guide pregnancy properly,and achieve the purpose of conceiving healthy fetuses,so as to meet the demands of precise medical plan in china.