open access

Vol 72, No 1 (2021)
Original paper
Submitted: 2020-07-27
Accepted: 2020-09-01
Published online: 2020-09-25
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Free triiodothyronine/free thyroxine (FT3/FT4) ratio is strongly associated with insulin resistance in euthyroid and hypothyroid adults: a cross-sectional study

Ladislav Štěpánek12, Dagmar Horáková1, Lubomír Štěpánek3, Vladimír Janout1, Jana Janoutová4, Kateřina Bouchalová5, Karel Martiník6
·
Pubmed: 33125689
·
Endokrynol Pol 2021;72(1):8-13.
Affiliations
  1. Department of Public Health, Faculty of Medicine and Dentistry, Palacký University Olomouc, Olomouc, Czech Republic
  2. Department of Occupational Medicine, University Hospital Olomouc and Faculty of Medicine and Dentistry, Palacký University Olomouc, Olomouc, Czech Republic
  3. Institute of Biophysics and Informatics, First Faculty of Medicine, Charles University, Prague, Czech Republic
  4. Department of Healthcare Management, Faculty of Health Sciences, Palacký University Olomouc, Olomouc, Czech Republic
  5. Department of Pediatrics, University Hospital Olomouc and Faculty of Medicine and Dentistry, Palacký University Olomouc, Olomouc, Czech Republic
  6. Ambulance Prof. MUDr. Karla Martiníka DrSc. s.r.o, Hradec Králové, Czech Republic

open access

Vol 72, No 1 (2021)
Original Paper
Submitted: 2020-07-27
Accepted: 2020-09-01
Published online: 2020-09-25

Abstract

Introduction: Insulin resistance (IR) is a key and early pathogenetic mechanism of cardiometabolic diseases with huge potential if detected early and mitigated, for lowering the burden of the disease. Available data are conflicting to what extent adult thyroid dysfunction is associated with IR. Therefore, we aimed to investigate the association and to identify which thyroid parameters are predictors of IR.

Material and methods: After undergoing basic anthropometric and biochemical studies including thyroid hormones, oral glucose tolerance test (OGTT), and insulin, 1425 middle-aged individuals were divided into three groups according to thyroid parameters: overt hypothyroidism (OH), subclinical hypothyroidism (SH), and euthyroidism (EU).

Results: The homeostasis model assessment of IR (HOMA-IR), fasting insulin, and two-hour glucose levels of OGTT showed a steady, yet insignificant, increase from EU through SH to OH. The strongest noted correlations were those of insulin levels with free triiodothyronine/free thyroxine (FT3/FT4) ratio (r = 0.206, p < 0.001) and FT3 (r = 0.205, p < 0.001). Also in the case of HOMA-IR, the only statistically significant correlations were observed for FT3 (r = 0.181, p < 0.001) and the FT3/FT4 ratio (r = 0.165, p < 0.001). Among other thyroid hormones, linear logistic regression proved the FT3/FT4 ratio as the only significant predictor of HOMA-IR (linear coefficient = 5.26, p = 0.027) and insulin levels (linear coefficient = 18.01, p = 0.023), respectively. Thyroid-stimulating hormone was not associated with IR in either correlation or regression analysis.

Conclusions: The FT3/FT4 ratio should be more emphasised in the diagnosis and treatment of thyroid disorders. Patients could benefit from a pharmacological reduction of the FT3/FT4 ratio, potentially leading to a decrease in insulin resistance, and thus a corresponding decrease in the risk of the cardiometabolic diseases. 

Abstract

Introduction: Insulin resistance (IR) is a key and early pathogenetic mechanism of cardiometabolic diseases with huge potential if detected early and mitigated, for lowering the burden of the disease. Available data are conflicting to what extent adult thyroid dysfunction is associated with IR. Therefore, we aimed to investigate the association and to identify which thyroid parameters are predictors of IR.

Material and methods: After undergoing basic anthropometric and biochemical studies including thyroid hormones, oral glucose tolerance test (OGTT), and insulin, 1425 middle-aged individuals were divided into three groups according to thyroid parameters: overt hypothyroidism (OH), subclinical hypothyroidism (SH), and euthyroidism (EU).

Results: The homeostasis model assessment of IR (HOMA-IR), fasting insulin, and two-hour glucose levels of OGTT showed a steady, yet insignificant, increase from EU through SH to OH. The strongest noted correlations were those of insulin levels with free triiodothyronine/free thyroxine (FT3/FT4) ratio (r = 0.206, p < 0.001) and FT3 (r = 0.205, p < 0.001). Also in the case of HOMA-IR, the only statistically significant correlations were observed for FT3 (r = 0.181, p < 0.001) and the FT3/FT4 ratio (r = 0.165, p < 0.001). Among other thyroid hormones, linear logistic regression proved the FT3/FT4 ratio as the only significant predictor of HOMA-IR (linear coefficient = 5.26, p = 0.027) and insulin levels (linear coefficient = 18.01, p = 0.023), respectively. Thyroid-stimulating hormone was not associated with IR in either correlation or regression analysis.

Conclusions: The FT3/FT4 ratio should be more emphasised in the diagnosis and treatment of thyroid disorders. Patients could benefit from a pharmacological reduction of the FT3/FT4 ratio, potentially leading to a decrease in insulin resistance, and thus a corresponding decrease in the risk of the cardiometabolic diseases. 

Get Citation

Keywords

thyroid disorder; insulin resistance; FT3/FT4 ratio; hypothyroidism; euthyroidism

About this article
Title

Free triiodothyronine/free thyroxine (FT3/FT4) ratio is strongly associated with insulin resistance in euthyroid and hypothyroid adults: a cross-sectional study

Journal

Endokrynologia Polska

Issue

Vol 72, No 1 (2021)

Article type

Original paper

Pages

8-13

Published online

2020-09-25

Page views

2983

Article views/downloads

1621

DOI

10.5603/EP.a2020.0066

Pubmed

33125689

Bibliographic record

Endokrynol Pol 2021;72(1):8-13.

Keywords

thyroid disorder
insulin resistance
FT3/FT4 ratio
hypothyroidism
euthyroidism

Authors

Ladislav Štěpánek
Dagmar Horáková
Lubomír Štěpánek
Vladimír Janout
Jana Janoutová
Kateřina Bouchalová
Karel Martiník

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