title: Serum levels of gamma-glutamyl transferase are associated with markers of nocturnal hypoxemia in a general adult population.
abstract: BACKGROUND
  Serum gamma-glutamyl transferase (GGT) is a well-known marker of alcohol consumption and liver dysfunction. GGT is also associated with components of metabolic syndrome, cardiovascular risk factors and obstructive sleep apnea. In a population-based study, we investigated serum GGT levels in relation to markers of nocturnal hypoxemia, adjusting for potential confounders. In addition, we investigated the possible relationship between GGT concentrations and serum levels of tumour necrosis factor-alpha and interleukin-6.
  
  
  METHODS
  Demographic data, alcohol consumption, components of metabolic syndrome, serum liver enzymes, pro-inflammatory cytokines and nocturnal pulse oximetry were available for 220 individuals, randomly selected from a general adult population. Of these, overnight polysomnography was available for 70.
  
  
  RESULTS
  A smoothing regression model confirmed that serum GGT levels were associated positively and independently with male sex (P<0.001), ageing (P=0.001), heavy smoking (P=0.039), alcohol drinking (P<0.001), and body mass index (P=0.019). Serum GGT levels were associated negatively and independently with average arterial oxygen saturation during sleep (P=0.001).
  
  
  CONCLUSIONS
  Serum concentrations of GGT are associated with nocturnal arterial oxygen desaturations.
authors: Clinical Epidemiology Unit, Hospital Clinico Universitario de Santiago, Travesia da Choupana, s/n, 15706 Santiago de Compostela, Spain. francisco.gude.sampedro@sergas.es
authors: Francisco
authors: F
authors: Gude
authors: Jesús
authors: J
authors: Rey-Garcia
authors: Carmen
authors: C
authors: Fernandez-Merino
authors: Luis
authors: L
authors: Meijide
authors: Luis
authors: L
authors: García-Ortiz
authors: Carlos
authors: C
authors: Zamarron
authors: Arturo
authors: A
authors: Gonzalez-Quintela
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000428:Alcohol Drinking / Q000009:adverse effects; D001158:Arteries / Q000378:metabolism; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000150:complications / Q000453:epidemiology* / Q000209:etiology; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications; D008875:Middle Aged; D015999:Multivariate Analysis; D010100:Oxygen / Q000378:metabolism; D012044:Regression Analysis; D017678:Sex Distribution; D012907:Smoking / Q000009:adverse effects; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D055815:Young Adult; D005723:gamma-Glutamyltransferase / Q000097:blood*
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D005723:gamma-Glutamyltransferase; D010100:Oxygen