The log TSH-free T4 relationship in a community-based cohort is nonlinear and is influenced by age, smoking and thyroid peroxidase antibody status.

S.J. Brown, Alex Bremner, N.C. Hadlow, P. Feddema, Peter Leedman, Peter O'Leary, John Walsh

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

© 2016 John Wiley & Sons LtdBackground: The TSH–T4 relationship was thought to be inverse log-linear, but recent cross-sectional studies of selected populations report a complex, nonlinear relationship. The TSH–T4 relationship has not been evaluated in an unselected, community-based cohort, and there are limited data regarding clinical factors which affect it. Objective: To analyse the TSH–free T4 relationship in a community-based cohort. Design, participants and methods: In a cross-sectional, retrospective study, we analysed serum TSH and free T4 concentrations from 4427 participants (55% female) in the 1994 Busselton Health Study who were not taking thyroxine. Simple linear, segmented-linear and nonlinear regression models of log10TSH on free T4 were compared for goodness of fit. Results: All 5 log TSH–free T4 models tested (separate lines, segmented conterminal line, quartic, error function, double-sigmoid curve) fitted significantly better than a simple linear model (each P <0·01 by Vuong test). Ranking by Akaike information criterion indicated that the segmented conterminal line and double-sigmoid models provided best fit, followed by the error function, quartic and separate lines models. From multiple regression analysis, age tertile, current smoking and TPOAb status each significantly influenced the TSH–free T4 relationship, whereas BMI category and diabetes did not. A sex difference in the TSH–free T4 relationship was apparent only in the lower part of the free T4 reference range. Conclusion: In a community-based setting, the relationship between log TSH and free T4 is complex, nonlinear and influenced by age, smoking and TPOAb status.
Original languageEnglish
Pages (from-to)789-796
JournalClinical Endocrinology
Volume85
Issue number5
DOIs
Publication statusPublished - Nov 2016

Fingerprint

Iodide Peroxidase
Smoking
Sigmoid Colon
Antibodies
Linear Models
Cross-Sectional Studies
Nonlinear Dynamics
Thyroxine
Sex Characteristics
Reference Values
Retrospective Studies
Regression Analysis
Health
Serum
Population

Cite this

@article{7c7623e9df524b81905b86c08d406c1c,
title = "The log TSH-free T4 relationship in a community-based cohort is nonlinear and is influenced by age, smoking and thyroid peroxidase antibody status.",
abstract = "{\circledC} 2016 John Wiley & Sons LtdBackground: The TSH–T4 relationship was thought to be inverse log-linear, but recent cross-sectional studies of selected populations report a complex, nonlinear relationship. The TSH–T4 relationship has not been evaluated in an unselected, community-based cohort, and there are limited data regarding clinical factors which affect it. Objective: To analyse the TSH–free T4 relationship in a community-based cohort. Design, participants and methods: In a cross-sectional, retrospective study, we analysed serum TSH and free T4 concentrations from 4427 participants (55{\%} female) in the 1994 Busselton Health Study who were not taking thyroxine. Simple linear, segmented-linear and nonlinear regression models of log10TSH on free T4 were compared for goodness of fit. Results: All 5 log TSH–free T4 models tested (separate lines, segmented conterminal line, quartic, error function, double-sigmoid curve) fitted significantly better than a simple linear model (each P <0·01 by Vuong test). Ranking by Akaike information criterion indicated that the segmented conterminal line and double-sigmoid models provided best fit, followed by the error function, quartic and separate lines models. From multiple regression analysis, age tertile, current smoking and TPOAb status each significantly influenced the TSH–free T4 relationship, whereas BMI category and diabetes did not. A sex difference in the TSH–free T4 relationship was apparent only in the lower part of the free T4 reference range. Conclusion: In a community-based setting, the relationship between log TSH and free T4 is complex, nonlinear and influenced by age, smoking and TPOAb status.",
keywords = "TSH, T4, thyroid",
author = "S.J. Brown and Alex Bremner and N.C. Hadlow and P. Feddema and Peter Leedman and Peter O'Leary and John Walsh",
year = "2016",
month = "11",
doi = "10.1111/cen.13107",
language = "English",
volume = "85",
pages = "789--796",
journal = "Clinical Endocrinology",
issn = "0300-0664",
publisher = "John Wiley & Sons",
number = "5",

}

The log TSH-free T4 relationship in a community-based cohort is nonlinear and is influenced by age, smoking and thyroid peroxidase antibody status. / Brown, S.J.; Bremner, Alex; Hadlow, N.C.; Feddema, P.; Leedman, Peter; O'Leary, Peter; Walsh, John.

In: Clinical Endocrinology, Vol. 85, No. 5, 11.2016, p. 789-796.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The log TSH-free T4 relationship in a community-based cohort is nonlinear and is influenced by age, smoking and thyroid peroxidase antibody status.

AU - Brown, S.J.

AU - Bremner, Alex

AU - Hadlow, N.C.

AU - Feddema, P.

AU - Leedman, Peter

AU - O'Leary, Peter

AU - Walsh, John

PY - 2016/11

Y1 - 2016/11

N2 - © 2016 John Wiley & Sons LtdBackground: The TSH–T4 relationship was thought to be inverse log-linear, but recent cross-sectional studies of selected populations report a complex, nonlinear relationship. The TSH–T4 relationship has not been evaluated in an unselected, community-based cohort, and there are limited data regarding clinical factors which affect it. Objective: To analyse the TSH–free T4 relationship in a community-based cohort. Design, participants and methods: In a cross-sectional, retrospective study, we analysed serum TSH and free T4 concentrations from 4427 participants (55% female) in the 1994 Busselton Health Study who were not taking thyroxine. Simple linear, segmented-linear and nonlinear regression models of log10TSH on free T4 were compared for goodness of fit. Results: All 5 log TSH–free T4 models tested (separate lines, segmented conterminal line, quartic, error function, double-sigmoid curve) fitted significantly better than a simple linear model (each P <0·01 by Vuong test). Ranking by Akaike information criterion indicated that the segmented conterminal line and double-sigmoid models provided best fit, followed by the error function, quartic and separate lines models. From multiple regression analysis, age tertile, current smoking and TPOAb status each significantly influenced the TSH–free T4 relationship, whereas BMI category and diabetes did not. A sex difference in the TSH–free T4 relationship was apparent only in the lower part of the free T4 reference range. Conclusion: In a community-based setting, the relationship between log TSH and free T4 is complex, nonlinear and influenced by age, smoking and TPOAb status.

AB - © 2016 John Wiley & Sons LtdBackground: The TSH–T4 relationship was thought to be inverse log-linear, but recent cross-sectional studies of selected populations report a complex, nonlinear relationship. The TSH–T4 relationship has not been evaluated in an unselected, community-based cohort, and there are limited data regarding clinical factors which affect it. Objective: To analyse the TSH–free T4 relationship in a community-based cohort. Design, participants and methods: In a cross-sectional, retrospective study, we analysed serum TSH and free T4 concentrations from 4427 participants (55% female) in the 1994 Busselton Health Study who were not taking thyroxine. Simple linear, segmented-linear and nonlinear regression models of log10TSH on free T4 were compared for goodness of fit. Results: All 5 log TSH–free T4 models tested (separate lines, segmented conterminal line, quartic, error function, double-sigmoid curve) fitted significantly better than a simple linear model (each P <0·01 by Vuong test). Ranking by Akaike information criterion indicated that the segmented conterminal line and double-sigmoid models provided best fit, followed by the error function, quartic and separate lines models. From multiple regression analysis, age tertile, current smoking and TPOAb status each significantly influenced the TSH–free T4 relationship, whereas BMI category and diabetes did not. A sex difference in the TSH–free T4 relationship was apparent only in the lower part of the free T4 reference range. Conclusion: In a community-based setting, the relationship between log TSH and free T4 is complex, nonlinear and influenced by age, smoking and TPOAb status.

KW - TSH, T4, thyroid

U2 - 10.1111/cen.13107

DO - 10.1111/cen.13107

M3 - Article

VL - 85

SP - 789

EP - 796

JO - Clinical Endocrinology

JF - Clinical Endocrinology

SN - 0300-0664

IS - 5

ER -