Association between Gamma-Glutamyltransferase Level and Risk of Stroke: A Systematic Review and Meta-analysis of Prospective Studies

Long-Term Cumulative Exposure to High γ-Glutamyl Transferase Levels and the Risk of Cardiovascular Disease: A Nationwide Population-Based Cohort Study

BACKGRUOUND

Elevated γ-glutamyl transferase (γ-GTP) levels are associated with metabolic syndrome. We investigated the association of cumulative exposure to high γ-GTP with the risk of cardiovascular disease (CVD) in a large-scale population.

METHODS

Using nationally representative data from the Korean National Health Insurance system, 1,640,127 people with 4 years of consecutive γ-GTP measurements from 2009 to 2012 were included and followed up until the end of 2019. For each year of the study period, participants were grouped by the number of exposures to the highest γ-GTP quartile (0-4), and the sum of quartiles (0-12) was defined as cumulative γ-GTP exposure. The hazard ratio for CVD was evaluated using the Cox proportional hazards model.

RESULTS

During the 6.4 years of follow-up, there were 15,980 cases (0.97%) of myocardial infarction (MI), 14,563 (0.89%) of stroke, 29,717 (1.81%) of CVD, and 25,916 (1.58%) of death. Persistent exposure to high γ-GTP levels was associated with higher risks of MI, stroke, CVD, and death than those without such exposure. The risks of MI, stroke, CVD, and mortality increased in a dose-dependent manner according to total cumulative γ-GTP (all P for trend <0.0001). Subjects younger than 65 years, with a body mass index <25 kg/m2, and without hypertension or fatty liver showed a stronger relationship between cumulative γ-GTP and the incidence of MI, CVD, and death.

CONCLUSION

Cumulative γ-GTP elevation is associated with CVD. γ-GTP could be more widely used as an early marker of CVD risk, especially in individuals without traditional CVD risk factors.

Potential Causal Association between Elevated Gamma-Glutamyl Transferase Level and Stroke: A Two-Sample Mendelian Randomization Study

Researchers have suggested a potential relationship between gamma-glutamyl transferase (GGT) level and stroke. We investigated a potential causal relationship between GGT level as exposures and stroke and stroke subtypes (cardioembolic, small vessel, and large artery) in a European population. We performed a two-sample Mendelian randomization (MR) study using the genome-wide association study (GWAS) data from the UK Biobank as the exposure set. For the outcome set, we used stroke in the GWAS data from the GIGASTROKE Consortium. We considered alcohol consumption, atrial fibrillation, and body mass index as confounders. We used PhenoScanner searches for removal of SNPs and multivariable MR analysis for assessing confounders. We observed significant causal associations between GGT level and stroke (odds ratio [OR] = 1.23, 95% CI = [1.05-1.44], and p = 0.012 with IVW; OR = 1.19, 95% CI= [1.02-1.39], and p = 0.031 with MR-PRESSO). These results were consistent after removing SNPs related to confounding factors. Similarly, in multivariable MR, GGT was associated with stroke after adjusting for confounding factors (OR = 1.30, 95% CI 1.07-1.60), p = 0.010). Because GGT level has a causal relationship with stroke, researchers should test its significance as a potential risk factor for stroke. Additional research is required to validate these results.

Increased risk of ischemic stroke associated with elevated gamma-glutamyl transferase level in adult cancer survivors: a population-based cohort study

Adult cancer survivors may have an increased risk of developing ischemic stroke, potentially influenced by cancer treatment-related factors and shared risk factors with stroke. However, the association between gamma-glutamyl transferase (GGT) levels and the risk of ischemic stroke in this population remains understudied. Therefore, our study aimed to examine the relationship between GGT levels and the risk of ischemic stroke using a population-based cohort of adult cancer survivors. A population-based cohort of adult cancer survivors was derived from the National Health Insurance Service-Health Screening Cohort between 2003 and 2005 who survived after diagnosis of primary cancer and participated in the biennial national health screening program between 2009 and 2010. Cox proportional hazards model adjusted for sociodemographic factors, health status and behavior, and clinical characteristics was used to investigate the association between GGT level and ischemic stroke in adult cancer survivors. Among 3095 adult cancer survivors, 80 (2.58%) incident cases of ischemic stroke occurred over a mean follow-up of 8.2 years. Compared to the lowest GGT quartile, the hazard ratios (HRs) for ischemic stroke were 1.56 (95% CI 0.75-3.26), 2.36 (95% CI 1.12-4.99), and 2.40 (95% CI 1.05-5.46) for the second, third, and fourth sex-specific quartiles, respectively (Ptrend = 0.013). No significant effect modification was observed by sex, insurance premium, and alcohol consumption. High GGT level is associated with an increased risk of ischemic stroke in adult cancer survivors independent of sex, insurance premium, and alcohol consumption.

Association of gamma-glutamyl transferase variability with risk of venous thrombosis

Gamma-glutamyl transferase (GGT) is a biomarker of inflammation, and is known to be associated with stroke and atrial fibrillation. Venous thromboembolism (VT), a not uncommon thrombotic disorder, shares similar mechanisms with other thrombotic disorders including these stroke and atrial fibrillation. Given these associations, we intended to investigate the potential association between variability in GGT and VT. The study included data from the National Health Insurance Service-Health Screening Cohort, comprising 1,085,105 participants with health examinations 3 or more times from 2003 to 2008. Variability indexes were the coefficient of variation, standard deviation, and variability independent of the mean. The occurrence of venous thromboembolism (VT) was defined with more than one claim of the following ICD-10 codes: deep VT (I80.2-80.3), pulmonary thromboembolism (I26), intraabdominal venous thrombosis (I81, I82.2, I82.3), or other VT (I82.8, I82.9). To determine the relationship of quartiles of GGT with incident VT risk, Kaplan-Meier survival curve and logrank test were used. Cox's proportional hazard regression was used to investigate the risk of VT occurrence by GGT quartile (Q1-Q4). A total of 1,085,105 subjects were incorporated in the analysis, and the average follow-up was 12.4 years (interquartile range 12.2-12.6). VT occurred in 11,769 (1.08%) patients. The GGT level was measured 5,707,768 times in this stud. Multivariable analysis showed that GGT variability were positively associated with the occurrence of VT. Compared to the Q1, the Q4 showed an adjusted HR of 1.15 (95% CI 1.09-1.21, p < 0.001) when using coefficient of variation, 1.24 (95% CI 1.17-1.31, p < 0.001) when using standard deviation, and 1.10 (95% CI 1.05-1.16, p < 0.001) when using variability independent of the mean. Increased variability of GGT may be related to an increased risk of VT. Maintaining a stable GGT level would be beneficial in reducing the risk of VT.

Liver function parameters aspartate aminotransferase and total protein predict functional outcome in stroke patients with non-cardioembolism

Stroke, classified as cardioembolism and non-cardioembolism (non-CE), entails a large socioeconomic burden on the elderly. The morbidity and mortality of non-CE are high, whereas studies concerning prognostic factors impacting function outcome remain underdeveloped and understudied. Liver function parameters are convenient approaches to predicting prognosis in cardiovascular diseases, but their clinical significance has not been well characterized in stroke, especially in non-CE. In our study, a total of 576 patients with non-CE at 1 year of follow-up were enrolled in a cohort from a consecutive hospital-based stroke registry, with randomly 387 patients as the development cohort and 189 patients as the validation cohort. The univariate and multivariate analyses revealed the following novel findings: (i) The incidence of unfavorable functional outcomes after non-CE was significantly greater (p &lt; 0.01) in patients with higher age, aspartate aminotransferase (AST), the National Institutes of Health Stroke Scale (NIHSS) score, and depressed total protein (TP); (ii) We established a novel model and nomogram to predict stroke prognosis, in addition to the known factors (age and the NIHSS score). The levels of AST and TP were independently correlated with the incidence of unfavorable outcomes [AST: odds ratio (OR) = 1.026, 95% CI (1.002–1.050); TP: OR = 0.944, 95% CI (0.899–0.991)]; (iii) The results persisted in further subgroup analysis stratified by age, gender, the NIHSS score, and other prespecified factors, especially in males 60 years or older. Overall, this study demonstrates that hepatic parameters (AST and TP) after non-CE are considered to be associated with functional outcomes at 1-year follow-up, especially in males aged ≥ 60 years.

Elevated gamma‐glutamyl transferase levels are associated with stroke recurrence after acute ischemic stroke or transient ischemic attack

Aims

Methods

Results

Conclusion

Cross-sectional association between gamma-glutamyl transferase and hyperuricaemia: the China Multi-Ethinic Cohort (CMEC) study

OBJECTIVES

Several studies have demonstrated the association between gamma-glutamyl transferase (GGT) and hyperuricaemia, but little is known about such relation in less-developed ethnic minority regions.

DESIGN

We cross-sectionally analysed data from the China Multi-Ethnic Cohort (Yunnan region).

SETTING

Cross-sectional study.

PARTICIPANTS

22 020 participants aged 30-79 years from Han ethnicity, Yi ethnicity and Bai ethnicity.

OUTCOMES

The serum level of uric acid, GGT and other metabolic parameters were tested. Weight, height and blood pressure were measured. Smoking, drinking, ethnicity, education and medical history were obtained from questionnaires.

RESULTS

In the crude model, compared with the lowest quintile, the second, third, fourth and fifth quintiles of serum GGT exhibited a positive association with hyperuricaemia risk (OR=1.69, 2.90, 4.34 and 7.70, 95% CI=1.42 to 2.01, 2.47 to 3.42, 3.71 to 5.09 and 6.60 to 8.98, respectively, p-trend<0.0001). In fully adjusted model, compared with the lowest quintile, the second, third, fourth and fifth quintiles of serum GGT also exhibited a positive association with hyperuricaemia risk (OR=1.26, 1.68, 2.02 and 3.02, 95% CI=1.04 to 1.51, 1.40 to 2.00, 1.69 to 2.42 and 2.51 to 3.64, respectively, p-trend<0.0001). Logistic regression model was conducted separately in ethnic groups. Compared with first quintile, the highest GGT level were related to higher risk of hyperuricaemia in three ethnic groups (OR (95% CI): 2.89 (2.26 to 3.68), 2.81 (1.93 to 4.11) and 3.04 (1.91 to 4.84) for Han, Yi and Bai ethnicity, respectively, p-trend <0.0001). The relationship between GGT and hyperuricaemia was also observed in different age groups or gender groups.

CONCLUSIONS

High serum GGT level was related to a higher risk of hyperuricaemia in less-developed ethnic minority regions in China.

Obese Vegetarians and Omnivores Show Different Metabolic Changes: Analysis of 1340 Individuals

Our study evaluated the association between the increase in body mass index (BMI) in men and women (menstruating and non-menstruating) (n = 1340) with different dietary groups (omnivores, semi-vegetarians, lacto-ovo-vegetarian, and vegans) and the measurement of the biochemical markers high-sensitive C-reactive protein (hs-CRP), ferritin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), glycated hemoglobin (HbA1C), and insulin resistance index (HOMA-IR). Increasing BMI values in all groups and dietary profiles were related to a significant increase in hs-CRP (p < 0.0001), ALT (p = 0.02), ferritin (p = 0.009), and HbA1C (p < 0.0001), with no difference between dietary groups (p < 0.05). The increase in BMI increases the levels of HOMA-IR (p < 0.0001) and GGT (p < 0.05), with higher values found in men when compared to women (p < 0.0001 for HOMA- IR and p = 0.0048 for GGT). The association between ALT and BMI was different between dietary groups, as it showed a decrease in vegan women who do not menstruate compared to other dietary groups (p = 0.0099). When including only obese individuals (BMI ≥ 30 kg/m2, n = 153) in the analysis, we observed lower concentrations of GGT and ferritin in vegetarians than in omnivores, regardless of gender and menstrual blood loss (p = 0.0395). Our data showed that for both vegetarians and omnivores, the higher the BMI, the worse the metabolic parameters. However, regarding obesity, vegetarians showed better antioxidant status (lower GGT elevation) and lower inflammatory status (lower ferritin elevation), which may provide them with potential protection in the development of morbidities associated with overweight.

Liver enzymes and risk of ocular motor cranial nerve palsy: a nationwide population-based study

This study aimed to assess the associations between liver enzymes including γ-glutamyl transferase (GGT) and the development of ocular motor cranial nerve palsy (CNP) using the National Sample Cohort database from Korea's National Health Insurance Service. We analyzed data from 4,233,273 medical screening examinees aged 20 years or more in 2009. Study participants were followed up until December 31, 2018. A Cox proportional hazard regression analysis was performed for quartiles of liver enzymes to determine the linkage between each value and ocular motor CNP using quartile 1 as a reference after adjusting for potential confounders. A total of 5,807 (0.14%) patients developed ocular motor CNP during the follow-up period of 8.22 ± 0.94 years. The incidence of ocular motor CNP gradually increased as the GGT levels increased. The highest quartile of the GGT group had hazard ratio (HR) of 1.245 (95% confidence interval [CI], 1.136-1.365). Regarding alanine aminotransferase (ALT), the highest quartile of the ALT group had HR of 1.141 (95% CI, 1.049-1.241). However, the incidence of ocular motor CNP did not gradually increase as the ALT levels increased. The coexistence of the increased level of GGT, metabolic syndrome, and obesity showed a stronger association with ocular motor CNP development (HR, 1.331; 95% CI, 1.173, 1.511) compared to having a single factor or two factors. In conclusion, our population-based cohort study demonstrated a significant association between serum GGT level and the incidence of ocular motor CNP, suggesting that GGT could be a new clinical marker for predicting the occurrence of ocular motor CNP.

Increased concentration of serum gamma-glutamyl transferase in ischemic stroke patients

BACKGROUND:

Stroke is responsible for the largest proportion of neurological disorders causing a significant morbidity. Gamma-glutamyl transferase (GGT) enzyme has an active involvement in atherosclerosis through its role in oxidative and inflammatory mechanisms. Recent evidence suggests that serum GGT is related to the risk and prognosis of cerebrovascular diseases.

METHODS:

A total of 200 patients (100 with acute ischemic stroke and 100 without stroke) were recruited from various medical wards and medical intensive care unit. Categorical variables were compared between two groups using Chi-squared test and odds ratio (OR). Independent sample t-test was used to see to compare mean GGT level of stroke patients with control.

RESULTS:

There was no statistical difference with respect to distribution of age groups (χ² = 1.25, P = 0.741) and gender (χ² = 2.678, P = 0.1018) between cases and controls. Mean age of stroke patients (mean [M] = 61.7, standard deviation [SD] = 13.8) did not differ from controls (M = 62.2, SD = 13.6), P = 0.80. The odds of suffering from diabetes were significantly higher in stroke patients than cases (OR = 2.25, P = 0.005). Independent sample t-test found a significant difference in serum GGT level between cases (M = 57.47, SD = 11.8) and control (M = 41.72, SD = 7.5), P ≤ 0.0001.

CONCLUSIONS:

Serum GGT was significantly higher in stroke patients than age-sex-matched nonstroke patients. Association remained significant in stroke patients irrespective of age, gender, and other risk factors. Stroke patients with diabetes, hypertension, dyslipidemia, obesity, and smoking had higher level serum GGT level than those without these risk factors. Prospective cohort studies can further explore the potential of GGT as a predictor of acute ischemic stroke.

Prognostic value of long-term gamma-glutamyl transferase variability in individuals with diabetes: a nationwide population-based study

We examined whether long-term gamma-glutamyl transferase (GGT) variability can predict cardiovascular disease (CVD) and mortality in individuals with diabetes. We included 698,937 Koreans diabetes patients older than 40 years without histories of CVD, chronic liver disease, or heavy alcoholics who received health exams supported by the Korean government more than once in 2009-2012 (baseline). We used Cox proportional analyses to estimate the risk of stroke, myocardial infarction (MI), and all-cause mortality until December 31, 2016, according to the quartiles of the average successive variability (ASV) of GGT measured during the five years before the baseline. A total 26,119, 15,103, and 39,982 cases of stroke, MI, and death, respectively, were found. GGT ASV quartile 4 had a significantly higher risk of stroke and all-cause mortality than quartile 1, with adjustment for risk factors, such as baseline glucose and GGT level, and comorbidities. Hazard ratios (95% confidence intervals) for GGT ASV quartile 4 were 1.06 (1.03-1.10) and 1.23 (1.20-1.27) for stroke and mortality, respectively. This significant association was shown consistently across the baseline GGT quartiles. GGT variability was related to the risk of stroke and all-cause mortality. The effect was most pronounced in all-cause mortality, irrespective of baseline GGT level.

Early Biomarkers of Neurodegenerative and Neurovascular Disorders in Diabetes

Diabetes mellitus (DM) is a common disease worldwide. There is a strong association between DM and neurovascular and neurodegenerative disorders. The first group mainly consists of diabetic retinopathy, diabetic neuropathy and stroke, whereas, the second group includes Alzheimer's disease, Parkinson's disease, mild cognitive impairment and dementia. The aforementioned diseases have a common pathophysiological background including insulin resistance, oxidative stress, atherosclerosis and vascular injury. The increasing prevalence of neurovascular and neurodegenerative disorders among diabetic patients has resulted in an urgent need to develop biomarkers for their prediction and/or early detection. The aim of this review is to present the potential application of the most promising biomarkers of diabetes-related neurodegenerative and neurovascular disorders, including amylin, β-amyloid, C-reactive protein (CRP), dopamine, gamma-glutamyl transferase (GGT), glycogen synthase kinase 3β, homocysteine, microRNAs (mi-RNAs), paraoxonase 1, phosphoinositide 3-kinases, tau protein and various growth factors. The most clinically promising biomarkers of neurovascular and neurodegenerative complications in DM are hsCRP, GGT, homocysteine and miRNAs. However, all biomarkers discussed in this review could become a part of the potential multi-biomarker screening panel for diabetic patients at risk of neurovascular and neurodegenerative complications.

Serum Gamma-Glutamyltransferase, Daily Alcohol Consumption, and the Risk of Chronic Kidney Disease: The Kansai Healthcare Study

BACKGROUND

Serum gamma-glutamyltransferase has been recognized as the risk factor of cardiovascular and metabolic diseases. However, the association between serum gamma-glutamyltransferase and the risk of chronic kidney disease is not well known, and no prospective studies have examined separately the relationship of serum gamma-glutamyltransferase with the risk of proteinuria versus that of low estimated glomerular filtration rate (eGFR).

METHODS

We prospectively followed 9,341 Japanese men who did not have low eGFR, proteinuria, or diabetes, and did not take antihypertensive medications at entry for the analysis of proteinuria, and we followed 9,299 men for the analysis of low eGFR. We defined "persistent proteinuria" as proteinuria detected two or more times consecutively and persistently as ≥1+ on urine dipstick at the annual check-up until the end of follow-up. Low eGFR was defined as eGFR <60 mL/min/1.73 m².

RESULTS

During the 11-year observation period, 151 men developed persistent proteinuria and 1,276 men developed low eGFR. In multivariate models, the highest quartile (≥71 IU/L) of serum gamma-glutamyltransferase was independently related to the development of persistent proteinuria (hazard ratio 3.39; 95% confidence interval, 1.92-5.97) compared with the lowest quartile (≤25 IU/L). In joint analysis of alcohol consumption and serum gamma-glutamyltransferase, non-drinkers in the highest tertile (≥58 IU/L) of serum gamma-glutamyltransferase had the highest risk of persistent proteinuria. However, there was no association between serum gamma-glutamyltransferase and low eGFR.

CONCLUSION

In middle-aged Japanese men, elevated serum gamma-glutamyltransferase was independently associated with future persistent proteinuria, but not with low eGFR.

Association between Serum Gamma-glutamyl transferase and Intracranial Arterial Calcification in Acute Ischemic Stroke Subjects

Intracranial artery calcification (IAC) is an important risk factor for cerebral infarction and a key biomarker for intracranial artery stenosis. Gamma-glutamyl transferase (GGT) has been independently associated with increased cardiovascular events and coronary calcification. Our study assessed whether GGT is an independent factor for IAC in acute ischemic stroke (AIS) patients. This cross-sectional study involved a total of 754 patients with AIS (mean age: 65 ± 13.2 years). All the patients had received brain computed tomography angiography (CTA) examination to evaluate IAC. Further, serum GGT levels and other biochemical parameters were analyzed. The average GGT level in patients who died was also significantly increased (37.0 ± 26.8 vs 29.0 ± 21.5 U/L, p = 0.012). Partial correlation analysis showed that serum GGT levels were associated with NIHSS score at admission after adjustment for age and gender was considered (r = 0.150, p = 0.001). Logistic regression analysis showed that serum GGT levels independently predicted all-cause mortality (OR = 1.036, 95% CI: 1.014-1.060, p = 0.002), NIHSS scores (β = 0.051, 95% CI: 0.020-0.082, p = 0.001) and IAC scores (β = 0.006, 95% CI: 0.003-0.014, p = 0.005) in male patients. Each SD (standard deviation) increase of serum GGT levels was also associated with risk of all-cause mortality (OR = 2.272, 95% CI: 1.364-3.787, P = 0.002). GGT levels in patients with severe IAC were significantly elevated (37.6 ± 33.6 vs 28.6 ± 19.2, p < 0.001). However, serum GGT levels could not independently predict the severity of IAC in AIS patients. Our study identified that serum GGT levels were significantly elevated in patients who died, and the GGT levels had a certain association with the risk of death and IAC in male patients.

Dose-response relationship between gamma-glutamyltransferase and the risk of atherosclerotic cardiovascular diseases in Korean adults

BACKGROUND AND AIMS

The value of gamma-glutamyltransferase (GGT) in the putative mechanisms underlying its association with cardiovascular disease is unclear. This study examined whether serum GGT value has an independent association and dose-response relationship with the risk of atherosclerotic cardiovascular disease (ASCVD).

METHODS

This observational study included 419,433 subjects from the National Health Insurance Service database. Serum GGT levels were classified into sex-specific quartiles. We used Cox proportional hazard models to examine the effect of serum GGT values on the risk of ASCVD. We quantified associations of the serum GGT quartile groups with risk of ASCVD or each subtype through multivariate sub-distribution hazard models adjusted for covariates at baseline.

RESULTS

During 4,572,993.8 person-years of follow-up for ASCVD, we documented 40,359 (9.6%) incident cases of ASCVD. The highest serum GGT group had a significant association with ASCVD in contrast to the lowest serum GGT quartile group (hazard ratio [HR] = 1.23, 95% confidence interval [CI] = 1.19-1.27). Serum GGT quartile groups 2, 3, and 4 had a significantly higher risk for incident hemorrhagic stroke than the serum GGT quartile group 1 (Q 2: HR = 0.92, 95% CI = 0.83-1.02; Q 3: HR = 1.03, 95% CI = 0.93-1.15; Q 4: HR = 1.29, 95% CI = 1.16-1.42; p for trend <0.001). For ischemic heart disease (IHD) and myocardial infarction, non-linear trends were shown according to increasing log-transformed GGT values. In the dose-response trends to assess the interaction effect of obese status, differences of trends were shown between serum GGT level and IHD or hemorrhagic stroke.

CONCLUSIONS

The serum GGT value, which is known as a factor linked to cardiovascular diseases, has a strong independent association and dose-response relationship with hemorrhagic stroke risk in contrast to that with ischemic stroke or IHD.

Non-alcoholic fatty liver disease, liver biomarkers and stroke risk: The Reasons for Geographic and Racial Differences in Stroke cohort

Background and purpose

Liver disease, particularly non-alcoholic fatty liver disease (NAFLD), is a risk factor for cardiovascular disease, but little is known about its relationship with ischemic stroke.

Methods

In the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort of 30,239 American black and white adults, we assessed baseline NAFLD as fatty liver index (FLI) >60, and assessed liver biomarkers aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyl transpeptidase (GGT), and the AST/ALT ratio and risk of incident ischemic stroke over 5.8 years using a case-cohort study design.

Results

Considering 572 strokes and a 1,017-person cohort sample, NAFLD was inversely associated with stroke risk in men (HR: 0.50; 95% CI: 0.26, 0.96), as was being in the highest ALT quintile versus the lowest (HR: 0.39; 95% CI: 0.19, 0.78) and the highest versus lowest GGT quintile (HR: 0.45, 95% CI: 0.24, 0.85), but not in women. Conversely, FLI score above the 90^th percentile was associated with increased stroke risk among women (HR: 2.26; 95% CI: 1.14–4.47), but not men. AST was not associated with stroke risk in either sex. AST/ALT ratio >2 was strongly associated with increased stroke risk in whites, but not blacks (HRs: 3.64; 95% CI: 1.42–9.35 and 0.97; 95% CI: 0.45–1.99, respectively; p for interaction = 0.03).

Conclusions

The relationships between NAFLD, liver biomarkers, and ischemic stroke are complex, and sex and race differences we observed require further study and confirmation.

Implication of liver enzymes on incident cardiovascular diseases and mortality: A nationwide population-based cohort study

Although liver enzymes, such as γ-glutamyltransferase (GGT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), have recently been suggested as risk factors for cardiovascular diseases (CVD), impact on mortality after myocardial infarction (MI) or ischemic stroke (IS) was not previously examined. Using a population-based, nationwide cohort database, we explored the implication of GGT and aminotransferases on the development of CVD and all-cause mortality during a median 9.1 years of follow-up. Among 16,624,006 Korean adults, both GGT and aminotransferases exhibited a positive relationship with MI, IS, and mortality in a multivariate adjusted model. ALT and AST showed U-shaped associations with mortality, whereas GGT showed a positive linear relationship with mortality. The risk of 1-year mortality after MI or IS was significantly higher in the highest quartile of GGT compared to the lowest quartile (HR, 1.46; 95% CI, 1.40-1.52). The implication of GGT on MI, IS, and mortality persisted regardless of traditional cardiovascular risk parameters. This study demonstrated the unique pattern of association of ALT, AST, and GGT with the development of CVD and all-cause mortality in the Korean population. In particular, GGT showed the most robust linear relationship with mortality before and after cardiovascular events independent of risk factors.

Gamma-glutamyltransferase-friend or foe within?

Gamma-glutamyltransferase (GGT) is a liver enzyme, which is located on the plasma membranes of most cells and organ tissues, but more commonly in hepatocytes, and is routinely used in clinical practice to help indicate liver injury and as a marker of excessive alcohol consumption. Among the liver enzymes, important advances have especially been made in understanding the physiological functions of GGT. The primary role of GGT is the extracellular catabolism of glutathione, the major thiol antioxidant in mammalian cells, which plays a relevant role in protecting cells against oxidants produced during normal metabolism; GGT, therefore, plays an important role in cellular defence. Beyond its physiological functions, circulating serum GGT has been linked to a remarkable array of chronic conditions and diseases, which include nonalcoholic fatty liver disease, vascular and nonvascular diseases and mortality outcomes. This review summarizes the available epidemiological and genetic evidence for the associations between GGT and these adverse outcomes, the postulated biologic mechanisms underlying these associations, outlines areas of outstanding uncertainty and the implications for clinical practice.