title: Sleep oxygen desaturation and circulating leptin in obstructive sleep apnea-hypopnea syndrome.
abstract: BACKGROUND
  Obstructive sleep apnea-hypopnea syndrome (OSAHS) is characterized by repeated oxygen desaturation. Obesity and visceral fat accumulation (VFA) are risk factors for the development of OSAHS. Circulating leptin increases in accordance with body mass index (BMI), and under experimental conditions intermittent hypoxia stimulates leptin production.
  
  
  METHODS
  The primary objective of this study was to investigate whether hypoxemia during sleep influences the levels of circulating leptin and whether the location of body fat deposits, ie, the distribution of VFA and subcutaneous fat accumulation (SFA), affects circulating leptin levels in patients with OSAHA who are not obese. We assessed VFA and SFA by abdominal CT scan and measured circulating levels of leptin in 96 male patients with OSAHS and 52 male patients without OSAHS matched for BMI. To be matched for BMI in the two groups, patients whose BMIs were < 27 were selected for the OSAHS group.
  
  
  RESULTS
  In the whole study group, circulating leptin levels correlated with BMI (r = 0.30), VFA (r = 0.44), SFA (r = 0.28), apnea-hypopnea index (AHI) [r = 0.48], sleep mean arterial oxygen saturation (Sao(2)) [r = 0.59], and sleep lowest Sao(2) (r = 0.37). Multiple regression analysis showed that average Sao(2) (p < 0.01) and lowest Sao(2) (p = 0.03) were explanatory variables for serum leptin values, but AHI (p = 0.054), BMI (p = 0.33), VFA (p = 0.11), and SFA (p = 0.36) were not.
  
  
  CONCLUSIONS
  These results suggest that sleep hypoxemia may be the main determinant of circulating leptin levels, although the location of body fat deposits could contribute to the elevated circulating leptin levels in patients with OSAHS who are not obese.
authors.affiliation: Department of Respirology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuou-ku, Chiba 260-8670, Japan. tatsumi@faculty.chiba-u.jp
authors.forename: Koichiro
authors.initials: K
authors.lastname: Tatsumi
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Kasahara
authors.forename: Katsushi
authors.initials: K
authors.lastname: Kurosu
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Tanabe
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takiguchi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kuriyama
mesh_terms: D000005:Abdomen; D000273:Adipose Tissue / Q000473:pathology; D015992:Body Mass Index; D005541:Forced Expiratory Volume; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000473:pathology / Q000503:physiopathology; D040521:Subcutaneous Tissue; D014797:Vital Capacity
chemical_list: D020738:Leptin; D010100:Oxygen