The non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) is associated with thyroid hormones and thyroid hormone sensitivity indices: a cross-sectional study

Lipids and thyroid hormones (TH) are closely interrelated. However, previous studies have not mentioned the linkage encompassing the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) alongside TH level, as well as sensitivity indices. This cross-sectional study leverages expansive datasets from the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2012. Weighted multivariate linear regression, smoothed curve fitting and sensitivity analyses were used to investigate the associations of the NHHR with the thyroid. Subgroup analyses and interaction tests were conducted to determine the robustness of the findings across diverse segments of the population, ensuring the consistency and generalizability of the observed associations. The NHHR was significantly positively correlated with free triiodothyronine (FT3) levels, thyroid-stimulating hormone (TSH) levels, the FT3 to FT4 ratio (FT3/FT4), and the quantile-based thyroid feedback index for FT3 (TFQI ) and negatively correlated with free thyroxin (FT4) levels [0.17(0.07-0.27), P = 0.001; 0.60 (0.03-1.17), P = 0.040; 0.06 (0.04-0.08), P