Abstract:

Objective To explore the association between the risk of high residual cholesterol （RC） and thyroid hormone sensitivity among elderly osteoporosis （OP） women with normal thyroid function. Methods This retrospective study recruited 937 hospitalized female OP patients aged 60 years or older with normal thyroid function from January 2021 to December 2023. Among them， 703 cases were assigned to the normal RC level group （Group A）， whose RC levels were in the lower three quartiles， and 234 cases were assigned to the high RC level group （Group B）， whose RC levels were in the upper quartile. Liver function， kidney function， electrolyte levels， blood lipid profiles， and thyroid function indicators were measured. The FT3/FT4 ratio， thyroid feedback quantile index （TFQI）， thyroid-stimulating hormone thyroid resistance index （TT4RI）， thyroid-stimulating hormone index （TSHI）， and RC were calculated. Binary logistic regression analysis and restricted cubic spline （RCS） were employed to explore the risk factors of high RC in elderly women with osteoporosis and its relationship with thyroid hormone sensitivity. Results （1） When compared with the normal RC level group， the levels of TG， TC， LDL-C， FT4， TFQI， and TSHI in the high RC level group were elevated， whereas the levels of HDL-C and the FT3/FT4 ratio were reduced in the high RC level group compared with group A （P < 0.05）. （2） TFQI and the FT3/FT4 ratio were identified as risk factors for high RC in elderly women with OP， and the odds ratios （ORs） were 1.50 （95%CI： 1.04-2.16） and 0.02 （95%CI： 0.00-0.76）， respectively， with P < 0.05. （3） TFQI stratification analysis indicated that as its level rose， the risk of high RC also increased. In the third stratum， for each unit increase in TFQI， the risk of high RC increased the most， reaching 2.28-fold， with an OR of 2.28 （95%CI： 1.47-3.54）， P < 0.05. （4） Restricted cubic spline analysis revealed an inverted U-shaped correlation between TFQI and RC content， with a cut-off point of 0.304， and an inverted U-shaped relationship with the risk of high RC. When TFQI was between -0.021 and 0.772 （inclusive）， the risk of high RC increased. Conclusion Impaired thyroid hormone sensitivity serves as a risk factor for high RC in elderly women with osteoporosis. The TFQI exhibits an inverse U-shaped correlation with RC content and the risk of high RC.

Key words: thyroid hormone, sensitivity, elderly, women, osteoporosis, residual cholesterol