The role of Obstructive Sleep Apnea and CPAP therapy in the functional hypogonadism of male patients with severe obesity

Background: Only a few studies have reported a correlation between severe Obstructive Sleep Apnea Syndrome (OSAS) and hypogonadism in patients with obesity, regardless of body mass index (BMI). However, longitudinal studies exploring the role of continuous positive airways pressure (CPAP) on gonadal function are scanty. Aim: To investigate in male subjects with severe/complicated obesity the role of OSAS in decreasing testosterone levels and evaluate the effects of CPAP on hormonal status. Methods: This cross-sectional study consecutively enrolled 204 male inpatients with complicated severe obesity, without known hypogonadism. Polysomnography (or overnight oximetry during CPAP) and blood tests for inflammation, metabolic and hormonal profiles were performed. "Decompensated OSAS" was defined as Apnea/Hypopnea Index (AHI) in newly diagnosed, or Oxygen Desaturation Index (ODI) in treated patients, above 30 events/hour. A multiple linear regression was implemented to identify the independent factors correlated with total testosterone (TT). Lastly, a longitudinal study of 14 newly diagnosed patients was performed to evaluate the effects of CPAP on TT after 3 months treatment. Results: 127/204 patients showed low TT (≤10.4 nmol/L). BMI, type 2 diabetes (T2DM), C-reactive Protein (CRP), and decompensated OSAS were independently associated with TT (p-value 0.039, p-value 0.006, p-value 0.003 and p-value 0.014 respectively). After 3 months of CPAP therapy, TT was higher (p-value 0.009) and ODI was associated with such improvement, independently of BMI (p-value 0.04). Conclusion: decompensated OSAS was found to correlate with low testosterone in males with severe obesity. Moreover, CPAP therapy was shown to improve TT independently of BMI changes.