title: Serum gamma-glutamyltransferase levels are inversely related to endothelial function in chronic kidney disease.
abstract: BACKGROUND
  Gamma-glutamyltransferase (GGT) is an enzyme responsible for the extracellular catabolism of the antioxidant glutathione and recently implicated in the pathogenesis of atherosclerosis. Endothelial dysfunction is a prodromal feature of atherogenesis. Since oxidative stress is highly present in uremia and causally linked to endothelial dysfunction, we hypothesized that GGT may be a factor implicated in this process.
  
  
  METHODS
  Serum GGT and C-reactive protein (CRP) levels, estimated glomerular filtration rate (eGFR), and 24-h proteinuria were measured in 214 nondiabetic stages 3-5 CKD patients. The endothelium-dependent vasodilatation (FMD) of the brachial artery was assessed by using high-resolution ultrasound. We investigated the relationship between FMD and circulating serum GGT.
  
  
  RESULTS
  Serum GGT levels were negatively associated with FMD (r = -0.41, p < 0.001) and eGFR (r = -0.34, p < 0.001) in univariate analysis. Multivariate regression analysis showed that the association between GGT and FMD persisted after adjustment for age, sex, smoking, renal function (eGFR), inflammation (CRP), proteinuria, and homeostatic model assessment index.
  
  
  CONCLUSIONS
  Circulating GGT levels significantly associate with endothelial dysfunction, an important early feature of the atherogenic process. GGT might be an early marker of oxidative or other cellular stress that it is possibly directly related to the pathogenesis of endothelial dysfunction.
authors.affiliation: Department of Nephrology, Gulhane School of Medicine, Ankara, Turkey.
authors.forename: Mahmut Ilker
authors.initials: MI
authors.lastname: Yilmaz
authors.forename: Faruk
authors.initials: F
authors.lastname: Turgut
authors.forename: Mehmet
authors.initials: M
authors.lastname: Kanbay
authors.forename: Mutlu
authors.initials: M
authors.lastname: Saglam
authors.forename: Alper
authors.initials: A
authors.lastname: Sonmez
authors.forename: Halil
authors.initials: H
authors.lastname: Yaman
authors.forename: Seref
authors.initials: S
authors.lastname: Demirbas
authors.forename: Hilmi Umut
authors.initials: HU
authors.lastname: Unal
authors.forename: Mahmut
authors.initials: M
authors.lastname: Gok
authors.forename: Murat
authors.initials: M
authors.lastname: Karaman
authors.forename: Seyit Ahmet
authors.initials: SA
authors.lastname: Ay
authors.forename: Erkan
authors.initials: E
authors.lastname: Demirkaya
authors.forename: Adrian
authors.initials: A
authors.lastname: Covic
authors.forename: Juan Jesus
authors.initials: JJ
authors.lastname: Carrero
mesh_terms: D000328:Adult; D000367:Age Factors; D050197:Atherosclerosis / Q000097:blood* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis / Q000378:metabolism*; D003430:Cross-Sectional Studies; D004730:Endothelium, Vascular / Q000201:enzymology* / Q000503:physiopathology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018384:Oxidative Stress / Q000502:physiology; D011379:Prognosis; D012016:Reference Values; D012044:Regression Analysis; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000453:epidemiology / Q000503:physiopathology*; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D005723:gamma-Glutamyltransferase / Q000097:blood*
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein; D005723:gamma-Glutamyltransferase