Serum gamma-glutamyltransferase within its normal concentration range is related to the presence of diabetes and cardiovascular risk factors

Exploring the Potential Performance of Fibroscan for Predicting and Evaluating Metabolic Syndrome using a Feature Selected Strategy of Machine Learning

Metabolic syndrome (MetS) includes several conditions that can increase an individual's predisposition to high-risk cardiovascular events, morbidity, and mortality. Non-alcoholic fatty liver disease (NAFLD) is a predominant cause of cirrhosis, which is a global indicator of liver transplantation and is considered the hepatic manifestation of MetS. FibroScan^® provides an accurate and non-invasive method for assessing liver steatosis and fibrosis in patients with NAFLD, via a controlled attenuation parameter (CAP) and liver stiffness measurement (LSM or E) scores and has been widely used in current clinical practice. Several machine learning (ML) models with a recursive feature elimination (RFE) algorithm were applied to evaluate the importance of the CAP score. Analysis by ANOVA revealed that five symptoms at different CAP and E score levels were significant. All eight ML models had accuracy scores > 0.9, while treebags and random forest had the best kappa values (0.6439 and 0.6533, respectively). The CAP score was the most important variable in the seven ML models. Machine learning models with RFE demonstrated that using the CAP score to identify patients with MetS may be feasible. Thus, a combination of CAP scores and other significant biomarkers could be used for early detection in predicting MetS.

Lean non-alcoholic fatty liver disease (Lean-NAFLD) and the development of metabolic syndrome: a retrospective study

Lean NAFLD is a special phenotypic closely correlated with metabolic syndrome (MS). The aim of this study is to investigate the MS development and the gender differences in lean NAFLD population. Participants were divided into 4 groups by BMI and NAFLD status. Descriptive analysis was performed to characterize baseline information. A total of 18,395 subjects were participated, and 1524 incident cases of MS were documented. Then, Kaplan–Meier curves were used to present the MS outcomes in different groups, and the NAFLD was found to be a riskier factor than obesity for MS. Subgroup analysis showed significantly higher MS incidence in female than male among lean NAFLD group, which is different from other groups. Although with higher prevalence in male, lean NAFLD seems to be a more harmful phenotype for females according to the TG, ALT and GGT levels. The logistic regressive analysis was performed to show the impact of NAFLD status and BMI changes on MS risk. Lean non-NAFLD subjects merely developed to NAFLD with no BMI status changes exhibited highest MS risk (ORs = 1.879, 95% CI 1.610–2.292) than that with both BMI increase and NAFLD development (ORs = 1.669, 95% CI 1.325–2.104). It also suggests the metabolic specificity of this population.

The association between elevated lipid profile and liver enzymes: a study on Bangladeshi adults

Dyslipidemia, a major contributor to cardiovascular diseases, is rapidly increasing in Asian countries including Bangladesh. In addition to the cardiovascular system, abnormal lipid levels are also known to cause complications in renal and hepatic systems. The data regarding dyslipidemia and its relationship with liver enzymes are scarce for the Bangladeshi population. Therefore, this study was conducted to estimate the prevalence of dyslipidemia and determine the relationship between lipid profile and liver enzymes in Bangladeshi adults. A total of 405 participants (318 males and 87 females) were enrolled in the study. Serum levels of TG, TC, LDL, HDL and liver enzymes including ALT, AST, GGT and ALP were analyzed using standard methods. Dyslipidemia and liver function tests abnormalities were defined according to the international standard guidelines. The association between elevated lipid profile markers and liver enzyme abnormalities was assessed by logistic regression analysis. Overall, the prevalence of elevated TG, TC, LDL and low HDL were 30.9%, 23.7%, 26.2% and 78.8%, respectively. On the other hand, the prevalence of elevated liver enzymes ALT, AST, GGT and ALP were 18.8%, 21.6%, 12.9% and 21.9%, respectively. Dyslipidemia and liver enzyme abnormalities were higher in diabetic and hypertensive participants than in the healthy participants. About 61% of participants with dyslipidemia had at least one or more elevated liver enzymes. In regression analysis, an independent association was observed between serum GGT and all lipid components. In conclusion, a high prevalence of dyslipidemia and liver enzyme abnormalities were observed among the study participants. Of the four liver enzymes, the serum levels of GGT showed an independent association with all lipid components. Moreover, this study indicates that subjects with dyslipidemia often have a higher chance of having liver diseases than subjects with no dyslipidemia. However, large-scale prospective studies are needed to understand the underlying mechanisms of lipid-induced hepatic dysfunction in the Bangladeshi population.

In utero exposure to parabens and early childhood BMI z-scores - Associations between placental ethyl paraben, longitudinal BMI trajectories and cord blood metabolic biomarkers

BACKGROUND

Parabens are used as antimicrobial preservatives in personal care products. Few studies have dealt with adverse health outcomes, transplacental transfer, and obesogenic effects of prenatal exposure to parabens. We examined the association between placental paraben levels and cord blood metabolic biomarkers, considering modulating effects of maternal pre-pregnancy BMI and underlying epigenetic mechanisms, and investigated longitudinal effects of in utero paraben exposure on early childhood trajectories of BMI z-scores.

METHODS

Placental concentrations of four parabens [methyl (MeP), ethyl (EtP), propyl (PrP), and butyl (BuP)] were measured by ultra-performance liquid chromatography/tandem mass spectrometry in 229 placentas of the ENVIRONAGE birth cohort. The association with cord blood metabolic biomarkers [glucose, insulin, γ-glutamyltransferase (GGT), high-density and low-density lipoprotein (HDL and LDL)] was analyzed in multiple regression models with two different sets of, a priori selected potential confounders, additionally stratified for different maternal BMI groups and assessed by causal mediation analysis. The association between placental paraben concentration and differential DNA methylation of CpGs annotated to GGT and longitudinal measurements of BMI z-scores were investigated with adjusted linear mixed models.

RESULTS

The geometric means of placental MeP, EtP, PrP, and BuP levels above the limit of detection (LOD) were 4.42, 1.32, 1.51, and 0.35 ng/g respectively, with only EtP showing sufficient (88%) measurements above LOD for further analyses. An interquartile ratio (IQR) increase in placental EtP was associated with an increase of 12.61 % (95% CI: 1.80 24.57) in the geometric mean of cord GGT activity, and with a decrease of -3.64 % (95% CI: -6.80 to -0.39) in the geometric mean of cord glucose. Placental EtP levels were significantly associated with hypermethylation of cg08612779 annotated to GGT7 after correcting for multiple testing (ß = 0.0017, p = 0.049). An interquartile ratio (IQR) increment in placental EtP was associated with a decrease in longitudinal BMI z-score of 0.27 points (95% CI: -0.46 to -0.088).

CONCLUSION

Prenatal EtP exposure may affect early childhood BMI. The association of placental EtP with cord blood GGT and glucose levels provides a starting point for further research on mechanisms of paraben-related metabolic processes in utero.

Assessment of the relationship between serum uric acid levels and liver enzymes activity in Bangladeshi adults

Serum uric acid (SUA) level has been suggested to be associated with cardiovascular disease, diabetes and metabolic syndrome. However, little is known about the relationship between SUA and liver enzymes activity in the general population. The present study aimed to assess the relationship between SUA and serum liver enzymes in an adult population in Bangladesh. In this cross-sectional study, a total of 410 blood samples were collected from apparently healthy adults aged > 18 years. SUA, liver enzymes, lipid profile and other biochemical markers were measured in the collected samples by using standard methods. Multinomial logistic regression model was used to assess the relationship between SUA and elevated levels of liver enzymes among the participants. Overall, the prevalence of hyperuricemia was 30.1% with 32.2% in male and 18.6% in female participants. About 33% of the participants had at least one or more elevated levels of liver enzymes. The mean level of SUA was significantly higher in males (389.3 ± 96.9 µmol/L) than in the female (290.4 ± 89.8 µmol/L) subjects (p < 0.001). There was a significant difference in the mean levels of serum ALT and GGT between the male (34.5 ± 16.0 U/L and 26.7 ± 19.5 U/L, respectively) and female (25.0 ± 13.0 U/L and 19.5 ± 13.2 U/L, respectively) participants (p < 0.001 and p < 0.01, respectively). An increasing trend was observed in the mean levels of serum ALT and GGT across the SUA quartile groups (p < 0.001 and p < 0.01, respectively). SUA showed a positive and significant correlation with serum ALT (p < 0.001) and GGT (p < 0.01). In further statistical analysis after adjustment for potential confounders, SUA showed an independent and significant association with serum ALT and GGT in all regression models. In conclusion, SUA was strongly associated with serum levels of ALT and GGT after adjustment for potential confounders. More prospective studies are needed to clarify the complex relationship between SUA and liver enzymes in the general population.

Prevalence of elevated liver enzymes and its association with type 2 diabetes: A cross-sectional study in Bangladeshi adults

BACKGROUND

Type 2 diabetes (T2D) is a major public health concern affecting millions of people worldwide. The relationship between liver enzymes and T2D has been reported in limited studies; however, there is still a lack of evidence for the Bangladeshi population. This study aimed to evaluate the prevalence of elevated liver enzymes and examine its association with the prevalence of T2D in Bangladeshi adults.

METHODS

A total of 270 individuals (110 diabetic and 160 nondiabetic) were enrolled in the study. Alanine and aspartate aminotransferase (ALT, AST), alkaline phosphatase (ALP) and γ-glutamyltransferase (GGT) activities were measured in blood serum collected from them. T2D was defined as fasting blood glucose (FBG) ≥126 mg/dL or self-reported recent use of insulin or antidiabetic medications. Association between liver enzymes and T2D was evaluated by multinomial logistic regression analysis.

RESULTS

Overall, 61.2% of participants in T2D and 37.1% of participants in the nondiabetes group had at least one or more elevated liver enzymes. The mean concentrations of serum ALT, AST, ALP and GGT were significantly higher in the T2D group compared to the nondiabetes group. The prevalence of elevated liver enzymes was significantly higher in the diabetes group compared to the nondiabetes group (P < .01). In regression analysis, serum GGT activity showed an independent association with the prevalence of T2D.

CONCLUSIONS

A high prevalence of elevated liver enzymes was observed in subjects having diabetes. Increased serum GGT activity was independently associated with the prevalence of T2D among Bangladeshi adults. More studies of this nature should be carried out in developing countries to get proper insights into the involvement of liver enzymes in T2D.

The mercapturic acid pathway

The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Mercapturic acids (N-acetyl-l-cysteine S-conjugates) are formed by the sequential action of the glutathione transferases, γ-glutamyltransferases, dipeptidases, and cysteine S-conjugate N-acetyltransferase to yield glutathione S-conjugates, l-cysteinylglycine S-conjugates, l-cysteine S-conjugates, and mercapturic acids; these metabolites constitute a "mercapturomic" profile. Aminoacylases catalyze the hydrolysis of mercapturic acids to form cysteine S-conjugates. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals. Although mercapturic acid formation and elimination is a detoxication reaction, l-cysteine S-conjugates may undergo bioactivation by cysteine S-conjugate β-lyase. Moreover, some l-cysteine S-conjugates, particularly l-cysteinyl-leukotrienes, exert significant pathophysiological effects. Finally, some enzymes of the mercapturic acid pathway are described as the so-called "moonlighting proteins," catalytic proteins that exert multiple biochemical or biophysical functions apart from catalysis.

Association between Serum Gamma-Glutamyltransferase and Prevalence of Metabolic Syndrome Using Data from the Korean Genome and Epidemiology Study

BACKGROUND

The aim of this study was to determine whether there is a positive correlation between gamma-glutamyltransferase (GGT) levels and the prevalence of metabolic syndrome and whether GGT can be used as an easily checkable metabolic index using data from the large-scale Korean Genome and Epidemiology Study (KoGES).

METHODS

We obtained data of 211,725 participants of the KoGES. The collected data included age, sex, height, weight, waist circumference, and various biochemical characteristics, including serum GGT levels. The data of study participants who ingested more than 40 g/day of alcohol and who were diagnosed with metabolic syndrome at baseline was excluded. We analyzed the prevalence of metabolic syndrome according to GGT quartiles in both genders.

RESULTS

The GGT level was significantly higher in subjects with metabolic syndrome compared to normal subjects (37.92±48.20 mg/dL vs. 25.62±33.56 mg/dL). The prevalence of metabolic syndrome showed a stepwise increase with GGT quartiles in both male and female subjects. Compared to the lowest GGT quartile, the odds ratio was 1.534 (95% confidence interval [CI], 1.432 to 1.643), 1.939 (95% CI, 1.811 to 2.076), and 2.754 (95% CI, 2.572 to 2.948) in men and 1.155 (95% CI, 1.094 to 1.218), 1.528 (95% CI, 1.451 to 1.609), and 2.022 (95% CI, 1.921 to 2.218) in women with increasing GGT quartile. The cutoff value of GGT predicting risk of metabolic syndrome was 27 IU/L in men and 17 IU/L in women.

CONCLUSION

We suggested that GGT could be an easily checkable marker for the prediction of metabolic syndrome.

Risk factors associated with nonalcohol fatty liver disease and fibrosis among patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is closely related to hepatic steatosis and fibrosis. The aim of this study was to analyze the occurrence of hepatic steatosis and fibrosis in patients with T2DM and to explore the risk factors.A total of 629 patients with T2DM were enrolled. Liver stiffness value (LSV) and controlled attenuation parameters (CAP) were measured using Fibroscan. Liver fibrosis was diagnosed when LSV was greater than 7.4 kPa, and advanced liver fibrosis was diagnosed when LSV was greater than 10.6 kPa. Hepatic steatosis diagnosis was made when CAP value was greater than 238 dB/m. Demographic information, physical examination data, and laboratory tests results were collected. The 629 patients were classified into 2 groups by the liver fibrosis and liver steatosis, and then the difference was analyzed.Among patients enrolled, 231 patients were diagnosed as liver fibrosis. The age of the patients in the fibrosis group was significantly greater than that in the non-fibrosis group, and similar trends were observed in the waist-hip ratio (WHR), systolic blood pressure, and diastolic blood pressure. The proportion of smoking and alcoholic consumption was significantly lower in patients with non-fibrosis group. A total of 426 patients were diagnosed with liver steatosis. Body mass index (BMI), WHR, systolic blood pressure, and diastolic blood pressure in patients with steatosis were significantly higher than those in non-steatosis group. We observed that the LSV (P = .042) and CAP value (P < .001) are positively correlated with metabolic syndrome components in T2DM patients. Older age (OR = 1.099, P = .001), high BMI (OR = 1.088, P = .003), low platelet level (OR = 0.996, P = .014), and smoking (OR = 1.653, P = .013) were independent risk factors of liver fibrosis among T2DM patients. High BMI (OR = 1.369, P < .001), high diastolic blood pressure (OR = 1.048, P < .001), and high gamma glutamyl transpeptidase (OR = 1.018, P = .009) were independent risk factors for liver steatosis among T2DM patients.This study suggested risk factors screening of liver fibrosis and steatosis. Timely intervention should be taken into consideration among high risk patients to prevent progress liver diseases.

Predictive Value of Serum Gamma-glutamyltranspeptidase for Future Cardiometabolic Dysregulation in Adolescents- a 10-year longitudinal study

Serum gamma-glutamyltransferase (γ-GT) is implicated in the pathogenesis of atherosclerosis and metabolic syndrome (MetS) in adults. The relationships between γ-GT and cardiometabolic dysregulation remains unclear in adolescents. We enrolled 7,072 Taiwanese adolescents and followed them for a median of 6.8 years. The optimal cut-off values (CoVs) of baseline γ-GT to predict future MetS, hypertension (HTN), and type 2 diabetes (T2DM) were determined by receiving operating characteristic (ROC) curve. Using these CoVs, the participants were divided into normal- and high-level groups. Cox proportional hazard analysis was used to calculate hazard ratios (HRs) for the subjects with a high level of γ-GT for the risk of future cardiometabolic dysregulation. Serum γ-GT was significantly higher in the subjects with MetS than in those without MetS at baseline (p < 0.001). The optimal CoVs of γ-GT were 12 U/L for boys and 11 U/L for girls. In multivariate Cox regression analysis, a higher serum γ-GT level increased the risk of future MetS (HRs 1.98 and 2.85 for boys and girls, respectively, both p < 0.001), but not new onset HTN and T2DM. In conclusion, serum γ-GT levels not only demonstrated an excellent correlation with the presence of MetS and also in predicting future MetS in adolescents.

Elevated serum gamma-glutamyltransferase is associated with an increased risk of oesophageal carcinoma in a cohort of 8,388,256 Korean subjects

Gamma-glutamyltransferase (GGT) is a marker for hepatic injury and alcohol consumption. However, the association of GGT with the risk of oesophageal carcinoma (OC) has not been fully recognized to date. Therefore, this study aimed to determine the association between elevated GGT and OC, by also considering the body mass index (BMI) of the subjects. Clinical data from 8,388,256 Korean individuals, who were aged 40 years and over and who received healthcare check-ups arranged by the national insurance program in 2007 and 2008, were analysed. Newly diagnosed OC was identified using claims data during a median follow-up duration of 8.72 years. During the study period, 6,863 individuals (0.08%) developed OC. We found that there was an increased risk of OC in subjects with serum GGT values >18 IU/L. Furthermore, a BMI <18.5 kg/m² (underweight) was associated with increased OC risk, while a BMI ≥23.0 kg/m² was associated with a reduced OC risk. Individuals who were both underweight and in the highest GGT quartile (≥40 IU/L) had a far greater risk of OC compared to other individuals (hazard ratio: 3.65, 95% confidence interval: 3.10–4.30). In conclusion, increased serum GGT was associated with an increased risk of developing OC in the general Korean population, regardless of age, sex, smoker status, or alcohol consumption.

Gamma-glutamyltransferase and risk of cardiovascular mortality: A dose-response meta-analysis of prospective cohort studies

BACKGROUND

Serum gamma-glutamyltransferase (GGT) elevation likely contributes to cardiovascular (CV) mortality, however it has remained unknown whether a dose-response relationship exists between serum GGT and CV mortality.

METHODS

We searched the PubMed, EMBASE, and Cochrane library databases for prospective cohort studies published up to October 2, 2016. Summary hazard ratios (HRs) with their corresponding 95% confidence intervals (CIs) were calculated using a fixed effects model.

FINDINGS

Nine prospective studies, including 527,589 participants and more than 7,011 cases, were included in this meta-analysis. For the moderate, high, and highest levels of GGT, the pooled HRs of CV mortality were 1.11 (95% CI = 1.04-1.19), 1.29 (95% CI = 1.21-1.38) and 1.59 (95% CI = 1.47-1.72), respectively (all p < 0.05 as compared to the lowest levels of GGT). Additionally, the HR per incremental increase of GGT by 10 U/L was 1.10 (95% CI = 1.08-1.11). Evidence of a positive relationship with nonlinear trend for GGT elevation with CV mortality in females was found (P = 0.04 for nonlinearity). However, a linear model was better fit to illustrate the GGT-CV mortality among males (P = 0.304 for nonlinearity).

CONCLUSIONS

These findings indicate that serum GGT activity within the reference interval is positively associated with increased risk of CV mortality in a dose-response manner.

Association of adiposity, measures of metabolic dysregulation, and elevated alanine aminotransferase in subjects with normal body mass index

Background: Differences in body fat (BF) distribution in patients with normal body mass index (BMI) with elevated alanine aminotransferase (ALT) remains poorly described.

Objective: To determine the relationship between total BF, waist circumference (WC), insulin resistance (IR), and cardiometabolic risk profile in subjects with elevated ALT and normal BMI.

Methods: We analyzed cross-sectional data from 4,914 US participants in the third National Health and Nutrition Examination Survey database, who were ≥20 years of age, had normal BMI, and had body composition assessed by bioimpedance.

Results: Mean ± SD age was 41.4 ± 0.3 years, and 58% participants were women. BF was 20 ± 0.1% in men and 29.9 ± 0.1% in women. As total BF increased by tertiles, there was a tendency towards a higher prevalence of nonalcoholic fatty liver disease in men (6.1%, 6.5%, 9.5%, P = 0.13), but not in women (8.7%, 8.2%, 10.7%, P = 0.71). As WC increased by tertiles, there was a higher prevalence of elevated ALT in men (2.6%, 8.6%, 6.6%, P < 0.0001), but not in women. As ALT increased, men had significantly higher levels of nonhigh density lipoprotein cholesterol (HDL-C), increased apolipoprotein B, increased IR, and lower levels of C-reactive protein, whereas, women had higher levels of non-HDL-C and increased IR.

Conclusion: In subjects with normal BMI, increased WC is associated with a higher prevalence of elevated ALT in men, but not in women. Higher levels of ALT correlated with a poor cardiometabolic risk profile.

Association between gamma-glutamyltransferase and albuminuria in nondiabetic adults with normal renal function

BACKGROUND

Serum gamma-glutamyltransferase (GGT) has been associated with albuminuria in diabetes patients, but it has not been investigated in the general population. We aimed to investigate the association between serum GGT and albuminuria in the nondiabetic Korean population with normal kidney function.

METHODS

Study participants (3948; 1549 men and 2399 women) with an estimated glomerular filtration rate ≥60 mL/min/1.73 m² were analyzed from the fifth Korean National Health and Nutrition Examination Survey (2011). Albuminuria was defined as an albumin-creatinine ratio >30 mg/g. Serum GGT was analyzed by dividing into quartiles. Multiple logistic models were used to analyze the associations between GGT and albuminuria.

RESULTS

The prevalence of albuminuria was 5.1% and increased linearly according to increasing GGT quartiles (P for trend = 0.005). A linear regression analysis revealed that GGT was positively related with albuminuria (P = 0.008). After adjusting for confounding factors, the odds ratio for albuminuria was 1.80 (95% CI 1.079-3.010, P for trend = 0.029) for the highest quartile group compared with those observed in the lowest quartile of GGT. In addition, this independent relationship did not change when the cut-off value of GGT (30 IU/L) was applied to this analysis. Compared with GGT value ≤30 IU/L, the adjusted odds ratio of albuminuria in participants with GGT >30 IU/L was 1.96 (95% CI 1.319-2.906, P < 0.001).

CONCLUSION

Higher serum GGT levels within the reference range were significantly associated with albuminuria in nondiabetic Koreans with preserved kidney function, independently of traditional cardio-renal risk factors.

Risks of borderline liver enzyme abnormalities to the incidence of impaired fasting glucose and diabetes mellitus: a 7 year follow up study of workers

Background

The aim of this study was to identify the relationships between borderline serum liver enzyme abnormalities and the incidence of impaired fasting glucose (IFG) and diabetes mellitus (DM) during a 7-year follow-up of workers, and to evaluate the quantitative level of risks.

Methods

A total of 749 workers in an electronics manufacturing company were divided into the normal fasting blood glucose (n = 633), IFG (n = 98), and DM (n = 18) groups, according to the results of their health checkup in 2006. Among 633 workers in the normal group, excluding 55 workers who were impossible to follow, incidence rate and relative risks of 578 workers to the IFG or DM in 2013 according to the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyltransferase (γ-GTP) were investigated. The liver enzyme levels were categorized as A (normal), B (borderline elevation), and R (definite elevation) following the standard of the National Health Insurance Service of Korea.

Results

The incidence rate of IFG or DM based on ALT level was 9.7 % for the A, 30.0 % for B, and 15.4 % for R. According to γ-GTP, the incidence rate was 9.8 % for A, 34.5 % for B, and 25.0 % for R. The relative risk(RR) to the incidence of IFG or DM depending on the level of ALT were 3.09 in B and 1.59 in R compared to A. According to γ-GTP, RR was 3.52 in B and 2.55 in R compared to A. AST level was not related to the incidence of IFG or DM. A multiple logistic regression analysis with the incidence of IFG or DM as a dependent variable resulted in an odds ratio of 2.664(1.214–5.849) for B level ALT, 3.685(1.405–9.667) for B level of γ-GTP even after adjustment for other variables such as age, sex, body mass index, AUDIT score, systolic blood pressure, and triglyceride.

Conclusions

Even borderline elevations of ALT and γ-GTP, but not AST, increased the incidence and risk of IFG or DM after 7 years. Borderline elevation of ALT and γ-GTP was identified as an independent risk factor of IFG or DM.

γ-Glutamyltransferase and cancer risk: The Korean cancer prevention study

Elevated serum γ-glutamyltransferase (GGT) is a marker of hepatic injury and is associated with risk of chronic disease. However, the value of GGT as a biomarker for cancer risk remains unclear. Therefore, we evaluated the association of serum GGT with cancer incidence among more than 1.6 million Koreans. We included 1,662,087 Koreans (1,108,121 men and 553,966 women aged 20-95 years) who received health insurance from the National Health Insurance Service and had a biennial medical evaluation between 1995 and 1998. Follow-up was through December 2012. Using Cox proportional hazards models, we adjusted for age, smoking status, alcohol consumption, exercise and body mass index after exclusion of early cases (cancer diagnosis or death within 5 years of starting follow-up) and estimated hazard ratios (HRs) of overall and organ-specific cancer incidence by GGT quintiles. During the 17-year follow-up, 129,087 new cancer cases occurred among the participants. Across levels of GGT, there was a positive gradient of HR and the highest quintile of GGT (≥ 60 IU/L) had the highest HR for all cancers in both men and women. By cancer site, the association was strongest for liver cancer, comparing the highest and lowest strata in men [HR, 6.67; 95% confidence interval (95%CI), 5.88-7.57] and in women (HR, 7.57; 95%CI, 6.41-8.94). Significant associations were also observed for cancers of the esophagus, larynx, stomach, colorectal, bile duct and lung in men and of the bile duct in women. Increased serum GGT level is independently associated with risk of cancer.

What does serum γ-glutamyltransferase tell us as a cardiometabolic risk marker?

γ-glutamyltransferase plays a key role in the synthesis and metabolism of extracellular glutathione, a major antioxidant in several defence mechanisms in the body. γ-glutamyltransferase is affected by environmental and genetic factors, and is raised when there is depletion of glutathione. Hence, it is a marker of oxidative stress. There is robust evidence that γ-glutamyltransferase even when values are within the reference interval is associated with increased cardiovascular and all-cause mortality in both sexes, in normal subjects and subjects with coronary artery disease, in the middle-aged and the elderly after adjusting for confounding factors. γ-glutamyltransferase even within the reference interval is associated with future presentation of type 2 diabetes, and the longitudinal increase in γ-glutamyltransferase activity is associated with increased risk of type 2 diabetes and cardiovascular mortality. γ-glutamyltransferase is associated with cardiovascular risk factors and metabolic syndrome. It has a prognostic value after a previous acute myocardial infarction and may be an indicator of adverse outcome in acute coronary syndromes and other chronic cardiac disorders. There is limited data about γ-glutamyltransferase and any association with peripheral arterial disease and also whether knowing γ-glutamyltransferase activity improves cardiovascular risk prediction beyond conventional risk factors. γ-glutamyltransferase is present in atherosclerotic lesions in the coronary and carotid arteries, and has a prooxidant role leading to the production of reactive oxygen species and atherosclerosis. Current reference intervals for γ-glutamyltransferase are inappropriate and need to be addressed. Some laboratories still use non- International Federation of Clinical Chemistry methods for estimation of γ-glutamyltransferase which are associated with lower results. Such laboratories should review their method and consider changing to the International Federation of Clinical Chemistry method.

Prognostic relevance of pretherapeutic gamma-glutamyltransferase in patients with primary metastatic breast cancer

Background

Gamma-glutamyltransferase (GGT) is a known marker for apoptotic balance and cell detoxification. Recently, an association of baseline GGT levels and breast cancer incidence, tumor progression and chemotherapy resistance was shown. The purpose of this study was to evaluate the association of pre-therapeutic GGT levels, clinical-pathological parameters and survival in patients with primary metastatic breast cancer (PMBC).

Methods

In this multicenter analysis, pre-therapeutic GGT levels and clinical-pathological parameters of 114 patients diagnosed with PMBC between 1996 and 2012 were evaluated. The association between GGT levels and clinical-pathological parameters were analysed. Patients were stratified into four GGT risk-groups (GGT < 18.00 U/L: normal low, 18.00 to 35.99 U/L: normal high, 36.00 to 71.99 U/L: elevated and ≥ 72.00 U/L: highly elevated) and survival analyses were performed.

Findings

Patients in the high risk GGT group had a poorer overall survival, when compared to the low risk group with five-year overall survival rates of 39.5% and 53.7% (p = 0.04), respectively. Patients with larger breast tumors had a trend towards higher GGT levels (p = 0.053). Pre-therapeutic GGT levels were not associated with indicators of aggressive tumor biology such as HER2-status, triple negative histology, or poorly differentiated cancers.

Conclusion

Pre-therapeutic GGT serum level might serve as a novel prognostic factor for overall-survival in patients with PMBC.

Glycated Hemoglobin is a Better Predictor than Fasting Glucose for Cardiometabolic Risk in Non-diabetic Korean Women

This study aimed to investigate if glycated hemoglobin (Hgb_A1C) as compared to fasting blood glucose is better for reflecting cardiometabolic risk in non-diabetic Korean women. Fasting glucose, Hgb_A1C and lipid profiles were measured in non-diabetic women without disease (n = 91). The relationships of fasting glucose or Hgb_A1C with anthropometric parameters, lipid profiles, and liver and kidney functions were analyzed. Both fasting glucose and Hgb_A1C were negatively correlated with HDL-cholesterol (r = -0.287, p = 0.006; r = -0.261, p = 0.012), and positively correlated with age (r = 0.202, p = 0.008; r = 0.221, p = 0.035), waist circumference (r = 0.296, p = 0.005; r = 0.304, p = 0.004), diastolic blood pressure (DBP) (r = 0.206, p = 0.050; r = 0.225, p = 0.032), aspartate transaminase (AST) (r = 0.237, p = 0.024; r = 0.368, p < 0.0001), alanine transaminase (ALT) (r = 0.296, p = 0.004; r = 0.356, p = 0.001), lipid profiles including triglyceride (r = 0.372, p < 0.001; r = 0.208, p = 0.008), LDL-cholesterol (r = 0.315, p = 0.002; r = 0.373, p < 0.0001) and total cholesterol (r = 0.310, p = 0.003; r = 0.284, p = 0.006). When adjusted for age and body mass index, significant relationships of DBP (r = 0.190, p = 0.049), AST (r = 0.262, p = 0.018), ALT (r = 0.277, p = 0.012), and HDL-cholesterol (r = -0.202, p = 0.049) with Hgb_A1C were still retained, but those with fasting glucose disappeared. In addition, the adjusted relationships of LDL-cholesterol and total cholesterol with Hgb_A1C were much greater than those with fasting glucose. These results suggest that glycated hemoglobin may be a better predictor than fasting glucose for cardiometabolic risk in non-diabetic Korean women.

Liver function parameters in hip fracture patients: relations to age, adipokines, comorbidities and outcomes

AIM

To asses liver markers in older patients with hip fracture (HF) in relation to age, comorbidities, metabolic characteristics and short-term outcomes.

METHODS

In 294 patients with HF (mean age 82.0±7.9 years, 72.1% women) serum alanine aminotransferase (ALT), gammaglutamyltransferase (GGT), alkaline phosphatase (ALP), albumin, bilirubin, 25(OH)vitaminD, PTH, calcium, phosphate, magnesium, adiponectin, leptin, resistin, thyroid function and cardiac troponin I were measured.

RESULTS

Elevated ALT, GGT, ALP or bilirubin levels on admission were observed in 1.7%-9.9% of patients. With age GGT, ALT and leptin decrease, while PTH and adiponectin concentrations increase. Higher GGT (>30 U/L, median level) was associated with coronary artery disease (CAD), diabetes mellitus (DM), and alcohol overuse; lower ALT (≤20 U/L, median level) with dementia; total bilirubin>20 μmol/L with CAD and alcohol overuse; and albumin>33 g/L with CAD. Multivariate adjusted regression analyses revealed ALT, ALP, adiponectin, alcohol overuse and DM as independent and significant determinants of GGT (as continuous or categorical variable); GGT for each other liver marker; and PTH for adiponectin. The risk of prolonged hospital stay (>20 days) was about two times higher in patients with GGT>30 U/L or adiponectin>17.14 ng/L (median level) and 4.7 times higher if both conditions coexisted. The risk of in-hospital death was 3 times higher if albumin was <33 g/L.

CONCLUSIONS

In older HF patients liver markers even within the normal range are associated with age-related disorders and outcomes. Adiponectin (but not 25(OH)vitaminD, PTH, leptin or resistin) is an independent contributor to higher GGT. Serum GGT and albumin predict prolonged hospital stay and in-hospital death, respectively. A unifying hypothesis of the findings presented.

Gamma-glutamyl transferase levels in patients with acute ischemic stroke

Objective. The aim of this study was to investigate the relationship between gamma-glutamyl transferase (GGT) levels, cerebrovascular risk factors, and distribution of cerebral infarct areas in patients with acute ischemic stroke (AIS). Patients and Methods. Sixty patients with AIS and 44 controls who had not cerebrovascular disease were included in the study. The patients were divided into four groups according to the location of the infarct area and evaluated as for GGT levels and the presence of diabetes mellitus (DM), hypertension (HT), and hyperlipidemia (HL). Results. The frequency of DM, HT, and HL and gender distributions were similar. The mean GGT levels were significantly higher in patients with AIS and those with relatively larger areas of infarction (P < 0.05). Increased mean GGT levels were found in the subgroup with hypertension, higher LDL-cholesterol, and triglyceride levels among cases with AIS (P < 0.05). Conclusion. Higher GGT levels in AIS patients reinforce the relationship of GGT with inflammation and oxidative stress. The observation of higher GGT levels in patients with relatively larger areas of infarction is indicative of a positive correlation between increases in infarct areas and elevated GGT levels.

Increasing risk of diabetes mellitus according to liver function alterations in electronic workers

Aims/Introduction

We sought to determine the association between change in fasting plasma glucose (FPG) and levels of liver enzymes, such as aspartate transaminase, alanine transaminase and gamma-glutamyltransferase, from health examinations.

Materials and Methods

A total of 9,393 health screen examinees with no evidence of viral hepatitis, liver diseases, abnormal liver function and diabetes in their past disease history were enrolled in the present study. All the participants underwent three health examinations. Group 1 and 4 were stationary groups of those with normal liver enzyme levels in the first and second health examinations (G1), and abnormal liver enzyme levels in the first and second health check-up (G4). Groups 2 and 3 were altered groups of those with abnormal liver enzyme levels in the first health examination, which became normal in the second health examination (G2), and from a normal liver enzymes level to an abnormal liver enzymes level (G3).

Results

FPG levels were elevated in male participants (P < 0.01), and were related to old age (P < 0.01), drinking (P < 0.01), smoking (P < 0.01) and so on. There was a strong relationship between FPG levels in the last health examination and altered liver function enzyme levels from the first health examination to the second check-up. In other words, group 4 had the highest level of FPG compared with the other groups (G1 < G2 < G3).

Conclusions

An association was observed between FPG levels and abnormal liver function in manufacturing workers. Abnormal liver function can be closely associated with the development of diabetes.

Plasma gamma-glutamyltransferase is strongly determined by acylation stimulating protein levels independent of insulin resistance in patients with acute coronary syndrome

Background. Steatosis is a manifestation of the metabolic syndrome often associated with release of liver enzymes and inflammatory adipocytokines linked to cardiovascular risk. Gamma-glutamyltransferase (GGT) is one sensitive liver marker recently identified as an independent cardiovascular risk factor. Mechanisms involved in enhanced hepatic lipogenesis causing steatosis are not yet identified and are usually linked to insulin resistance (IR). Acylation stimulating protein (ASP), a potent lipogenic factor, was recently shown to increase in patients with steatosis and was implicated in its pathogenesis. Aim. To investigate the association of plasma ASP levels with liver and metabolic risk markers in acute coronary syndrome (ACS) patients. Methods. 28 patients and 30 healthy controls were recruited. Their anthropometrics, lipid profile, liver markers, insulin, and ASP levels were measured. Results. In the patients, ASP, liver, and metabolic risk markers were markedly higher than in the controls. ASP strongly predicted GGT levels (B = 0.75, P < 0.0001), followed by triglycerides (B = 0.403, P = 0.017), together determining 57.6% variation in GGT levels. Insulin and IR correlated with metabolic risk components but not with liver enzymes. Conclusion. The strong association of ASP with GGT in ACS patients suggests that ASP, independent of IR, may contribute to a vicious cycle of hepatic lipogenic stimulation and GGT release promoting atherogenesis.

Inverse correlations between serum ADAMTS13 levels and systolic blood pressure, pulse pressure, and serum C-reactive protein levels observed at a general health examination in a Japanese population: a cross-sectional study

BACKGROUND

Although a defect in ADAMTS13 activity is known to cause platelet thrombosis resulting in thrombotic thrombocytopenic purpura (TTP), recent evidence has revealed that low plasma ADAMTS13 concentrations may increase the risk of ischemic vascular diseases. Furthermore, reduced plasma ADAMTS13 activity has been reported in acute systemic inflammation or sepsis. These findings prompted us to examine whether ADAMTS13 may play a role in more diverse diseases, not limited to TTP.

METHODS

A cross-sectional study was conducted to examine ADAMTS13 concentrations in blood samples from 432 subjects who had undergone a general health examination.

RESULTS

Serum ADAMTS 13 concentrations were lower in men than in women and in older age, as previously reported. Of note, the serum ADAMTS13 concentration was significantly and inversely correlated with the systolic blood pressure, pulse pressure, and serum C reactive protein concentration in both men and women and with the serum γ-glutamyltransferase concentration in men only. In 88 subjects, who underwent a carotid artery evaluation, serum ADAMTS13 concentrations were significantly lower in the subjects with a thicker carotid intima-media.

CONCLUSIONS

ADAMTS13 may play a role in not only TTP, but also inflammation, oxidative stress, and atherosclerosis. The potentially diverse clinical significance of ADAMTS13 should be prospectively elucidated in a larger cohort.

Serum levels of choline-containing compounds are associated with aerobic fitness level: the HUNT-study

Background

Cardiovascular disease (CVD) is a leading cause of death worldwide, and the number of people at risk is continuously growing. New methods for early risk prediction are therefore needed to actuate prevention strategies before the individuals are diagnosed with CVD. Several studies report that aerobic fitness level, measured as maximal oxygen uptake (VO_2max), is the single best predictor of future CVD mortality in healthy people. Based on this, we wanted to study differences between healthy individuals with a large difference in VO_2max-level to identify new biomarkers of low aerobic fitness that may also have potential as early biomarkers of CVD risk.

Methodology/Principal Findings

Serum samples from 218 healthy individuals with a low VO_2max (n = 108, 63 women) or high VO_2max (n = 110, 64 women) were analysed with MR metabolomics. In addition, standard clinical-chemical analyses for glucose, lipids, liver enzymes, micro-CRP, and colorimetric analysis on circulating choline were performed. Individuals in the low VO_2max-group had increased serum levels of free choline, decreased phosphatidylcholine, increased glucosę and decreased unsaturated fatty acids compared to the individuals in the high VO_2max–group.

Conclusions/Significance

Aerobic fitness dependent differences in serum levels of free choline and phosphatidylcholine are observed. They should be further studied as potential early markers of CVD risk.

The Association between Serum Gamma-Glutamyltransferase within Normal Levels and Metabolic Syndrome in Office Workers: A 4-Year Follow-up Study

Background

Serum gamma-glutamyltransferase (GGT) has been suggested as a predictor for development of the metabolic syndrome in non-Korean population, but studies in Korean population are scarce. Therefore, we examined the association between serum GGT levels and the incidence of the metabolic syndrome in Korean male office workers.

Methods

The study population consisted of 32,692 office workers who underwent health checkups in both 2005 and 2009. A total of 17,583 with elevated GGT levels, the presence of metabolic syndrome, medication history at baseline, and female office workers were excluded. Finally, 15,109 subjects were included in the final analysis. We measured serum GGT levels and individual metabolic components.

Results

As a quartile of serum GGT increased, 4-year follow-up incidence of the metabolic syndrome increased. After adjustment for age, alcohol drinking status and smoking status in 2005, logistic regression analysis showed that the odds ratios (95% confidence interval) for incident metabolic syndrome in 2009 compared to the lowest quartile and upper quartiles were 1.00 (reference), 1.57 (1.24-2.00), 2.73 (2.17-3.43), 3.78 (3.02-4.74), and statistically significant (P < 0.001), respectively.

Conclusion

These results showed that the higher serum GGT predicted the future development of metabolic syndrome. In Korean male office workers without the metabolic syndrome, the serum GGT levels despite normal levels were associated with an increased risk of incident metabolic syndrome.

Elevated serum γ-glutamyltransferase predicts the development of impaired glucose metabolism in middle-aged and elderly Chinese

The aim of this article is to prospectively investigate the association of the liver enzyme γ-glutamyltransferase (GGT) with the development of diabetes and impaired glucose regulation (IGR) in a Chinese population. Seven hundred and sixty normoglycaemic subjects aged 40 years or older randomly selected from an urban community of Shanghai received a baseline investigation in May 2005. The participants were invited to receive a standard 75-g oral glucose tolerance test (OGTT) in November 2008. Incident diabetes and IGR were determined according to the 1999 WHO criteria. Serum GGT levels were significantly associated with incident diabetes or combined diabetes and IGR prospectively. After extensive adjustment, the diabetes risk was significantly increased with incrementing serum GGT quartiles (P value for trend = 0.0027). As compared with the lowest quartile of GGT, the highest quartile had an adjusted hazard ratio of 1.30 (95% CI 1.03-1.65) for developing combined diabetes and IGR. Furthermore, a high serum GGT level at baseline was independently associated with an increase in the index of homeostasis model assessment of insulin resistance (HOMA-IR) at follow-up. Serum GGT concentration, even within its normal range, is a risk marker for developing impaired glucose metabolism in middle-aged and elderly Chinese.

Development and validation of a simple index system to predict nonalcoholic fatty liver disease

Background/Aims

Abdominal ultrasonography is useful for the detection and diagnosis of nonalcoholic fatty liver disease (NAFLD). The aims of this study were to establish a predictive model for the selection of subjects for abdominal ultrasonography for the diagnosis of NAFLD and to assess validity of the model.

Methods

The subjects included 901 people who visited the health examination center of the Busan Medical Center. We conducted multiple logistic regression analyses of potential risk factors to identify independent risk factors for NAFLD, and developed an index system.

Results

Four independent risk factors were identified. The index system was developed by assigning 1 clinical scoring point to approximately 0.7 logistic regression coefficients to each factor as follows: alanine aminotransferase/aspartate aminotransferase ratio >1.5 (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.21-4.07; P=0.010), 1 point; γ-glutamyl transpeptidase >50 (OR, 2.15; 95% CI, 1.13-4.07; P=0.019), 1 point; triglyceride >150 mg/dL (OR, 1.92; 95% CI, 1.14-3.24; P=0.015), 1 point; 23 kg/m²≤BMI<25 kg/m² (OR, 3.68; 95% CI, 2.05-6.63; P<0.001), 2 points; and BMI 25 kg/m² (OR, 7.65; 95% CI, 4.29-13.62; P<0.001), 3 points. The area under the receiver operating characteristics curve was 0.797 (95% CI, 0.751-0.842), and when 3 points was used as a cut-off value, the sensitivity and specificity were 71.7% and 75.9%, respectively.

Conclusions

NAFLD can be predicted through the clinical application of the index system established herein. If abdominal ultrasonography is used for high-risk patients, NAFLD will be diagnosed and managed in its early stage.

Association of serum alanine aminotransferase and γ-glutamyltransferase levels within the reference range with metabolic syndrome and nonalcoholic fatty liver disease

BACKGROUND/AIMS

Nonalcoholic fatty liver disease (NAFLD) has recently been found to be a novel component of metabolic syndrome (MS), which is one of the leading causes of chronic liver disease. The serum alanine aminotransferase (ALT) and ⟨-glutamyltransferase (GGT) levels are suggested to affect liver fat accumulation and insulin resistance. We assessed the associations of serum ALT and GGT concentrations within the reference ranges with MS and NAFLD.

METHODS

In total, 1,069 subjects enrolled at the health promotion center of Wonkwang University Hospital were divided into 4 groups according to serum ALT and GGT concentrations levels within the reference ranges. We performed biochemical tests, including liver function tests and lipid profiles, and diagnosed fatty liver by ultrasonography. Associations of ALT and GGT concentrationgrading within the reference range with fatty liver and/or MS were investigated.

RESULTS

The presence of MS, its components, and the number of metabolic abnormalities [except for high-density lipoprotein-cholesterol (HDL-C) and fasting blood glucose] increased with the ALT level, while the presence of MS, its components, and the number of metabolic abnormalities (except for HDL-C) increased with the GGT level. The odds ratios for fatty liver and MS increased with the ALT level (P⟨0.001 and P=0.049, respectively) and the GGT level (P=0.044 and P=0.039, respectively).

CONCLUSIONS

Serum ALT and GGT concentrations within the reference ranges correlated with the incidence of NAFLD and MS in a dose-dependent manner. There associations need to be confirmed in large, prospective studies.

Prevalence of Metabolic Syndrome According to Different Definitions in a Hypertensive Population

Aims: The metabolic syndrome (MetS) is associated with increased risk of cardiovascular disease (CVD) and diabetes mellitus (DM). Several definitions of MetS have been proposed. The aim of the present study was to estimate and compare the prevalence of MetS according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III), American Heart Association-National Heart Lung and Blood Institute (AHA-NHLBI), International Diabetes Federation (IDF) and the more recent Joint Interim Statement (JIS) definitions in patients attending a hypertension clinic. Methods: The records of patients referred to the hypertension clinic at the University Hospital (Heraklion, Crete) from January 2001 to June 2009 were screened retrospectively. A total 384 patients (146 men) were included in the study. Results: The prevalence of MetS according to the IDF and JIS definitions was significantly higher compared with that of the NCEP ATP III in both genders (IDF: P = .009 and P = .002, JIS: P = .002 and P = 0.001 for men and women, respectively); this was the case for the AHA-NHLBI definition only among women ( P = .03). All MetS components differed significantly ( P from < .0001 to .02) between patients with and without MetS for all definitions. Conclusions: The prevalence of MetS varies considerably depending on the definition used in a hypertensive population in a Mediterranean country. These differences will influence risk assessment.

Cross-sectional and longitudinal association of serum alanine aminotransaminase and γ-glutamyltransferase with metabolic syndrome in middle-aged and elderly Chinese people

BACKGROUND

Although associations of the liver enzymes alanine aminotransaminase (ALT) and γ-glutamyltransferase (GGT) with metabolic syndrome (MetS) are well recognized, whether they are independent of insulin resistance and which enzyme is more effective are yet to be clarified.

METHODS

A total of 5404 subjects aged ≥ 40 years were recruited from two urban communities in Shanghai for cross-sectional analyses. A subgroup of 681 participants without MetS at baseline was included in the longitudinal analyses. Insulin resistance was measured using the homeostasis model assessment of insulin resistance (HOMA-IR), and the modified National Cholesterol Education Program Adult Treatment Panel III criteria were adopted to diagnose MetS.

RESULTS

Both GGT and ALT were strongly and positively associated with MetS risks in simple and multivariate analyses. Further adjustment for HOMA-IR and ALT did not change the association of GGT and MetS materially, whereas adjustment for HOMA-IR and GGT substantially attenuated the ALT-MetS association. In longitudinal analyses, risks of developing MetS were increased across GGT quartiles in a dose-dependent manner after extensive adjustments (odds ratios were 1.00, 1.38, 1.62, and 2.29 for GGT, quartile 1 through quartile 4; P for trend = 0.01). In contrast, ALT was no longer associated with MetS development after final adjustment for GGT (P for trend = 0.09).

CONCLUSIONS

Our study confirmed significant and independent associations of GGT and ALT with MetS in adult Chinese people. Moreover, GGT might be more effective for indicating the future development of MetS.

[The association of central obesity with type 2 diabetes among Koreans according to the serum gamma-glutamyltransferase level: Korean genome and epidemiology study]

OBJECTIVES

This cross-sectional study was performed to examine if the serum gamma-glutamyltransferase (GGT) level that is within its normal range is associated with the risk of type 2 diabetes and if the association between the waist hip ratio (WHR) and type 2 diabetes is different depending on the serum GGT levels.

METHODS

The study subjects were 23,436 persons aged 40 years or older and who participated in regular health check-ups at 11 hospitals (males: 5,821, females: 17,615). The gender-specific quintiles of the serum GGT and WHR were used to examine the associations with type 2 diabetes.

RESULTS

The serum GGT levels within their normal range were positively associated with type 2 diabetes only in women. The adjusted odds ratios (ORs) were 1.0, 1.0, 1.4, 2.1, and 2.5 according to the quintiles of the serum GGT (p(trend)<0.01). The WHR was more strongly associated with the prevalence of diabetes among the women with a high-normal serum GGT level as compared with those with a low-normal serum GGT level (p for interaction=0.02). For example, the adjusted ORs for women with a low normal serum GGT level were 1.0, 1.2, 1.5, 2.2, and 2.4 according to the quintiles of the WHR, while those figures were 1.0, 2.4, 3.6, 5.0, and 8.3 among the women with a high normal serum GGT level. However, in men, the serum GGT was very weakly associated with type 2 diabetes and the association between the WHR and type 2 diabetes was not different depending on the serum GGT level.

CONCLUSIONS

Serum GGT within its normal range was positively associated with type 2 diabetes, and central obesity was more strongly associated with the prevalence of type 2 diabetes when the serum GGT level was high-normal. However, these associations were observed only in women, which is different from the previous findings. The stronger relation between central obesity and type 2 diabetes among women with a high-normal serum GGT level can be useful for selecting a group that is at high risk for type 2 diabetes irregardless of whatever the underlying mechanism is.

Pediatric nonalcoholic fatty liver disease: A clinical and laboratory challenge

The true prevalence of pediatric nonalcoholic fatty liver disease (NAFLD) is unknown. Challenges in determining the population prevalence of NAFLD include the type of test (and the reference intervals used to define normal and abnormal), the type of population (general population, hospital series), the demographic characteristics of the population sampled, and the nature of the study design. The natural history of pediatric NAFLD remains uncertain. The issue of when to perform a liver biopsy in children with suspected NAFLD remains controversial. Children with NAFLD but normal alanine aminotransferase are rarely investigated. However, evidence of alterations in glucose metabolism parameters should prompt a better understanding of the natural history of pediatric NAFLD not only in terms of the progression of liver disease but also regarding its potential relationship with other health outcomes such as type 2 diabetes mellitus and cardiovascular disease. This evidence could make liver biopsy mandatory in the majority of cases at risk of progressive and severe hepatic and extrahepatic disease. This conclusion, however, raises the question of the feasibility of liver biopsy assessment in an extremely large at risk population, and of the cost/effectiveness of this policy. There is a considerable, continuous interest in reliable, noninvasive alternatives that will allow the prognosis of pediatric NAFLD to be followed in large community or population-based studies.

Combination drug treatment in patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) includes simple steatosis, a benign condition, and non-alcoholic steatohepatitis, a condition that beyond TG accumulation also includes necroinflammation and fibrosis. An association between NAFLD and cardiovascular disease (CVD) has been recently suggested. NAFLD patients usually have an increased CVD risk profile. NAFLD is also associated with metabolic syndrome (MetS) and is considered as the hepatic component of MetS by some authors. Currently, the only established treatment of NAFLD is gradual weight loss. However, multifactorial treatment of NAFLD risk factors may be needed to reduce the increased CVD risk of NALFD patients. Drug combinations that include antiobesity drugs (such as orlistat and sibutramine) and target CVD risk factors may be a good approach to NAFLD patients. Our group has investigated the orlistat-fenofibrate combination treatment in obese patients with MetS and the orlistat-ezetimibe and sibutramine-antihypertensive combination treatment in obese patients with hyperlipidaemia with promising results in CVD risk factor reduction and improvement of liver function tests. Small studies give promising results but double-blind, randomized trials examining the effects of such multifactorial treatment in hard CVD endpoints in NAFLD patients are missing.

Application of five frozen human-pooled serum samples assigned by the International Federation of Clinical Chemistry and Laboratory Medicine reference procedure in a traceability investigation of γ-glutamyltransferase catalytic concentration measurements in China

Background

The in vitro directive of the European Union requires traceability to the international recommended reference procedures. The application of the reference procedures is necessary in order to evaluate the accuracy of γ-glutamyltransferase (GGT) assays of routine measurement systems in China.

Methods

Five frozen patient-pooled serum samples were assigned values by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) reference procedure in order to evaluate the traceability of the results of GGT catalytic activity from six homogeneous systems. One of the serum samples was used to calibrate seven non-homogeneous systems.

Results

All of the homogeneous systems, except the Dade system (Dade Bering Inc, IL, USA), achieved traceability within the measurement range. The Roche and Hitachi systems were better than the other systems. After calibration, the variance of the non-homogeneous systems decreased dramatically from between 14.50% and 25.23% to between 1.25% and 3.09% and the bias decreased from between −11.4% and −4.1% to between 0.5% and 3.5%.

Conclusion

Manufacturers in China should ensure that their calibration systems correspond to the IFCC reference procedures. Fresh frozen pooled patient serum assigned by reference laboratories can be used to calibrate non-homogeneous systems in order to achieve traceability.

Serum gamma-glutamyltransferase levels are related to insulin sensitivity and secretion in subjects with abnormal glucose regulation

BACKGROUND

To test the association between gamma-glutamyltransferase level and glucose regulation.

METHODS

We performed a cross-sectional analysis of 500 subjects [199 men/301 women, age 47 +/- 11 years, body mass index (BMI) 28.6 +/- 5.5 kg/m(2)] referred to Diabetes Clinics because of potential risk of type 2 diabetes mellitus (T2DM).

RESULTS

The prevalence of all glucose intolerance categories was higher in the top quartile of gamma-glutamyltransferase than in the first. Subjects with normal glucose tolerance showed lower gamma-glutamyltransferase levels compared with those with impaired glucose tolerance (IGT), impaired fasting glucose (IFG)+ IGT and T2DM (ANOVA, p < 0.0001), but not those with IFG. Homeostasis model assessment-insulin resistance (HOMA-IR) increased with increasing levels of gamma-glutamyltransferase, while the insulinogenic index/HOMA-IR ratio decreased. In an age- and sex-adjusted analysis, the top gamma-glutamyltransferase quartile was independently associated with IFG + IGT [odds ratio (OR) 2.41; 95% confidence interval (CI): 1.13-5.15] and T2DM (OR 2.77; 95% CI: 1.47-5.22). After further adjustment for BMI, alcohol intake, family history of diabetes, cigarette smoking and physical activity, the top quartile of gamma-glutamyltransferase remained an independent predictor of IFG + IGT (OR 2.62; 95% CI: 1.13-6.07) and T2DM (OR 2.39; 95% CI: 1.20-4.76). Only when transaminases and HOMA-IR have been added to the model, the top quartile of gamma-glutamyltransferase resulted no more independently associated to IFG + IGT or T2DM.

CONCLUSIONS

Gamma-glutamyltransferase is closely related to insulin resistance, reduced beta-cell function and deterioration of glucose tolerance.

Clinical risk factors for osteoporotic fracture: a population-based prospective cohort study in Korea

Clinical risk factors (CRFs), either alone or in combination with bone mineral density, are used to determine the fracture risk for clinical assessment and to determine intervention thresholds. Because fracture risk is strongly affected by ethnicity and population-specific differences, we sought to identify Korean-specific CRFs for fracture, in combination with quantitative ultrasound (qUS) measurements of the radius and tibia. A total of 9351 subjects (4732 men and 4619 women) aged 40 to 69 years were followed for a mean of 46.3 +/- 2.2 months. We obtained CRF information using a standardized questionnaire and measured anthropometric variables. Speed of sound at the radius (SoSR) and tibia (SoST) were measured by qUS. Fracture events were recorded using a questionnaire, and a height-loss threshold was used as an indicator of vertebral fracture. Relative risks were calculated by Cox regression analysis. A total of 195 subjects (61 men and 134 women) suffered low-trauma fractures. Older age, lower body mass index (BMI), and previous fracture history were positively associated with fracture risk in both sexes. Decreased hip circumference, lack of regular exercise, higher alcohol intake, menopause, and osteoarthritis history were further independent CRFs for fracture in women. However, neither SoSR nor SoST was independently associated with fracture risk. In this study, we identified the major Korean-specific CRFs for fracture and found that smaller hip circumference was a novel risk factor. This information will allow optimal risk-assessment targeting Koreans for whom treatment would provide the greatest benefit.

Increase in gamma-glutamyltransferase level and development of established cardiovascular risk factors and diabetes in Japanese adults

BACKGROUND

We investigated the predictive value of changes in serum gamma-glutamyltransferase (GGT) for the development of cardiovascular disease (CVD) risk factors in Japanese.

METHODS

A total of 1514 adult participants in a general health examination program were followed for 3 years until January, 2006. The subjects were divided into two groups according to whether their serum GGT level had decreased (< or =0 U/L) or increased (> or =1 U/L) from the baseline level of GGT during the study period. The logistic regression model was used to analyze the relationship between increases in GGT levels and the incidence of diabetes (DM), impaired fasting glucose (IFG), dyslipidemia, and hypertension (HT).

RESULTS

The mean value of GGT level was significantly higher at baseline than the 3-year follow-up point (47 +/- 41 versus 41 +/- 51, P < 0.0001), and the average 3-year GGT change was -5.7 +/- 32.3 U/L. The subjects with an increased GGT over the 3 years had an increased risk of developing DM, IFG, high triglyceride (TG) levels, and HT, in comparison with that of the subjects with a decreased GGT level, with an odds ratios (OR) of 6.13 (95% confidence interval [CI], 2.83-13.25), 2.70 (1.68-4.34), 2.65 (1.76-3.99), and 1.54 (1.12-2.13), respectively, after adjusting for age, sex, and alcohol habits. Further adjustments for baseline GGT, alanine aminotransferase (ALT), body mass index (BMI), and 3-year changes in BMI did not alter these associations.

CONCLUSIONS

The increased change in GGT over 3 years was a significant and an independent risk factor for the development of high TG, HT, IFG, and DM in Japanese.

Elevated serum alanine aminotransferase and gamma-glutamyltransferase and mortality in the United States population

BACKGROUND & AIMS

Elevated serum alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) activities are markers of liver injury, but may also be associated with other diseases and death. In a prospective, national, population-based sample, we examined whether elevated ALT and GGT were associated with increased risk of all-cause and disease-specific mortality.

METHODS

Death certificate-based 12-year mortality was analyzed among 14,950 adult participants in the third US National Health and Nutrition Examination Survey, 1988-1994, who were negative for markers of viral hepatitis B and C. Abnormal ALT was defined as >30 U/L in men or >19 U/L in women, and abnormal GGT as >51 U/L in men or >33 U/L in women.

RESULTS

Cumulative mortality was 13.9% from all causes, including 4.2% from cardiovascular disease, 4.2% from neoplasms, 0.44% from diabetes, and 0.13% from liver disease. In multivariate-adjusted analyses, elevated ALT was not associated with all-cause mortality (hazard ratio [HR], 1.2; 95% confidence interval [CI], 0.88-1.6). ALT elevation was associated with deaths from liver disease (HR, 8.2; 95% CI, 2.1-31.9), but not from cardiovascular disease (HR, 0.90; 95% CI, 0.56-1.4), neoplasms (HR, 1.0; 95% CI, 0.65-1.5), or diabetes (HR, 2.4; 95% CI, 0.65-9.1). All-cause mortality increased with elevated GGT (HR, 1.5; 95% CI, 1.2-1.8), as did mortality from liver disease (HR, 13.0; 95% CI, 2.4-71.5), neoplasms (HR, 1.5; 95% CI, 1.01-2.2), and diabetes (HR, 3.3; 95% CI, 1.4-7.6), but not from cardiovascular disease (HR, 1.3; 95% CI, 0.80-2.0).

CONCLUSIONS

In the US population, elevated GGT was associated with mortality from all causes, liver disease, cancer, and diabetes, while ALT was associated only with liver disease mortality.

A direct spectrophotometric gamma-glutamyltransferase inhibitor screening assay targeting the hydrolysis-only mode

Gamma-glutamyltransferase (GGT, E.C. 2.3.2.2) catalyzes the hydrolysis and transpeptidation of extracellular glutathione. Due to its central role in maintaining mammalian glutathione homeostasis, GGT is now believed to be a valuable drug target for a variety of life-threatening diseases, such as cancer. Unfortunately, however, effective tools for screening GGT inhibitors are still lacking. We report here the synthesis and evaluation of an alpha-phenylthio-containing glutathione peptide mimic that eliminates thiophenol upon GGT-catalyzed hydrolysis of the gamma-glutamyl peptide bond. The concurrent, real-time spectrophotometric quantification of the released thiophenol using Ellman's reagent creates a GGT assay format that is simple, robust, and highly sensitive. The versatility of the assay has been demonstrated by its application to the kinetic characterization of equine kidney GGT, and enzyme inhibition assays. The ability of the glutathione mimic to behave as an excellent donor substrate (exhibiting Michaelis-Menten kinetics with a K(m) of 11.3+/-0.5 microM and a k(cat) of 90.1+/-0.8 nmol mg(-1)min(-1)), coupled to the assay's ability to study the hydrolysis-only mode of the GGT-catalyzed reaction, make our approach amenable to high-throughput drug screening platforms.