Correlation between serum iron levels and pulmonary function: A cross-sectional analysis based on NHANES database...

Area of Science:

• Pulmonary Medicine
• Nutritional Science
• Epidemiology

Background:

• Pulmonary function is a critical indicator of respiratory health.
• Assessing pulmonary function can be challenging in certain populations.
• The relationship between serum iron levels and lung function requires further investigation.

Purpose of the Study:

• To investigate the association between serum iron levels and pulmonary function indicators.
• To explore the nature of this relationship, including potential non-linear effects and thresholds.

Main Methods:

• A cross-sectional study utilizing data from 5319 participants in the National Health and Nutrition Examination Survey (2010-2012).
• Pulmonary function was assessed using forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and forced expiratory flow from 25% to 75% of FVC.
• Statistical analyses included univariate, stratified, multiple regression, smoothed curve fitting, and threshold effect analyses.

Main Results:

• A nonlinear relationship was observed between serum iron levels and FVC/FEV1, with identified inflection points at 8.1 µmol/L and 8.4 µmol/L, respectively.
• Below these thresholds, serum iron showed no significant association with FVC or FEV1.
• Above the inflection points, increased serum iron levels were positively correlated with FVC (β=6.87) and FEV1 (β=7.09).
• Forced expiratory flow from 25% to 75% of FVC also showed a positive association with serum iron (β=6.72).

Conclusions:

• Serum iron levels are positively correlated with pulmonary function within specific concentration ranges.
• Elevated serum iron levels, exceeding identified thresholds, are associated with improved lung function.
• Serum iron may act as a protective factor for maintaining pulmonary function.