Association between sensitivity to thyroid hormone indices and the risk of subclinical kidney damage in euthyroid adults: an NHANES Study (2007-2010) from United States

Abstract

Abstract Objectives subclinical kidney damage (SKD) and thyroid diseases are both common clinical diseases that lead to multi-system organ disfunction, and the relationship between the two diseases and their detailed mechanism have not been well described. This study aims to explore the correlation between thyroid function and SKD from a new perspective of sensitivity to thyroid hormone. Methods A total of 3451 United States euthyroid adults were included and divided according to quartiles of sensitivity to thyroid hormone indices from the National Health and Nutrition Examination Survey (NHANES) 2007–2010. Thyroid Feedback Quantile-based Index (TFQI), Thyrotroph Thyroxine Resistance Index (TT4RI, Thyroid-stimulating hormone (TSHI), and Free Triiodothyronine /Free thyroxine (FT3/FT4) represent the sensitivity of Hypothalamus-pituitary-Thyroid (HPT) axis and peripheral tissue to thyroid hormone, respectively. We apply logistic regression to analyze the associations between those indices with SKD. Results Subjects with SKD had elevated TSHI, TT4RI, and TFQI levels, and lower FT3/FT4 levels compared to those without SKD. Logistic regression analyses showed that higher TSHI, TT4RI, and TFQI levels were positively with SKD, but FT3/FT4 was negatively associated with the risk of SKD. In subgroup analyses stratified by gender and age, the associations between sensitivity to thyroid hormones and SKD were more obvious in men than in women and in age < = 65 years old than in age > 65 years old(P < 0.05). FT3/FT4 ratio performed better than TFQI, TSHI, and TT4RI on ROC analyses for SKD prediction. When thyroid parameters are categorized into quartiles, we found an interesting a “Simpson’s Paradox” phenomenon between sensitivity to thyroid hormone indices and SKD in the logistic regression analysis. Conclusion Impaired sensitivity to thyroid hormones was associated with SKD in United States euthyroid adults which illustrates the correlation between the thyroid system and SKD.