Sleep apnoe syndrome is associated with low serum testosterone levels and reversible by cpap- treatment

Sleep-apnea-syndrom (SAS) is characterized by repeated episodes of obstructive apnea and hypopnea during sleep and is often associated with erectile dysfunction and reduced libido. Cpap-therapy (cpap-Rx) is the treatment of choice in patients with SAS. Studies evaluating sex-hormone levels in patients with SAS were either evaluated only in small groups of patients or only in longer time intervals during cpap-Rx.

We therefore prospectively evaluated testosterone- (T), SHBG- and LH- levels in 45 male patients with SAS before, after 4 weeks and 6 months after initiating cpap-Rx (mean age 53±9 years; BMI 33.4±6.2; weight 103±20kg.

Results are given as mean±SD T was in the lower normal range (241.9±83 ng/dl; normal 212–742) with normal SHBG (28.9±11 nmol/l; normal 13–71)levels resulting in a low FAI(free androgen index) 0.32±0.15; (normal 0.3–1.8). Testosterone was positively correlated with minimal oxygen saturation (r=0.26, p<0.05) during nighttime. Cpap-Rx resulted in a significant decrease of AHI (Apnoe-hypopnoea-index) from 44/hour to 2/hour and an increase of REM-sleep episodes from 7% to 16% (p<0.001).

During cpap-therapy a significant rise of T- and FAI- levels was observed in patients with moderate and severe SAS after 4 weeks of cpap-Rx:(T:224.9 ng/dl±82 to 263.6±98; p<0.05 and FAI 0.29±0.12 to 0.38±0.13; p<0.05) without further improvement after 6 months. LH was not affected by cpap-Rx. Conclusion: Even young patients with SAS demonstrate T and FAI levels in the lower normal range. They are positively correlated with minimum oxygen saturation at nighttime. During 4 weeks of cpap-Rx a significant improvement of sleep architecture and a significant rise of T-concentrations and FAI could be observed.