title: Association between serum gamma-glutamyltransferase levels and coronary microvascular function in hypertensive patients.
abstract: OBJECTIVE
  Serum gamma-glutamyltransferase (GGT) level is an independent risk factor for cardiovascular (CV) disease, and there is a strong association between serum GGT levels and most CV risk factors, including hypertension; however, the role of serum GGT level as an independent risk factor for target organ damage in hypertension remains controversial. Accordingly, we aimed to determine whether serum GGT level is independently and specifically associated with coronary flow reserve (CFR) impairment in hypertensive patients.
  
  
  METHODS
  We examined 100 never-treated and newly diagnosed hypertensive individuals, and CFR was achieved in 97 (97%) of them. They were divided into two groups based on serum GGT levels.
  
  
  RESULTS
  Subjects with higher GGT had significantly impaired CFR as compared to those with lower GGT (2.10 +/- 0.36 versus 2.57 +/- 0.54, P < 0.0001). After adjusting for potential confounders, including age, sex, body mass index, blood pressure, lipids and glucose, we found that serum GGT levels were independently associated with CFR impairment (beta = -0.62, P < 0.0001). We also found that GGT level was a good predictor of low CFR at the receiver-operating characteristic curve. Area under the curve was 79% [95% confidence interval: 0.70-0.88], and GGT level was significantly predictive of low CFR (P < 0.0001).
  
  
  CONCLUSIONS
  These results support a role for serum GGT level as an independent marker of target organ damage in hypertensive subjects without concomitant risk factors.
authors.affiliation: Baskent University Faculty of Medicine, Department of Cardiology, Ankara, Turkey. caliskandr@yahoo.com
authors.forename: Mustafa
authors.initials: M
authors.lastname: Caliskan
authors.forename: Dogan
authors.initials: D
authors.lastname: Erdogan
authors.forename: Hakan
authors.initials: H
authors.lastname: Gullu
authors.forename: Ozgur
authors.initials: O
authors.lastname: Ciftci
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Yildirim
authors.forename: Semra
authors.initials: S
authors.lastname: Baycan
authors.forename: Aylin
authors.initials: A
authors.lastname: Yildirir
authors.forename: Haldun
authors.initials: H
authors.lastname: Muderrisoglu
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004452:Echocardiography; D005260:Female; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging / Q000201:enzymology* / Q000503:physiopathology*; D008297:Male; D008833:Microcirculation / Q000000981:diagnostic imaging / Q000503:physiopathology; D008875:Middle Aged; D005723:gamma-Glutamyltransferase / Q000097:blood*
chemical_list: D015415:Biomarkers; D005723:gamma-Glutamyltransferase