Free triiodothyronine/free thyroxine (FT3/FT4) ratio is strongly associated with insulin resistance in euthyroid and hypothyroid adults: a cross-sectional study
Language English Country Poland Media print-electronic
Document type Journal Article
PubMed
33125689
DOI
10.5603/ep.a2020.0066
PII: VM/OJS/J/70164
Knihovny.cz E-resources
- Keywords
- FT3/FT4 ratio, euthyroidism, hypothyroidism, insulin resistance, thyroid disorder,
- MeSH
- Hypothyroidism metabolism MeSH
- Insulin Resistance physiology MeSH
- Middle Aged MeSH
- Humans MeSH
- Cross-Sectional Studies MeSH
- Risk Factors MeSH
- Thyroid Function Tests MeSH
- Thyroxine blood MeSH
- Triiodothyronine blood MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Thyroxine MeSH
- Triiodothyronine MeSH
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.
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