Testosterone-to-estradiol ratio and lung function in a prospective study of Puerto Rican youth

Age- and sex-related differences in asthma may be due to changes in sex hormone levels.

To evaluate whether a change in free testosterone or free testosterone-to-estradiol ratio is associated with changes in lung function and eosinophils in the Puerto Rican youth.

We tested for the association between the change in sex hormone levels and change in lung function or change in eosinophils in a prospective study of 317 children (with and without asthma) followed up from ages 6 to 14 years to ages 10 to 20 years (146 females, 171 males) in San Juan, Puerto Rico. Serum levels of testosterone, estradiol, sex hormone-binding globulin, and progesterone were measured at 2 study visits, approximately 4.9 years apart. Using testosterone and sex hormone-binding globulin levels, we derived free testosterone and the free testosterone-to-estradiol ratio. Multivariable linear regression was used for the analysis of change in lung function and eosinophils, conducted separately by sex.

In girls, each quartile increment in the free testosterone-to-estradiol ratio was associated with a 2.03% increment in percent predicted forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC) between study visits. In males, each quartile increment in the free testosterone-to-estradiol ratio was associated with a 3.27% increment in percent predicted FEV₁ and a 1.81% increment in percent predicted FEV₁/FVC between study visits. In girls with asthma, an increased free testosterone-to-estradiol ratio was significantly associated with decreased eosinophils between visits (P=0.03).

In Puerto Rican youth, increased free testosterone-to-estradiol ratio over time was associated with an increased FEV₁/FVC in both sexes, and with an increased FEV₁ in males.