Impaired central sensitivity to thyroid hormones is associated with increased liver fibrosis degree in the euthyroid population

To analyse the relationship between central sensitivity to thyroid hormones (THs) and liver fibrosis in a euthyroid population. Central TH sensitivity indices, including the thyroid feedback quantile-based index (TFQI), thyroid stimulating hormone index (TSHI), and thyrotropin thyroxine resistance index (TT4RI), were calculated according to TH levels. Liver stiffness measurement (LSM) values were determined by liver shear wave quantification ultrasonography, and statistical analysis of the above data was conducted. Compared with those in the LSM < 7.3 kPa group, the TFQI, TSHI, and TT4RI in the LSM ≥ 7.3 kPa group significantly increased (P < 0.001). Trend tests of multiple regression equations indicated that the LSM was positively correlated with the TT4RI (β = 0.413, P < 0.001). In the sex subgroups, the LSM was positively correlated with the TT4RI (β = 0.425, P = 0.03) and TSHI (β = 0.015, P = 0.027) in females; in the age subgroups, the LSM was positively correlated with the TT4RI (inflection point: 8.4 kPa, β = 0.324, P = 0.01) and TSHI (inflection point: 8.3 kPa, β = 0.01, P = 0.022) before the inflection points in the age < 65 years group; and in the BMI subgroups, the LSM was positively correlated with the TT4RI (inflection point: 5.9 kPa, β = 0.437, P = 0.008), TSHI (inflection point: 6.8 kPa, β = 0.013, P = 0.008) and TFQI (inflection point: 6.8 kPa, β = 0.007, P = 0.045) in the BMI < 30 kg/m² group. Central TH sensitivity decreases as the degree of fibrosis increases in the euthyroid population, particularly among females, individuals aged < 65 years, and those with a BMI < 30 kg/m² within certain ranges.