As mentioned above, previous studies have confirmed the efficacy of CPAP on endocrinal disordering and sexual dysfunction in OSA patients , , , however, whether serum testosterone can be normalized or not by CPAP in OSA patients is controversial. Firstly, Most of the included studies were before and after treatment study, only two RCTs, pre-and post-treatment data rather than treatment and control groups data were drawn. To evaluate the efficacy of continuous positive airway pressure (CPAP) on serum testosterone in men with obstructive sleep apnea (OSA). In addition to lower serum testosterone, patients with severe OSA also have higher levels of general fatigue, physical fatigue and mental fatigue, and reduced physical activity. A mouse study showed that loss of testosterone after gonadectomy results in a significant decrease in the amount of deep sleep, which can be treated by testosterone replacement therapy (TRT) . While the quantity and quality of sleep lead to reduced testosterone levels, there is also evidence to suggest the reverse. Therefore, clinicians are required to also screen men with obesity and low testosterone levels for OSAS. According to new research, the use of CPAP (Continuous Positive Airway Pressure) to treat severe Obstructive Sleep Apnea Syndrome (OSAS) can lead to a significant increase in testosterone levels. Further studies are thus needed reporting data on sleep duration, compliance to CPAP, months of use, OSA syndrome improvement, and BMI. In all, a limited number of studies specifically focusing on the effect of CPAP in hypogonadal patients was found, and this prevented any additional analysis (e.g., meta-regression) to explore the high heterogeneity of findings. In particular, the data in Li et al. (20) are not in line with the other studies, although no clear reason could be found in the study protocol. Some men experience mood swings, irritability, or emotional sensitivity during the initial weeks of therapy. Keeping skin clean and discussing topical treatments with your provider can help. Choosing the right TRT provider is one of the most important steps in minimizing risks. Each delivery method has a different absorption profile and side effect risk, which your provider should tailor to your lab results and health goals. The authors confirm that all data underlying the findings are fully available without restriction. Additional further subgroup analysis showed that the results did not change when subdivided by CPAP duration (3 months). Also testosterone is known to stimulate growth of prostate cancer in men diagnosed with the condition. Doctors also watch out for high red blood cell counts, which could increase the risk of clotting. Men get started on testosterone replacement and they feel better, but then it's hard to come off of it. General fatigue and malaise has so many other causes, and when most men get a blood test, the result is a normal testosterone level. In male patients with obesity, low levels of SHBG are consistently reported. Two hypotheses have been formulated in order to describe the interactions between OSA syndrome and serum testosterone. Twelve studies were found including adult patients with eugonadism or hypogonadism at baseline. Moreover, 49 patients were treated with sham-CPAP, 21 with mandibular advancement devices, and 12 with CPAP and simultaneous TRT; they were not included in the present review. A total of 388 male patients were included, of which 245 received oral and 143 nasal CPAP; information on the presence of diabetes was available for 44 patients (11%) (22, 29). The studies were published between 1989 and 2017 and had sample sizes ranging from 5 to 101 patients and a follow-up from 4 to 156 weeks. Only in Knapp et al. serum testosterone was measured by liquid chromatography mass spectrometry, which is considered as the most reliable method (22, 25).