Impaired sensitivity to thyroid hormones is associated with increased body fat mass/muscle mass ratio (F/M) in the
Ying Li1, Qianqian Zhang1, Li Chen1
1Department of Endocrinology, The First People's Hospital of Hefei, No. 3200, Changsha Road, Binhu New District, Hefei, 230001, Anhui, China.
Objective:
To explore the relationship between body fat mass/muscle mass ratio (F/M) and thyroid hormone sensitivity in the euthyroid population.
Methods:
Body compositions of 845 check-up individuals were determined using bioelectrical impedance analysis (BIA). Biochemical indexes including blood glucose, blood lipids, liver and kidney functions and thyrotropic hormones (THs) were detected. Free triiodothyronine to free thyroxine ratio (FT3/FT4), Thyroid Feedback Quantile-based Index (TFQI), Thyrotropin Thyroxine Resistance Index (TT4RI) and TSH Index (TSHI) were calculated for analysis.
Results:
TT4RI and TSHI showed increased trends with statistical difference, while FT3/FT4 and TFQI showed no difference among F/M quartile groups. After adjusting for confounding factors, F/M exhibited no correlation with FT3/FT4, but positive correlations with TFQI, TT4RI and TSHI. Gender subgroup analysis showed that F/M exhibited positive relationship with TFQI in females; exhibited positive correlations with TFQI, TT4RI and TSHI before the inflection points, but no correlations thereafter in males. Age subgroup analysis showed that F/M exhibited positive correlations with TFQI, TT4RI and TSHI, but no correlation with FT3/FT4 in age < 65 years group; exhibited no relationship with thyroid hormone sensitivity in age ≥ 65 years group. BMI subgroup analysis showed that F/M exhibited no relationship with thyroid hormone sensitivity in BMI < 25 kg/m2 group; exhibited positive correlations with TFQI, TT4RI and TSHI before the inflection points, but no correlations thereafter in BMI ≥ 25, < 30 kg/m2 group; exhibited positive correlation with TFQI before the inflection point, but no correlation thereafter in BMI ≥ 30 kg/m2 group; exhibited no correlations with TT4RI and TSHI before the inflection points, but negative correlations with them thereafter in BMI ≥ 30 kg/m2 group.
Conclusion:
Impaired central, but not peripheral sensitivity to thyroid hormones was associated with increased body fat mass/muscle mass ratio (F/M), this association was obvious in males, individuals with age < 65 years and BMI ≥ 25 kg/m2, with different inflection points. Maybe F/M independently affects thyroid hormone sensitivity, we need more clinical and basic studies in the future.
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