Airway Size Before And After Gender Affirming Hormone Therapy In Transgender Persons

It is well established females have smaller airways than males, even when matched for height. This sex difference in airway size occurs during puberty, when there is a divergence in endogenous sex hormone concentrations between males and females. Transgender persons often use gender-affirming hormone therapy (GAHT), which includes either masculinizing or feminizing hormone therapy, to align their physical characteristics with their gender identity. It is unknow whether GAHT influences airway size. PURPOSE: To evaluate the sizes of the large conducting airways in individuals before starting GAHT, and while undergoing years of GAHT. METHODS: This was a retrospective, within-subject study that utilized medical records of adult transgender patients. From a cohort of 680 transgender persons, we identified 14 transgender persons (5 on masculinizing hormone therapy, 9 on feminizing hormone therapy) who had a computed tomography (CT) scan taken before beginning GAHT and a CT scan after 1 or more years on GAHT. We used a 3-dimensional reconstruction of CT imaging to measure luminal areas of the trachea, right and left main bronchi, bronchus intermedius, right and left upper lobe, and left lower lobe bronchi. We performed analysis of covariances to assess whether airway size changed after a period on GAHT, using time between pre- and post-measurements as a covariate. Significance was set at p < 0.01. RESULTS: Pre-scans occurred an average of 2.2 ± 4.0 yrs before beginning GAHT. Transgender persons were on GAHT for an average of 3.7 ± 3.3 yrs (range: 1-14 yrs) at the time of their second scan. We found no significant differences in airway luminal cross-sectional areas for transgender persons on masculinizing or feminizing hormone therapy (p > 0.01; Table 1). CONCLUSION: Our findings suggest that the size of large conducting airways remains unchanged after a period of either masculinizing or feminizing GAHT. This may have implications for clinical practice and sports policies. Table 1. - Masculinizing Hormone Therapy n = 5 Feminizing Hormone Therapy n = 9 Airway Luminal Area Before GAHT OnGAHT p-value Before GAHT On GAHT p-value Trachea (mm2) 228 ± 48 253 ± 29 0.728 318 ± 45 339 ± 43 0.325 Right Main Bronchus (mm2) 146 ± 15 161 ± 21 0.330 214 ± 40 224 ± 32 0.515 Left Main Bronchus (mm2) 97 ± 15 108 ± 18 0.078 158 ± 24 167 ± 23 0.611 Bronchus Intermedius (mm2) 85 ± 3 90 ± 15 0.046 128 ± 17 134 ± 17 0.378 Right upper lobe bronchus (mm2) 63 ± 11 69 ± 15 0.912 74 ± 14 81 ± 16 0.553 Left upper lobe bronchus (mm2) 59 ± 11 57 ± 12 0.243 104 ± 17 103 ± 16 0.990 Left lower lobe bronchi (mm2) 42 ± 12 48 ± 16 0.019 60 ± 16 73 ± 15 0.160 Data is presented mean ± SD.