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

Gamma-glutamyl transferase activity as a predictive marker for severity of obstructive sleep apnea syndrome and concomitant hypertension

BACKGROUND

Chronic intermittent hypia, inflammation and oxidative stress are involved in resultant obstructive sleep apnea syndrome (OSAS), which may affect numerous regulatory mechanisms that play a role in the regulation of blood pressure. Gamma-glutamyl transferase (GGT) is a novel marker in the prediction of cardiovascular risk.

OBJECTIVE

The objective of this study was to investigate the correlation of serum levels of GGT with hypertension and the degree of the upper airway obstruction in subjects with OSAS.

METHODS

A total of 270 subjects that met the inclusion criteria were enrolled in the study. The subjects were divided into four separate groups according to the apnea-hypopnea index (AHI) scores as the control group (AHI < 5), mild OSAS group (AHI 5-15), moderate OSAS group (AHI 16-30) and severe OSAS group (AHI >30). A further classification of the OSAS subjects was made in two groups based on the presence of hypertension.

RESULTS

The study included 43 control individuals and 59 subjects with mild, 54 subjects with moderate and 114 subjects with severe OSAS. The serum levels of GGT were found to be significantly correlated with OSAS severity (control group: 18 ± 3.3, mild OSAS: 23.6 ± 7.3, moderate OSAS: 26.4 ± 7.5 and severe OSAS: 39.8 ± 12). Serum levels of GGT were found to be significantly higher in OSAS subjects with concomitant hypertension than in the group without associated hypertension (P < .05). The results showed that the adjusted mean GGT under OSA without hypertension (M_adj  = 28.76, SE = 0.71) was significantly lower than in cases with OSA with hypertension (M_adj  = 42.79, SE = 1.19).

CONCLUSION

The present study indicated a strong correlation between high serum levels of GGT and concomitant hypertension in subjects with obstructive sleep apnea. This biomarker may be helpful in grading the severity of obstructive sleep apnea and correlated with hypertension in this population.

Serum levels of gamma-glutamyl transferase are associated with cardiovascular disease in obstructive sleep apnea syndrome

BACKGROUND AND OBJECTIVES

Obstructive sleep apnea syndrome (OSAS) significantly increases the risk of cardiovascular disease (CVD). Gamma-glutamyl transferase (GGT) is a new marker for predicting CVD. The aim of this study was to evaluate the relationship of serum GGT levels with cardiovascular event, severity of OSAS, and polysomnographic parameters in patients with OSAS.

DESIGN AND SETTINGS

This was a retrospective, cross-sectional study conducted between January 2011 and March 2013 (Gaziosmanpasa University, Faculty of Medicine, Tokat, Turkey).

METHODS

We performed a retrospective study. Patients were divided according to their apnea-hypopnea index (AHI) scores into OSAS negative (AHI < 5, Group 1), mild OSAS (AHI: 5-15, Group 2), moderate OSAS (AHI=15.30, Group 3), and severe OSAS (AHI > 30, Group 4) groups. The presence of heart failure, coronary artery disease, or arrhythmia was defined as CVD.

RESULTS

A total of 320 patients, with a mean age of 50.2 (10.8) years, were included in this study. There were 47, 68, 58, and 147 patients in Groups 1, 2, 3, and 4, respectively. Serum GGT levels were significantly different between groups (Group 1: 25.24 [14.95]; Group 2: 28.03 [11.92]; Group 3: 32.82 [18.18], and Group 4: 40.41 [31.90] mg/dL , P < .001). Besides, serum GGT levels were significantly correlated with AHI, oxygen desaturation index, and average and minimum O2 saturation values (P < .05). Serum GGT levels were significantly higher in patients with CVD compared with those without (P < .05). Multiple regression analysis demonstrated that independent predictors of CVD were serum GGT and low-density lipoprotein-cholesterol levels, age, and body mass index in patients with OSAS.

CONCLUSION

GGT level is an important predictor for CVD in patients with OSAS. The effectiveness of continuous positive airway pressure therapy on CVD and GGT levels should be investigated.

Determinants of serum concentrations of lipopolysaccharide-binding protein (LBP) in the adult population: the role of obesity

Background and Aim

Assessment of serum concentration of lipopolysaccharide (LPS)-binding protein (LBP) has been suggested as a useful biomarker to indicate activation of innate immune responses to microbial products. We investigated LBP concentrations and associations with demographics, lifestyle factors, and common metabolic abnormalities in adults. We also examined if LBP concentrations were associated with common polymorphisms in genes coding for LBP (rs2232618), CD14 (rs2569190), and TLR4 (rs4986790), the molecules responsible for the innate immune response to LPS, or serum levels of soluble CD14 (sCD14) and proinflammatory cytokines.

Methods

Serum LBP was measured with a commercial immunoassay in a random sample of the adult population (n = 420, 45% males, age 18–92 years) from a single municipality.

Results

Serum LBP concentrations increased with age (P<0.001) and were higher in individuals who were overweight or obese than in normal-weight individuals (P<0.001). Similarly, LBP concentrations were higher in individuals with metabolic syndrome than in individuals without it (P<0.001). Among metabolic syndrome components, LBP concentrations were independently associated with abdominal obesity (P = 0.002) and low concentrations of HDL-cholesterol (P<0.001). Serum LBP concentrations tended to be independently associated with smoking (P = 0.05), but not with alcohol consumption. Likewise, there was not significant association between LBP concentrations and gene polymorphisms. Concentrations of LBP significantly correlated with serum levels of proinflammatory cytokines (IL-6 and IL-8), sCD14, and with liver enzymes.

Conclusions

Serum LBP concentrations increased with age. Overweight, obesity, and having metabolic syndrome (particularly, low HDL cholesterol levels) were associated with higher LBP concentrations. These findings are consistent with microbial exposure playing a role in these inflammatory, metabolic abnormalities.

Obstructive sleep apnea and non-alcoholic Fatty liver disease: is the liver another target?

Obstructive sleep apnea (OSA) is recurrent obstruction of the upper airway during sleep leading to intermittent hypoxia (IH). OSA has been associated with all components of the metabolic syndrome as well as with non-alcoholic fatty liver disease (NAFLD). NAFLD is a common condition ranging in severity from uncomplicated hepatic steatosis to steatohepatitis (NASH), liver fibrosis, and cirrhosis. The gold standard for the diagnosis and staging of NAFLD is liver biopsy. Obesity and insulin resistance lead to liver steatosis, but the causes of the progression to NASH are not known. Emerging evidence suggests that OSA may play a role in the progression of hepatic steatosis and the development of NASH. Several cross-sectional studies showed that the severity of IH in patients with OSA predicted the severity of NAFLD on liver biopsy. However, neither prospective nor interventional studies with continuous positive airway pressure treatment have been performed. Studies in a mouse model showed that IH causes triglyceride accumulation in the liver and liver injury as well as hepatic inflammation. The mouse model provided insight in the pathogenesis of liver injury showing that (1) IH accelerates the progression of hepatic steatosis by inducing adipose tissue lipolysis and increasing free fatty acids (FFA) flux into the liver; (2) IH up-regulates lipid biosynthetic pathways in the liver; (3) IH induces oxidative stress in the liver; (4) IH up-regulates hypoxia inducible factor 1 alpha and possibly HIF-2 alpha, which may increase hepatic steatosis and induce liver inflammation and fibrosis. However, the role of FFA and different transcription factors in the pathogenesis of IH-induced NAFLD is yet to be established. Thus, multiple lines of evidence suggest that IH of OSA may contribute to the progression of NAFLD but definitive clinical studies and experiments in the mouse model have yet to be done.

Increased γ-glutamyl transferase levels predict early mortality in patients with acute pulmonary embolism

BACKGROUND

Increased γ-glutamyl transferase (GGT) level is associated with increased oxidative stress, all-cause mortality, the development of cardiovascular disease, and metabolic syndrome. However, its role in acute pulmonary embolism (PE) is unknown. In this study, we aimed to investigate the relationship between GGT and early mortality in patients with acute PE.

METHODS

A total of 127 consecutive patients with confirmed PE were evaluated. The optimal cutoff value of GGT to predict early mortality was measured as more than 55 IU/L with 94.4% sensitivity and 66.1% specificity. Patients with acute PE were categorized prospectively as having no increased (group I) or increased (group II) GGT based on a cutoff value.

RESULTS

Of these 127 patients, 18 patients (14.2%) died during follow-up. Among these 18 patients, 1 (1.4%) patient was in group I, and 17 (30.9%) patients were in group II (P < .001). γ-Glutamyl transferase level on admission, presence of shock, heart rate, oxygen saturation, right ventricular dilatation/hypokinesia, main pulmonary artery involvement, troponin I, alanine aminotransferase, alkaline phosphatase, and creatinine levels were found to have prognostic significance in univariate analysis. In the multivariate Cox proportional hazards model, GGT level on admission (hazard ratio [HR], 1.015; P = .017), presence of shock (HR, 15.124; P = .005), age (HR, 1.107; P = .010), and heart rate (HR, 1.101; P = .032) remained associated with an increased risk of acute PE-related early mortality after the adjustment of other potential confounders.

CONCLUSIONS

We have shown that a high GGT level is associated with worse hemodynamic parameters, and it seems that GGT helps risk stratification in patients with acute PE.