National Guideline Centre (UK). Thyroid Function Tests: Thyroid Disease: Assessment and Management: Evidence Review C. National Institute for Health and Care Excellence (NICE): London, UK; 2019. Available from: https://www.nice.org.uk/guidance/ng145 [Last accessed: February 24, 2023].
2.
AlexanderEK, PearceEN, BrentGA, et al.Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and the postpartum. Thyroid, 2017; 27(3):315–389; doi: 10.1089/thy.2016.0457
3.
TaylorPN, RazviS, PearceSH, et al.Clinical review: A review of the clinical consequences of variation in thyroid function within the reference range. J Clin Endocrinol Metab, 2013; 98(9):3562–3571; doi: 10.1210/jc.2013-1315
4.
GarberJR, CobinRH, GharibH, et al.American Association of Clinical Endocrinologists and American Thyroid Association Taskforce on Hypothyroidism in Adults. Clinical practice guidelines for hypothyroidism in adults: Cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Thyroid, 2012; 22(12):1200–1235; doi: 10.1089/thy.2012.0205
5.
YamadaS, HoriguchiK, AkuzawaM, et al. The impact of age- and sex-specific reference ranges for serum TSH and FT4 on the diagnosis of subclinical thyroid dysfunction: A multi-center study from Japan. Thyroid, 2023 [Epub ahead of print]; doi: 10.1089/thy.2022.0567
6.
JonesGRD, HaeckelR, LohTP, et al.IFCC Committee on Reference Intervals and Decision Limits. Indirect methods for reference interval determination—Review and recommendations. Clin Chem Lab Med, 2018; 57(1):20–29; doi: 10.1515/cclm-2018-0073
7.
TakedaK, MishibaM, SugiuraH, et al.Evaluated reference intervals for serum free thyroxine and thyrotropin using the conventional outliner rejection test without regard to presence of thyroid antibodies and prevalence of thyroid dysfunction in Japanese subjects. Endocr J, 2009; 56(9):1059–1066; doi: 10.1507/endocrj.k09e-123
8.
SriphrapradangC, PavarangkoonS, JongjaroenprasertW, et al.Reference ranges of serum TSH, FT4 and thyroid autoantibodies in the Thai population: The national health examination survey. Clin Endocrinol (Oxf), 2014; 80(5):751–756; doi: 10.1111/cen.12371
9.
EskelinenS, SuominenP, VahlbergT, et al.The effect of thyroid antibody positivity on reference intervals for thyroid stimulating hormone (TSH) and free thyroxine (FT4) in an aged population. Clin Chem Lab Med, 2005; 43(12):1380–1385; doi: 10.1515/CCLM.2005.236
10.
VölzkeH, AlteD, KohlmannT, et al.Reference intervals of serum thyroid function tests in a previously iodine-deficient area. Thyroid, 2005; 15(3):279–285; doi: 10.1089/thy.2005.15.279
11.
CaiJ, FangY, JingD, et al.Reference intervals of thyroid hormones in a previously iodine-deficient but presently more than adequate area of Western China: A population-based survey. Endocr J, 2016; 63(4):381–388; doi: 10.1507/endocrj.EJ15-0574
12.
TanRZ, MarkusC, VasikaranS, et al. APFCB Harmonization of Reference Intervals Working Group. Comparison of 8 methods for univariate statistical exclusion of pathological subpopulations for indirect reference intervals and biological variation studies. Clin Biochem, 2022; 103:16–24; doi: 10.1016/j.clinbiochem.2022.02.006
13.
AmmerT, SchützenmeisterA, ProkoschHU, et al. A proposed benchmark for the standardized evaluation of indirect methods for reference interval estimation. Clin Chem, 2022:hvac142; doi: 10.1093/clinchem/hvac142
14.
HollowellJG, StaehlingNW, FlandersWD, et al.Serum TSH, T(4), and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). J Clin Endocrinol Metab, 2002; 87(2):489–499; doi: 10.1210/jcem.87.2.8182
15.
RazviS, RyanV, IngoeL, et al.Age-related serum thyroid-stimulating hormone reference range in older patients treated with levothyroxine: A randomized controlled feasibility trial (SORTED 1). Eur Thyroid J, 2020; 9(1):40–48; doi: 10.1159/000504047
16.
ThienpontLM, Van UytfangheK, De GrandeLAC, et al.IFCC Committee for Standardization of Thyroid Function Tests (C-STFT). Harmonization of serum thyroid-stimulating hormone measurements paves the way for the adoption of a more uniform reference interval. Clin Chem, 2017; 63(7):1248–1260; doi: 10.1373/clinchem.2016.269456
17.
WaiseA, PriceHC. The upper limit of the reference range for thyroid-stimulating hormone should not be confused with a cut-off to define subclinical hypothyroidism. Ann Clin Biochem, 2009; 46(Pt 2):93–98; doi: 10.1258/acb.2008.008113
18.
AndersenS, PedersenKM, BruunNH, et al.Narrow individual variations in serum T(4) and T(3) in normal subjects: A clue to the understanding of subclinical thyroid disease. J Clin Endocrinol Metab, 2002; 87(3):1068–1072; doi: 10.1210/jcem.87.3.8165
19.
SterenborgRBTM, GaleslootTE, TeumerA, et al.The effects of common genetic variation in 96 genes involved in thyroid hormone regulation on TSH and FT4 concentrations. J Clin Endocrinol Metab, 2022; 107(6):e2276–e2283; doi: 10.1210/clinem/dgac136
20.
RothackerKM, BrownSJ, HadlowNC, et al.Reconciling the log-linear and non-log-linear nature of the TSH-free T4 relationship: Intra-individual analysis of a large population. J Clin Endocrinol Metab, 2016; 101(3):1151–1158; doi: 10.1210/jc.2015-4011
21.
HadlowNC, RothackerKM, WardropR, et al.The relationship between TSH and free T4 in a large population is complex and nonlinear and differs by age and sex. J Clin Endocrinol Metab, 2013; 98(7):2936–2943; doi: 10.1210/jc.2012-4223