Association between the Systemic Immune-Inflammation Index and Thyroid Function in U.S. Adults

Area of Science:

• Endocrinology and Metabolism
• Immunology
• Public Health and Epidemiology

Background:

• The systemic immune-inflammation index (SII) is a prognostic indicator across various diseases.
• Thyroid function is closely linked to inflammatory processes.
• Understanding the relationship between SII and thyroid function is crucial for disease management.

Purpose of the Study:

• To investigate the correlation between the systemic immune-inflammation index (SII) and thyroid function parameters.
• To determine if SII can serve as a predictive marker for thyroid dysfunction.

Main Methods:

• Utilized data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012.
• Employed weighted univariate and multivariate linear regression analyses to assess the SII-thyroid function association.
• Conducted subgroup analyses, interaction tests, and weighted restricted cubic spline (RCS) regression for comprehensive evaluation.

Main Results:

• Analysis of 6,875 participants revealed significant correlations between lnSII and thyroid hormones.
• lnSII showed a negative correlation with free triiodothyronine (FT3) and the FT3/FT4 ratio.
• A positive correlation was observed between lnSII and total thyroxine (TT4), with a nonlinear relationship noted for FT3.

Conclusions:

• Significant associations exist between SII and various thyroid function markers.
• SII demonstrates potential as an indicator for predicting thyroid dysfunction.
• Inflammation control may play a protective role against thyroid dysfunction; further research is warranted.