Association between asthma and thyroid function as well as thyroid hormone sensitivity indicators: an NHANES study

Area of Science:

• Endocrinology
• Pulmonology
• Epidemiology

Background:

• Thyroid hormones are crucial for physiological functions, including the respiratory system.
• Emerging evidence suggests a potential link between asthma and thyroid function.
• Limited research exists on the specific associations between asthma, thyroid hormones, and thyroid hormone sensitivity.

Purpose of the Study:

• To investigate the relationship between asthma, thyroid function, and thyroid hormone sensitivity in U.S. adults.
• To analyze associations using data from the National Health and Nutrition Examination Survey (NHANES).
• To explore potential correlations between thyroid parameters and asthma risk.

Main Methods:

• Utilized weighted analyses of NHANES 2007-2012 data (n=8160).
• Assessed thyroid function (FT3, FT4, TSH, etc.) and sensitivity indices (FT3/FT4 ratio, TT4RI, TSHI, TFQI).
• Conducted subgroup analyses, ROC curve investigations, and institutional validation with a retrospective cohort.

Main Results:

• Asthmatics showed higher free triiodothyronine (FT3) and FT3/FT4 ratios but lower thyroid peroxidase antibody (TPOAb) levels.
• Adjusted models indicated an inverse association between asthma risk and the FT3/FT4 ratio.
• Institutional validation suggested lower FT3 levels in asthma patients, with a trend towards fewer exacerbations at higher FT3 levels.

Conclusions:

• FT3 and FT3/FT4 levels may be inversely correlated with asthma risk.
• The observed associations warrant further investigation due to the cross-sectional study design.
• Causality between thyroid hormone levels and asthma remains undetermined.