Association of free thyroxine with obstructive lung pattern in euthyroid middle-aged subjects: A population-based...

Area of Science:

• Endocrinology and Pulmonology
• Population Health Studies

Background:

• The relationship between thyroid hormone levels and lung function in euthyroid individuals remains under-investigated.
• This study addresses the unclear association between thyroid function and pulmonary health in a euthyroid population.

Purpose of the Study:

• To investigate the association between thyroid function, specifically free thyroxine (fT4) levels, and lung function in a large cohort of euthyroid subjects.
• To determine if thyroid hormone levels are predictive of obstructive lung patterns in middle-aged adults.

Main Methods:

• Analysis of biochemical and spirometry data from 1,261 euthyroid middle-aged participants (45-65 years) from the KNHANES VI cross-sectional survey.
• Participants were categorized into quartiles based on free thyroxine (fT4) levels.
• Logistic regression models were used to assess the probability of obstructive lung patterns (defined as FEV1/FVC <0.7), adjusted for confounders.

Main Results:

• 10.9% of participants exhibited an obstructive lung pattern.
• Mean fT4 levels were significantly higher in individuals with obstructive lung patterns compared to those with normal lung function (1.26 vs. 1.20 ng/dL, p<0.001).
• The prevalence of obstructive lung patterns increased across higher fT4 quartiles, with significantly elevated odds ratios for Q3 (2.875) and Q4 (2.970) compared to Q1.

Conclusions:

• Elevated free thyroxine (fT4) levels are an independent predictor of obstructive lung patterns in euthyroid middle-aged individuals.
• These findings suggest a potential link between higher thyroid hormone levels and impaired lung function.
• Further prospective research is warranted to validate these results and elucidate the underlying mechanisms.