Obstructive sleep apnoea, cigarette smoking and serum testosterone levels in a male sleep clinic cohort.

This study evaluated the impact of obstructive sleep apnoea (OSA) and smoking on total serum testosterone levels in 96 men (mean age 43.3 years; range 25 - 60 years) attending a sleep clinic. Fifty-five men (57.3%) had OSA, defined as an apnoea-hypopnoea index of > or = 15 events/h, recorded during overnight polysomnography, and 42 (43.8%) were current smokers. Mean serum total testosterone levels were significantly lower in OSA subjects (3.4 ng/ml) than in non-OSA subjects (3.9 ng/ml), whereas no significant difference was observed between current smokers and nonsmokers. In a multiple linear regression analysis, serum testosterone was negatively correlated with body mass index and the apnoea-hypopnoea index, but not with age and pack-years of smoking. Our results support previous observations regarding testosterone levels in men with OSA, but, contrary to some earlier reports, there was no positive relationship between smoking and total testosterone in the present cohort.