title: Fatigue and serum testosterone in obstructive sleep apnea patients.
abstract: BACKGROUND
  Obstructive sleep apnea (OSA)-related fatigue is a common understudied symptom. Fatigue is associated with low serum testosterone level in non-OSA patients. No data are available about this association in OSA patients.
  
  
  OBJECTIVE
  To investigate in adult obese males affected by OSA, the relationship between fatigue and serum testosterone in order to identify predictors for OSA-related fatigue.
  
  
  METHODS
  Fifteen OSA patients and 15 control subjects participated. The parameters analyzed were serum testosterone morning concentration, polysomnography parameters, daytime sleepiness (Epworth Sleepiness Scale) and fatigue (Multidimensional Fatigue Inventory). Regression test was applied in order to show predictors of fatigue. Kruskal-Wallis test followed by post-hoc analysis was performed to test for differences between controls and OSA subgroups for testosterone, fatigue components and sleepiness.
  
  
  RESULTS
  Mean testosterone level was 3.55 ± 0.7 ng/mL in the OSA group, significantly lower than in controls (4.26 ± 1.1 ng/mL, P = 0.049). An inverse correlation was found between testosterone and fatigue scores (P < 0.01). Furthermore, a statistically significant difference was found between the control group and the severe OSA subgroup for general fatigue, physical fatigue, reduced activity and mental fatigue. However, no significant differences were found between controls and mild OSA. Among all variables, testosterone was the only independent significant predictor of physical fatigue (t = -2.56, P = 0.033, R = 0.978, R(2)  = 0.958) and reduced activity (t = -4.41, P = 0.002, R = 0.966, R(2)  = 0.934) in the OSA patients.
  
  
  CONCLUSIONS
  OSA-related fatigue was strongly associated with serum testosterone, together with OSA severity.
authors.affiliation: 'Grigore T. Popa' University of Medicine and Pharmacy, Iasi, Romania.|Clinic of Pulmonary Diseases, Iasi, Romania.
authors.forename: Raluca Mihaela
authors.initials: RM
authors.lastname: Bercea
authors.affiliation: 'Grigore T. Popa' University of Medicine and Pharmacy, Iasi, Romania.|Clinic of Pulmonary Diseases, Iasi, Romania.
authors.forename: Traian
authors.initials: T
authors.lastname: Mihaescu
authors.affiliation: 'Grigore T. Popa' University of Medicine and Pharmacy, Iasi, Romania.|Clinic of Pulmonary Diseases, Iasi, Romania.
authors.forename: Cristian
authors.initials: C
authors.lastname: Cojocaru
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.|Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway.
authors.forename: Bjørn
authors.initials: B
authors.lastname: Bjorvatn
mesh_terms: D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005221:Fatigue / Q000097:blood* / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000150:complications; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications*; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone
keywords: fatigue; obstructive sleep apnea; sleepiness; testosterone