Establishment Of Reference Intervals And Analysis Of Influence Factors For Serum Indicators Of Thyroid Function Among Healthy Adults In A Tertiary Hospital Of Guizhou Province

Objective:To establish reference intervals for serum indicators of thyroid function including total triiodothyronine(TT3),total thyroxine(TT4),free triiodothyronine(FT3),free thyroxine(FT4)and thyrotropin(TSH)among healthy adults in Guizhou Provincial People's Hospital and to analyze the influence of gender,age,season and urinary iodine levels on these indicators.Methods:Firstly,the precision,accuracy and linear range of Beckman Coulter Dx I 800 automated chemiluminescence analyzer in detecting TT3?TT4?FT3?FT4?TSH?TPOAb and Tg Ab were evaluated with the reference of Clinical and Laboratory Standards Institute(CLSI)guidelines.Then according to the requirements of the National Academy of Clinical Biochemistry(NACB)laboratory medicine practice guidelines,reference population were screened out to detect the levels of TT3,TT4,FT3,FT4 and TSH.These indicators' reference intervals were established by the requirements of CLSI C28-A3.Inductively coupled plasma mass spectrometry(ICP-MS)was used to detect urinary iodine concentration,and statistical analysis was conducted to explore the influence of gender,age,season,and urinary iodine levels on these five indicators.Results: 1.A total of 339 reference populations with complete data meeting the inclusion criteria were enrolled.Reference population were grouped by gender,age,season,urine iodine levels,including gender groups(200 males and 139 females),age groups(18~29 years old with 79,30~39 years old with 97,40~49 years old with 68,50~59 years old with 55,?60 years old with 40),season groups(winter group with 189,summer group with 150),the level of urinary iodine concentration(UIC) groups:UIC=0~99?g/L group with 50,UIC=100~199?g/L group with 79,UIC=200~299?g/L group with 19,UIC?300?g/L group with 12.2.The precision,accuracy and linear range of TT3,TT4,FT3,FT4,TSH,TPOAb and Tg Ab detected by Beckman DXI800 meeted the performance verification requirements for biochemical projects of China National Accreditation Service for Conformity Assessment(CNAS)CL02 A003:2018 or WS/T 420-2013.3.Reference intervals for the overall reference population established in this study: TT3(1.10~2.21nmol/L),TT4(80.31~151.03nmol/L),FT3(4.2~7.2pmol/L),FT4(8.62~14.41pmol/L)and TSH(0.71~5.90 m IU/L),which passed verification of WS/T402-2012.4.Gender factors:there was no statistical significance in FT4 between different gender groups(P>0.05),but with statistical significance in TT3,TT4,FT3 and TSH(P<0.05);TT4 and TSH were related with gender(P<0.05),TT3,FT3 had significant correlation with gender(P<0.01).Age factors: FT3 in the ?60 years old group was significantly different from the 19~29 years old group,30~39 years old group,and 40~49 years old group(P<0.05).TSH in the ?60 years old group had statistical significance in comparing with 19~29 years old group and 30~39 years old group,respectively(P<0.05).TT3,TT4,and FT4 were not associated with age(P>0.05),FT3 was negatively correlated with age(P<0.01),and TSH was positively correlated with age(P<0.01).Season factors: there were statistical difference in TT3,TT4,FT3,FT4 in summer and winter(P<0.05),while the level of TSH in winter was not significantly different from that in summer(P>0.05);TT3,TT4,FT3 and FT4 had correlation with seasons(P<0.01),but TSH had no correlation with seasons(P>0.05).Urinary iodine factors: there was no statistical significance in TT3,TT4,FT3,FT4 and TSH among different urinary iodine levels(P>0.05),TT3,TT4,FT3,FT4,TSH had no correlation with urinary iodine(P>0.05).Conclusions: 1.The study establish the reference intervals of TT3,TT4,FT3,FT4 and TSH among healthy adults detected by Beckman Dx I 800 automated chemiluminescence analyzer and supporting reagents in Guizhou Provincial People's Hospital:TT3(1.10~2.21nmol/L),TT4(80.31~151.03nmol/L),FT3(4.2~7.2pmol/L),FT4(8.62~14.41pmol/L)and TSH(0.71~5.90 m IU/L),which provide valuable references for the diagnosis of thyroid diseases.2.The study provides some data supports for establishing reference intervals of TT3,TT4,FT3,FT4 and TSH by gender,age and season groups.