Serum levels of gamma-glutamyl transferase are associated with markers of nocturnal hypoxemia in a general adult population

BackgroundSerum 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-α and interleukin-6.MethodsDemographic 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.ResultsA 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).ConclusionsSerum concentrations of GGT are associated with nocturnal arterial oxygen desaturations.