Free triiodothyronine/free thyroxine ratio rather than thyrotropin is more associated with metabolic parameters in healthy euthyroid adult subjects

Park, So Young; Park, Se Eun; Jung, Sang Won; Jin, Hyun‐Seok; Park, Ie Byung; Ahn, Song Vogue; Lee, Sihoon

doi:10.1111/cen.13345

Cited by 61 publications

(57 citation statements)

References 38 publications

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“…White adipose tissue is known to possess endocrine functions, producing various hormones, cytokines and chemokines . Previous studies evaluating the associations between thyroid hormones and obesity in euthyroid subjects reported that serum TSH and FT3 levels were positively associated with BMI and WC . Few studies evaluating the association between thyroid hormone levels and obesity have used body fat mass and BFP as obesity metrics .…”

Section: Discussionmentioning

confidence: 99%

“…7,8 Previous studies evaluating the associations between thyroid hormones and obesity in euthyroid subjects reported that serum TSH and FT3 levels were positively associated with BMI and WC. 9,11,12,14,15 Few studies evaluating the association between thyroid hormone levels and obesity have used body fat mass and BFP as obesity metrics. 5,21 Body composition including body fat mass and BFP can reflect the amount of adipose tissue more accurately than BMI and WC.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, the changes in body composition might influence thyroid hormone levels. Previous studies have evaluated the associations between thyroid hormone levels and anthropometric markers . Serum thyrotropin (thyroid‐stimulating hormone, TSH), triiodothyronine (T3) and free T3 (FT3) levels were positively associated with body mass index (BMI) and waist circumference (WC) in euthyroid subjects .…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have evaluated the associations between thyroid hormone levels and anthropometric markers. 4,5,[9][10][11][12][13][14][15][16][17][18][19][20] Serum thyrotropin (thyroid-stimulating hormone, TSH), triiodothyronine (T3) and free T3 (FT3) levels were positively associated with body mass index (BMI) and waist circumference (WC) in euthyroid subjects. 11,12,14,15 However, the associations of serum thyroxine (T4) and free T4 (FT4) levels with obesity are controversial.…”

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confidence: 99%

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Association between thyroid hormone levels, body composition and insulin resistance in euthyroid subjects with normal thyroid ultrasound: The Kangbuk Samsung Health Study

Kwon

Cho

Lee

et al. 2018

Clinical Endocrinology

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Association between thyroid hormone levels, body composition and insulin resistance in euthyroid subjects with normal thyroid ultrasound: The Kangbuk Samsung Health Study

Kwon

Cho

Lee

et al. 2018

Clinical Endocrinology

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“…The study of the free triiodothyronine/free thyroxine (FT3/FT4) ratio appears to be important, in view of recent research showing that this ratio may be an important predictor of metabolic disease [1].…”

Section: Introductionmentioning

confidence: 99%

Levothyroxine Therapy Achieves Physiological FT3/FT4 Ratios at Higher than Normal TSH Levels: A Novel Justification for T3 Supplementation?

et al. 2018

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In euthyroidism, as thyroid Stimulating hormone (TSH) levels increase, the free triiodothyronine (FT3) to free thyroxine (FT4) ratio increases. The aim of this study was to assess if beyond the euthyroid range of TSH levels FT3/FT4 ratio continues to increase and if levothyroxine treatment reduces this ratio, possibly through TSH suppression. This cross sectional retrospective study included a total of 77 832 patients [age 22.76±15.17 years (4 days to 112 years)] evaluated and treated in community clinics between January 2009 and September 2013. Blood samples drawn in community clinics for which TSH, FT4, FT3, age, and gender were available were included. Tests with TSH below 0.5 IU/l were excluded as were samples taken during pregnancy. The FT3/FT4 ratio continued to increase significantly even with TSH above 50 mIU/l (p for trend<0.001) with an increase of more than 50% over the entire TSH range. With increasing age and female gender, the phenomenon was less prominent (p<0.001). Levothyroxine treated patients had significantly lower FT3/FT4 ratios in comparison to untreated patients up to TSH levels of 5.0 mIU/l. In conclusion, increasing TSH increases FT3/FT4 ratio even with severe hypothyroidism, less so with aging. With levothyroxine therapy, a ratio similar to untreated patients is achieved at TSH of above 5.0 mIU/l. Since T3 suppresses TSH better than T4, administration of T3 would likely normalize the FT3/FT4 ratio at a lower, ostensibly more physiological, TSH level. This could be seen as a rationale for add-on T3 therapy.

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Central and Peripheral Sensitivity to Thyroid Hormones Correlate to Metabolically Obesity Phenotypes in Chinese Euthyroid Adults: A Cross‐Sectional Study

Lu,

Ye,

et al. 2024

Diabetes Metabolism Res

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AimsThyroid hormones impact lipid metabolism and glucose homoeostasis through both central and peripheral regulation; however, little research has delved into the association between thyroid hormone sensitivity and metabolically obese phenotypes. We aimed to investigate the correlation between indices of central and peripheral sensitivity to thyroid hormones and metabolically obese phenotypes in euthyroid Chinese adults.MethodsThis cross‐sectional study included 20,084 euthyroid individuals. Central thyroid hormone sensitivity was assessed using the thyroid feedback quantile‐based index (TFQI), parametric thyroid feedback quantile‐based index (PTFQI), thyroid‐stimulating hormone index (TSHI), and thyrotropin thyroxine resistance index (TT4RI), while peripheral thyroid hormone sensitivity was measured by FT3/FT4. Metabolically obesity phenotypes included metabolically healthy non‐obesity (MHNO), unhealthy non‐obesity (MUNO), metabolically healthy obesity (MHO), and unhealthy obesity (MUO). Multinomial logistic regression and restricted cubic spline analyses were conducted to investigate the association between thyroid hormone sensitivity indices and metabolically obese phenotypes risk. Subgroup analysis was also performed to examine this association stratified by sex and age. Mediation analysis was performed to estimate direct and indirect effects of BMI.ResultsPrevalence of MHNO, MUNO, MHO and MUO was 66.1% (n = 13,273), 21.3% (n = 4271), 5.3% (n = 1055), and 7.4% (n = 1485) respectively. After adjustment for potential confounders, the odds ratios (ORs) (95% CI) for MUNO and MUO were increased with all elevated thyroid hormones sensitivity indices (per SD increase) [MUNO: TFQI 1.14(1.09–1.19), PTFQI 1.18(1.23–1.23); TSHI 1.26(1.19–1.33), TT4RI 1.41, (1.31–1.53), FT3/FT4 1.20(1.14–1.25) and [MUO: TFQI 1.20(1.11–1.31), PTFQI 1.26(1.16–1.37), TSHI 1.39 (1.26–1.54), TT4RI 1.70(1.48–1.95), FT3/FT4 1.26 (1.16–1.37)] (p value < 0.001), and only TSHI and TT4RI (per SD increase) significantly increased the risk of MHO (TSHI: OR = 1.12, 95% CI 1.01–1.24; TT4RI: OR = 1.25, 95%CI 1.08–1.4) (p value < 0.05). Non‐linear relationships were observed between central thyroid hormones sensitivity indices and MUNO and MUO(p for nonlinearity < 0.05). Conversely, a linear relationship between FT3/FT4 and metabolically obese phenotypes was noted in all subjects (p for nonlinearity > 0.05). Besides, subgroup analysis indicated that this association remained consistent among sex and age (p for interaction > 0.05). The proportions mediated by BMI on the association of TFQI, PTFQI, TSHI, TT4RI, FT3/FT4 and risk of metabolically unhealthy conditions were 13.73%, 25.38%, 22.75%, 17.94% and 62.28%, respectively.ConclusionsIn euthyroid adults, central and peripheral sensitivity to thyroid hormones indices are positively associated with metabolically obese phenotypes risk, especially MUNO and MUO phenotypes.

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Free triiodothyronine/free thyroxine ratio rather than thyrotropin is more associated with metabolic parameters in healthy euthyroid adult subjects

Abstract: Thyrotropin levels were positively associated with FT3/FT4 ratio within the euthyroid range. The higher FT3/FT4 ratio is associated with increased risk of metabolic syndrome parameters and insulin resistance. FT3/FT4 ratio has a better predictive power for metabolic syndrome than TSH.

Cited by 61 publications

References 38 publications

Association between thyroid hormone levels, body composition and insulin resistance in euthyroid subjects with normal thyroid ultrasound: The Kangbuk Samsung Health Study

Association between thyroid hormone levels, body composition and insulin resistance in euthyroid subjects with normal thyroid ultrasound: The Kangbuk Samsung Health Study

Levothyroxine Therapy Achieves Physiological FT3/FT4 Ratios at Higher than Normal TSH Levels: A Novel Justification for T3 Supplementation?

Central and Peripheral Sensitivity to Thyroid Hormones Correlate to Metabolically Obesity Phenotypes in Chinese Euthyroid Adults: A Cross‐Sectional Study

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