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 52 publications

(46 citation statements)

References 38 publications

(116 reference statements)

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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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Thyroid function in Klinefelter syndrome: a multicentre study from KING group

Balercia

Bonomi

Giagulli³

et al. 2019

J Endocrinol Invest

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The prevalence and the etiopathogenesis of thyroid dysfunctions in Klinefelter syndrome (KS) are still unclear. The primary aim of this study was to evaluate the pathogenetic role of hypogonadism in the thyroid disorders described in KS, with the scope to distinguish between genetic alterations or hormonal involvement. Therefore, we evaluated thyroid function in KS and in non-KS hypogonadal patients. Methods This is a case-control multicentre study from KING group: Endocrinology clinics in university-affiliated medical centres. One hundred seventy four KS, and sixty-two non-KS hypogonadal men were enrolled. The primary outcome was the prevalence of thyroid diseases in KS and in non-KS. Changes in hormonal parameters were evaluated. Exclusion criterion was secondary hypothyroidism. Analyses were performed using Student's t test. Mann-Whitney test and chi-square test. Results FT4 was significantly lower in KS vs non-KS. KS and non-KS presented similar TSH and testosterone levels. Hashimoto's thyroiditis (HT) was diagnosed in 7% of KS. Five KS developed hypothyroidism. The ratio FT3/FT4 was similar in both groups. TSH index was 1.9 in KS and 2.3 in non-KS. Adjustment for differences in age, sample size and concomitant disease in multivariate models did not alter the results. Conclusions We demonstrated in KS no etiopathogenic link to hypogonadism or change in the set point of thyrotrophic control in the altered FT4 production. These results suggest possible deiodinase impairment. The prevalence of HT in KS was similar to normal male population, showing absence of increased risk of HT associated with the XXY karyotype.

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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 52 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?

Thyroid function in Klinefelter syndrome: a multicentre study from KING group

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