Endogenous cortisol and lung damage in a predominantly smoking population

We examined the association of endogenous corticosteroid status with lung structure and function in a cross-sectional and longitudinal study in response to a recent finding of a relationship between plasma cortisol and rate of annual decline in airway function. We recruited 74 cigarette-smoking and 20 never-smoking volunteers 35 to 65 yr of age after publicity in local media. Exclusion criteria were FEV1 < 1.5 L or a history of airway disease. We performed spirometry and a high resolution CT lung scan and measured CO transfer, serum cortisol, and 24-h urinary cortisol excretion. There were no differences in serum or urinary cortisol between those with and those without low FEV1, low KCO, or high resolution CT (HRCT) emphysema, except that urinary cortisol was 19% higher in subjects with HRCT emphysema (p = 0.05). Log urinary cortisol/body weight was negatively correlated with KCO (p = 0.000) and KCO was lower in the highest tertile of urinary cortisol (p = 0.001). Subjects were restudied after 520 +/- 69 d. Changes in FEV1 and KCO showed no significant correlations with serum or urinary cortisol. We conclude that airway function does not relate to serum or urinary cortisol, but there may be a relationship between cortisol excretion and emphysema.