Suzanne J Brown1, Alexandra P Bremner2, Narelle C Hadlow3, Peter Feddema4, Peter J Leedman5,6,7, Peter C O'Leary8,9, John P Walsh10,5. 1. Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, Australia. Suzanne.Brown@health.wa.gov.au. 2. School of Population Health, The University of Western Australia, Crawley, WA, Australia. 3. Department of Clinical Biochemistry, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Nedlands, WA, Australia. 4. Diagnostica Stago, Doncaster, Vic., Australia. 5. School of Medicine and Pharmacology, The University of Western Australia, Crawley, WA, Australia. 6. UWA Centre for Medical Research, Harry Perkins Institute for Medical Research, Perth, WA, Australia. 7. Department of Endocrinology and Diabetes, Royal Perth Hospital, Perth, WA, Australia. 8. School of Women's and Infants' Health, The University of Western Australia, Crawley, WA, Australia. 9. Curtin Health Innovation Research Institute, Curtin University of Technology, Bentley, WA, Australia. 10. Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.
Abstract
BACKGROUND: 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 log10 TSH 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.
BACKGROUND: 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 log10 TSH 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.
Authors: Rudolf Hoermann; John E M Midgley; Rolf Larisch; Johannes W Dietrich Journal: Front Endocrinol (Lausanne) Date: 2016-11-07 Impact factor: 5.555
Authors: Claudio Schneider; Martin Feller; Douglas C Bauer; Tinh-Hai Collet; Bruno R da Costa; Reto Auer; Robin P Peeters; Suzanne J Brown; Alexandra P Bremner; Peter C O'Leary; Peter Feddema; Peter J Leedman; Drahomir Aujesky; John P Walsh; Nicolas Rodondi Journal: PLoS One Date: 2018-04-30 Impact factor: 3.240
Authors: So Young Park; Hae In Kim; Hyun-Kyung Oh; Tae Hyuk Kim; Hye Won Jang; Jae Hoon Chung; Myung-Hee Shin; Sun Wook Kim Journal: PLoS One Date: 2018-02-01 Impact factor: 3.240
Authors: Rudolf Hoermann; John E M Midgley; Rolf Larisch; Johannes W Dietrich Journal: Front Endocrinol (Lausanne) Date: 2017-12-22 Impact factor: 5.555
Authors: Rudolf Hoermann; John Edward Maurice Midgley; Rolf Larisch; Johannes Wolfgang Christian Dietrich Journal: PLoS One Date: 2017-11-20 Impact factor: 3.240