Alanine aminotransferase and the 6-year risk of the metabolic syndrome in Caucasian men and women: the Hoorn Study

Aminotransferases as causal factors for metabolic syndrome: A bidirectional Mendelian randomization study

BACKGROUND

Circulating aminotransferases (ALT and AST) have been used as biomarkers for liver injury. The causal relationships between aminotransferases and metabolic syndrome remain ambiguous.

METHODS

We conducted bidirectional and multivariable Mendelian randomization (MR) analyses between aminotransferases and traits related to metabolic syndrome using genetic variants obtained from genome-wide association studies (GWASs). MR-PRESSO tests were adopted to remove outliers and eliminate pleiotropy. MR steiger tests were conducted to ensure the correct direction of the causal effects.

RESULTS

Both aminotransferases were risk factors for essential hypertension. ALT is a risk factor for type 2 diabetes. The bidirectional causal relationship between ALT and hyperglycemia, serum lipids, and obesity was demonstrated. The effect of fasting glucose on AST was demonstrated, while type 2 diabetes did not affect AST. The effect of HDL-C on ALT and the effect of triglycerides on AST were found in multivariable MR analyses.

CONCLUSIONS

Our bidirectional MR analyses suggest that ALT and AST are causally associated with several metabolic syndrome-related traits, especially hypertension and type 2 diabetes. These findings highlight the potential role of aminotransferases as biomarkers and therapeutic targets for metabolic syndrome.

Individual and combined relationship of serum uric acid and alanine aminotransferase on metabolic syndrome in adults in Qingdao, China

BACKGROUND AND AIMS

Associations of alanine aminotransferase (ALT) and serum uric acid (SUA) with metabolic syndrome (MetS) remain controversial. We aimed to explore individual and combined effects of ALT and SUA on MetS in community residents.

METHODS AND RESULTS

A population-based cross-sectional survey involving randomly selected Chinese adults aged 35-74 years was conducted in 2009 in Qingdao, China, and 4642 participants were included in the current study. Based on a combination of SUA and ALT levels in the tertile, subjects were grouped into Group 1-9. The individual and combined relations of SUA and ALT to MetS were analyzed by logistic regression models. The prevalence of MetS was 28.50% in males and 22.30% in females. ALT and SUA were independently associated with MetS and ORs (95% CIs) were 1.55 (1.42-1.70) and 1.92 (1.72-2.14), respectively, after adjusting for potential confounders. With the elevation of ALT and SUA levels, the risk of developing MetS increased. Compared to Group 1, ORs (95% CIs) of combined ALT and SUA for MetS were 2.21 (1.70-2.88), 4.02 (3.10-5.21), 2.19 (1.62-2.97), 2.53 (1.91-3.34), 4.69 (3.60-6.12), 1.76 (1.17-2.64), 3.65 (2.63-5.06) and 7.15 (5.41-9.46) in Group 2-9, respectively.

CONCLUSIONS

ALT and SUA were both related to MetS independently. Combined elevation of ALT and SUA levels could increase the risk of MetS and its components than an elevation in SUA and ALT alone. Therefore, measures should be taken to lower SUA and ALT levels to reduce the risk of having MetS.

Association between liver enzymes and metabolic syndrome in Canadian adults: results from the Canadian health measures survey - cycles 3 &4

Background

The relationship between liver enzymes and Metabolic Syndrome (MetS) in different populations, including Canadians, is not consistent and well understood. We used the Canadian Health Measures Survey data (Cycles 3 and 4) to examine the cross-sectional relationships between select liver biomarkers and MetS in the adult Canadian population. The biomarkers selected were gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), and alkaline phosphatase (ALKP).

Methods

Fasting blood samples (FBS) were collected from adults above the age of 20 years for Cycle 3 and Cycle 4 (n = 3003). MetS was diagnosed if the subjects had three or more risk determinants according to the Joint Interim Statement criteria. Primary risk factors included quartile cut-offs for each of the biomarkers ALKP, AST, GGT for males and females separately. A multivariable logistic regression technique based on a maximum likelihood approach was used to evaluate the association between quartiles of ALKP, AST, and GGT, other individual and contextual factors, and the prevalence of MetS.

Results

MetS was prevalent in 32.3% of subjects. BMI was an effect modifier in the relationship between GGT and MetS prevalence, while sex was an effect modifier in the relationship between ALKP and MetS prevalence; and age was an effect modifier in the relationship between AST and MetS prevalence.

Conclusions

Since the mechanisms to underpin the associations between the liver enzymes activity and MetS are unknown, further epidemiologic investigations using longitudinal designs are necessary to understand these associations.

Gamma-glutamyl transpeptidase elevation is associated with metabolic syndrome, hepatic steatosis, and fibrosis in patients with nonalcoholic fatty liver disease: A community-based cross-sectional study

This study aimed to analyze the association between elevated gamma-glutamyl transpeptidase (GGT) and metabolic syndrome (MetS), hepatic steatosis, and fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). From August 2013 to August 2018, a community-based study was conducted in the northeastern part of Taiwan. Patients who underwent abdominal ultrasonography (US) and had no history of alcoholic liver disease were included. According to a US examination showing fatty liver degree, 1566 patients with NAFLD were divided into four groups: normal GGT, isolated GGT elevation, isolated alanine aminotransferase (ALT) elevation, and both GGT and ALT elevation groups. Further 1147 participants with normal serum ALT, GGT, and the abdominal US were included as the control group. GGT levels were associated with high sensitivity C-reactive protein, lower adiponectin, diabetes mellitus, and chronic kidney disease. A stepwise increase in odds ratio (OR) for MetS was found in the normal GGT group (OR = 1.71), isolated GGT elevation group (OR = 3.06), isolated ALT elevation (OR = 4.00), and both GGT + ALT elevation group (OR = 4.17) than the control group. Linear regression analysis revealed a positive association between GGT/ALT value and hepatic steatosis degree, GGT value, and degree of hepatic fibrosis. Hence, GGT elevation is associated with MetS, hepatic steatosis, and fibrosis in patients with NAFLD.

Exploratory metabolomics of metabolic syndrome: A status report

Metabolic syndrome (MetS) is as a cluster of cardio-metabolic factors that greatly increase the risk of chronic diseases such as type II diabetes mellitus and atherosclerotic cardiovascular disease. In the United States, obesity, physical inactivity, aging, and genetics (to a minor extent) have arisen as risk factors for developing MetS. Although 35% of American adults suffer from MetS, its pathogenesis largely remains unknown. Worse, there is a lack of screening and optimum therapy for this disease. Researchers have consequently turned towards metabolomics to identify biomarkers to better understand MetS. The purpose of this review is to characterize various metabolites and their potential connections to MetS. Numerous studies have also characterized MetS as a disease of increased inflammation, and therefore this review also explores how metabolites play a role in various inflammatory pathways. Our review explores a broad range of metabolites including biogenic amines, branched chain amino acids, aromatic amines, phosphatidylcholines, as well as a variety of other molecules. We will explore their biochemical pathways and their potential role in serving as biomarkers.

The relationship of alanine aminotransferase to metabolic syndrome in a Korean population

BACKGROUND/AIMS

Although associations between serum alanine aminotransferase and metabolic syndrome are well-recognized in Western countries, only a limited number of prospective studies have been performed in Asian populations. The aim of the study was to cross-sectionally and longitudinally examine whether serum alanine aminotransferase levels are associated with metabolic syndrome and its associated components in a Korean population.

MATERIALS AND METHODS

A total of 31,832 subjects who received health screenings were included in cross-sectional analyses; a subgroup of 4.070 subjects without metabolic syndrome at baseline was included in the longitudinal analyses. The metabolic syndrome definition was based on the National Cholesterol Education Program Third Adult Treatment Panel criteria with modification on waist circumference cut-off to be more appropriate for an Asian population.

RESULTS

In the cross-sectional analyses, serum alanine aminotransferase is positively associated with metabolic syndrome and its components. In the longitudinal analyses, the prevalence of metabolic syndrome increased across serum alanine aminotransferase quartiles in a dose-dependent manner after extensive adjustments (hazard ratios were 1.000, 1.609, 2.601, and 3.015 for quartiles, 1 through quartile 4; P for trend<0.001).

CONCLUSION

Our study confirmed a positive association between components of metabolic syndrome and elevated serum alanine aminotransferase in a Korean population.

Association between Serum Liver Enzymes and Metabolic Syndrome in Korean Adults

The purpose of this study was to evaluate the association between alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and metabolic syndrome (MS) in the Korean population. A total of 11,587 adults ≥30 years of age and with complete data were selected from Korea National Health and Nutrition Examination Survey VI conducted from 2013 to 2015. Normal ALT and AST levels were divided into quartiles, and their associations with MS were assessed by logistic regression analysis. Elevated levels of ALT [adjusted odds ratio (aOR) = 7.90, 95% confidence interval (CI) = 6.50–9.60] and AST (aOR = 3.81, 95% CI = 3.10–4.74) were both significantly associated with a higher prevalence of MS. The quartile group containing the highest levels of ALT and AST within the normal range also showed an increased risk of MS and its components. Elevated levels of ALT and AST, even within the normal range, were associated with prevalence of MS.

Is within-normal range liver enzymes associated with metabolic syndrome in adults?

BACKGROUND

Considering the clear association between metabolic syndrome and future cardiovascular disease, early detection of metabolic syndrome is important. This study was conducted to assess the correlation between metabolic syndrome components and within-normal-range of liver enzymes in Iranian adults.

METHODS

This cross-sectional study was comprised of 700 Iranian adults in the districts of East Azerbaijan-Iran in 2015. The levels of lipid profile and glucose were measured by enzymatic colorimetric methods. Weight, height, waist circumferences were measured with standard protocols. Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) were assessed using the ultraviolet method. The Pearson correlation and Logistic regression were used to for statistical analysis.

RESULTS

With increasing the number of metabolic abnormalities, the mean ALT level was increased significantly (P_trend=0.04). In women, the increase in AST and ALT with increasing the number of metabolic abnormalities was statistically significant (P_AST=0.01; P_ALT<0.001). In men, ALT level had significantly positive correlation with waist circumference (r=0.14, P<0.05), serum TG (r=0.16, P<0.05) and fasting plasma glucose (r=0.17, P<0.01). In women, there was a significant correlation between AST level and serum TG (r=0.15, P<0.05). A significant positive and negative correlation were found respectively between serum ALT and AST/ALT ratio and waist circumference, serum TG and fasting blood glucose. Women in the 4th quartile of ALT were 4.43 fold at an increased risk for metabolic syndrome outcome when compared to those in the first quartile [OR (95% CI): 4.43 (1.69, 11.63)]. In women, with increasing the quartiles of ALT within normal limits, the percent of participants with metabolic syndrome also increased significantly (P_trend=0.04).

CONCLUSIONS

Based on the results, the use of ALT and AST:ALT ratio as continuous biomarkers for early signaling of dysmetabolism especially in women could be encouraged.

High serum alanine aminotransferase is associated with the risk of colorectal adenoma in Korean men

BACKGROUND AND AIM

An elevated alanine aminotransferase (ALT) is frequently observed in subjects with metabolic syndrome, which is associated with the risk of colorectal adenoma (CRA). However, the relationship between ALT and CRA remains unclear. Therefore, we aimed to investigate whether high serum ALT is associated with the risk of CRA in a metabolically healthy population.

METHODS

We conducted this cross-sectional study in 27,717 asymptomatic Korean adults who underwent a health checkup. Subjects were categorized as adenoma-free, hyperplastic polyp, low-risk adenoma, or high-risk adenoma. High-risk adenoma was defined as three or more adenomas, any adenoma ≥ 10 mm, or adenoma with high-grade dysplasia or villous features.

RESULTS

Among all participants, 10.3% and 1.5% of cases were categorized as low-risk and high-risk adenoma, respectively. In multivariate analyses adjusting for age, sex, body mass index, smoking habits, alcohol intake, regular exercise, aspirin and analgesics use, family history of colon cancer, education level, fatty liver, high-sensitivity C reactive protein, homeostasis model assessment of insulin resistance, total cholesterol, and triglyceride, an increase in ALT was positively associated with the prevalence of low-risk and high-risk adenoma (P for trend = 0.029 and 0.027, respectively). The highest quartile group of ALT level showed a significantly increased prevalence in low-risk (odds ratio, 1.17) and high-risk adenoma (odds ratio, 1.48) groups compared with the lowest quartile group. This phenomenon persisted in the subgroup analysis in men, but not in women.

CONCLUSIONS

In the asymptomatic healthy population, high serum ALT is significantly associated with the risk of CRA.

Association of serum albumin and aspartate transaminase with 5-year all-cause mortality in HIV/hepatitis C virus coinfection and HIV monoinfection

OBJECTIVE

Liver disease markers have been associated with mortality in HIV-infected individuals in the modern era of effective antiretroviral therapy. Our objective was to determine which markers are most predictive of mortality in HIV-monoinfected and HIV/hepatitis C virus (HCV)-coinfected persons.

RESEARCH DESIGN AND METHODS

We measured serum albumin, total protein, calculated globulin, aspartate transaminase (AST), and alanine transaminase in 193 HIV/HCV-coinfected and 720 HIV-monoinfected persons in the study of Fat Redistribution and Metabolic Change in HIV Infection. We evaluated associations of each marker with 5-year, all-cause mortality, adjusting for cardiovascular, HIV-related factors, inflammation, renal disease, muscle, and adiposity.

RESULTS

After 5 years of follow-up, overall mortality was 21% in HIV/HCV-coinfected and 12% in HIV-monoinfected participants. After multivariable adjustment, lower albumin and higher AST were independently associated with increased mortality. Lower albumin was associated with 49% increased odds of mortality overall [per 0.5 g/dl decrease, 95% confidence interval (CI): 1.2-1.9]; the association was stronger in HIV/HCV-coinfected [odds ratio (OR) = 2.1, 95% CI: 1.4-3.2] vs. HIV-monoinfected (OR = 1.3, 95% CI: 1.0-1.7; HCV-by-albumin interaction: P = 0.038). Higher AST was associated with 41% increased odds of mortality (per AST doubling; 95% CI: 1.1-1.8); associations were much stronger among HIV/HCV-coinfected (OR = 2.5, 95% CI: 1.5-4.1) than HIV-monoinfected (OR = 1.1, 95% CI: 0.8-1.5; HCV-by-AST interaction: P = 0.0042).

CONCLUSION

Lower serum albumin and higher AST appear to be important mortality risk factors in HIV/HCV-coinfection, but much less so in HIV-monoinfected individuals. The association of low albumin with mortality may reflect its role as a negative acute phase response protein. AST levels do not appear to be useful in predicting mortality in HIV-monoinfection and should be considered primarily in the context of HCV-coinfection.

Metabolite Signatures of Metabolic Risk Factors and their Longitudinal Changes

CONTEXT

Metabolic dysregulation underlies key metabolic risk factors—obesity, dyslipidemia, and dysglycemia.

OBJECTIVE

To uncover mechanistic links between metabolomic dysregulation and metabolic risk by testing metabolite associations with risk factors cross-sectionally and with risk factor changes over time.

DESIGN

Cross-sectional—discovery samples (n = 650; age, 36–69 years) from the Framingham Heart Study (FHS) and replication samples (n = 670; age, 61–76 years) from the BioImage Study, both following a factorial design sampled from high vs low strata of body mass index, lipids, and glucose. Longitudinal—FHS participants (n = 554) with 5–7 years of follow-up for risk factor changes.

SETTING

Observational studies.

PARTICIPANTS

Cross-sectional samples with or without obesity, dysglycemia, and dyslipidemia, excluding prevalent cardiovascular disease and diabetes or dyslipidemia treatment. Age- and sex-matched by group.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

Gas chromatography-mass spectrometry detected 119 plasma metabolites. Cross-sectional associations with obesity, dyslipidemia, and dysglycemia were tested in discovery, with external replication of 37 metabolites. Single- and multi-metabolite markers were tested for association with longitudinal changes in risk factors.

RESULTS

Cross-sectional metabolite associations were identified with obesity (n = 26), dyslipidemia (n = 21), and dysglycemia (n = 11) in discovery. Glutamic acid, lactic acid, and sitosterol associated with all three risk factors in meta-analysis (P < 4.5 × 10−4). Metabolites associated with longitudinal risk factor changes were enriched for bioactive lipids. Multi-metabolite panels explained 2.5–15.3% of longitudinal changes in metabolic traits.

CONCLUSIONS

Cross-sectional results implicated dysregulated glutamate cycling and amino acid metabolism in metabolic risk. Certain bioactive lipids were associated with risk factors cross-sectionally and over time, suggesting their upstream role in risk factor progression. Functional studies are needed to validate findings and facilitate translation into treatments or preventive measures.

Impact of elevated aspartate and alanine aminotransferase on metabolic syndrome and its components among adult people living in Ningxia, China

OBJECTIVE

Metabolic syndrome (MS) is a combination of medical disorders that increase the risk for cardiovascular disease and diabetes mellitus. It suggests an association between an elevated serum aminotransferase level and MS. Little data show the relationship between the levels of serum aminotransferase and the incidence of MS in Ningxia, China.

METHODS

A total of 5415 subjects who received medical health checkups from 2007 to 2009 were enrolled in the study. The participants were interviewed by trained health workers under a structured questionnaire. MS was defined according to the modified ATPIII criteria for Asian Americans by the American Heart Association (AHA-ATP III).

RESULTS

The prevalence of elevated aspartate aminotransferase (AST) and ALT (>40 U/L) were 7.1% and 22.2% in males, and 2.1% and 4.8% in females respectively. The prevalence of MS was 32.1% in males and 15.4% in females. The components of MS were significantly more in the group with elevated aminotransferase levels than in the group with normal aminotransferase levels. The odds ratios (95% CI) for elevated AST were 1.90 (1.49, 2.42), 2.59 (2.01, 3.39), 1.68 (1.32, 2.15), and 1.81 (1.36, 2.42) in the adults with abdominal obesity, high serum triglycerides levels, high blood pressure, and high plasma glucose levels respectively. After adjustment for age, the odds ratios (95% CI) for elevated ALT were 3.08 (2.63, 3.61), 4.30 (3.64, 5.08), 1.26 (1.08, 1.48), 2.16 (1.93, 2.65) and 2.38 (1.96, 2.87) in adults with abdominal obesity, high serum triglycerides levels, low serum high-density lipoproteincholesterol (HDL-C), high blood pressure, and high plasma glucose levels respectively. The odds ratios (95% CI) for elevated AST were 1.67 (1.06, 2.63), 2.28 (1.46, 3.63), 2.59 (1.59, 4.21) and for elevated ALT 2.02 (1.50, 2.73), 2.68 (1.96, 3.65), 3.94 (2.86, 5.43) for the subjects with 1, 2, and ≥3 risk factors after adjustment for age, gender, and BMI.

CONCLUSION

The serum aminotransferase levels were higher in males compared to females, and serum ALT level was more closely associated with MS than the AST level in adults in Ningxia, China. With an increasing the number of components of MS, the aminotransferase levels and the risks for elevated aminotransferase increase, whereas the AST/ALT ratios decrease.

γ-glutamyl transpeptidase in men and alanine aminotransferase in women are the most suitable parameters among liver function tests for the prediction of metabolic syndrome in nonviral hepatitis and nonfatty liver in the elderly

BACKGROUND/AIMS

Nonalchoholic fatty liver disease (NAFLD) has been reported as a hepatic manifestation of metabolic syndrome (MetS); it is common and accounts for 80% of the cases with abnormal liver function tests (LFTs). In addition, several studies have proved that there is a correlation between abnormal LFTs and MetS. Therefore, LFTs may represent the abnormal metabolic status of livers in the patients with MetS. To identify the early state of metabolic dysfunction, we investigate the value of LFTs for the future MetS development in the relatively healthy (non-NAFLD) elderly.

PATIENTS AND METHODS

A total of 16,912 subjects met the criteria for analysis. In the first stage of this study, subjects were enrolled in the cross-sectional study in order to find out the optimal cutoff value in different LFTs with higher chances to have MetS. In the second stage of the present study, subjects with MetS at baseline were excluded from the same study group, and a median 5.6-year longitudinal study was conducted on the rest of the group.

RESULTS

Among all LFTs, only aspartate aminotransferase in both genders and the α-fetal protein in women failed to show the significance in distinguishing subjects with MetS by the receiver operating characteristic curve. In the Kaplan-Meier plot, only γ-glutamyl transpeptidase (γ-GT) in men and the alanine aminotransferase (ALT) in women could be used to successfully separate subjects with higher risk of developing the MetS from those with lower risk. Finally, in the multivariant Cox regression model, similar results were identified. Still, the hazard ratio (HR) to have future MetS, γ-GT in men, and ALT in women showed significance (HR = 1.511 in men and 1.504 in women).

CONCLUSION

Among all the different LFTs, γ-GT (>16 U/L) in male and ALT (>21 U/L) in female were the best predictors for the development of MetS in healthy elderly. These two liver markers could be an ancillary test in predicting future MetS development/diagnosis. Elevation of the LFTs without underlying liver diseases should be treated as a warning sign of the possible MetS development in the elderly.

Alanine aminotransferase within reference range is associated with metabolic syndrome in middle-aged and elderly Chinese men and women

OBJECTIVE

To investigate the association between serum ALT level within reference range (≤40 U/L) and morbidity of MetS in a large middle-aged and elderly Chinese community population.

METHODS

Our study was a community-based cross-sectional survey which used cluster sampling method. From November 2011 to August 2012 a total of 16,539 subjects (males 5184; females 11,355) with serum ALT levels in the normal range aged ≥40 years from Shijingshan District (Beijing, China) were included in the study. Data on demographic information, lifestyle, history of diabetes mellitus, hypertension, dyslipidemia and liver disease were collected. Body height, body weight, waist circumference, hip circumference, and blood pressure were recorded. The oral glucose tolerance test or a standard meal test and blood lipid test was performed. The determination of metabolic syndrome was according to the unified criteria published in 2009. The association between serum ALT level and metabolic syndrome was evaluated by logistic regression. The association between serum ALT level and all components of metabolic syndrome was evaluated by multiple linear regression. p < 0.05 was regarded as statistically significant.

RESULTS

The prevalence of metabolic syndrome was 41.4% in males and 40.6% in females. We found ALT level was positively associated with odds of metabolic syndrome after adjustment for age, smoking, and alcohol intake. The odds ratio values of MetS in the ALT quartiles 2-4 groups were 1.920 (95%CI: 1.619-2.277), 2.853 (95%CI: 2.407-3.381), and 4.171 (95%CI: 3.510-4.956) in males; 1.889 (95%CI: 1.671-2.136), 3.490 (95%CI: 3.095-3.935), and 5.593 (95%CI: 4.957-6.311) in females, respectively, compared with the ALT quartile 1 group.

CONCLUSIONS

Higher serum ALT level within the reference range was associated with increased odds of MetS in middle-aged and elderly Chinese men and women.

Modifiable clinical and lifestyle factors are associated with elevated alanine aminotransferase levels in newly diagnosed type 2 diabetes patients: results from the nationwide DD2 study

BACKGROUND

Current literature lacks data on markers of non-alcoholic fatty liver disease (NAFLD) in newly diagnosed type 2 diabetes mellitus (T2DM) patients. We therefore, conducted a cross-sectional study to examine modifiable clinical and lifestyle factors associated with elevated alanine aminotransferase (ALT) levels as a marker of NAFLD in new T2DM patients.

METHODS

Alanine aminotransferase levels were measured in 1026 incident T2DM patients enrolled in the nationwide Danish Centre for Strategic Research in Type 2 Diabetes (DD2) cohort. We examined prevalence of elevated ALT (>38 IU/L for women and >50 IU/L for men) and calculated prevalence ratios associated with clinical and lifestyle factors using Poisson regression. We examined the association with other biomarkers by linear regression.

RESULTS

The median value of ALT was 24 IU/L (interquartile range: 18-32 IU/L) in women and 30 IU/L (interquartile range: 22-41 IU/L) in men. Elevated ALT was found in 16% of incident T2DM patients. The risk of elevated ALT was increased in patients who were <40 years old at diabetes debut [adjusted prevalence ratio (aPR): 1.96, 95% confidence interval (CI): 1.15-3.33], in those with alcohol overuse (>14/>21 drinks per week for women/men) (aPR: 1.60, 95% CI: 1.03-2.50), and in those with no regular physical activity (aPR: 1.42, 95% CI: 1.04-1.93). Obesity and metabolic syndrome per se showed no association with elevated ALT when adjusted for other markers, whereas we found positive associations of ALT with increased C-peptide (β = 0.14, 95% CI: 0.06-0.21) and fasting blood glucose (β = 0.07, 95% CI: 0.03-0.11).

CONCLUSIONS

Among newly diagnosed T2DM patients, several modifiable clinical and lifestyle factors are independent markers of elevated ALT levels.

Alanine aminotransferase and risk of the metabolic syndrome: a linear dose-response relationship

BACKGROUND

Elevated baseline circulating alanine aminotransferase (ALT) level has been demonstrated to be associated with an increased risk of the metabolic syndrome (MetS), but the nature of the dose-response relationship is uncertain.

METHODS

We performed a systematic review and meta-analysis of published prospective cohort studies to characterize in detail the nature of the dose-response relationship between baseline ALT level and risk of incident MetS in the general population. Relevant studies were identified in a literature search of MEDLINE, EMBASE, and Web of Science up to December 2013. Prospective studies in which investigators reported relative risks (RRs) of MetS for 3 or more categories of ALT levels were eligible. A potential nonlinear relationship between ALT levels and MetS was examined using restricted cubic splines.

RESULTS

Of the 489 studies reviewed, relevant data were available on 29,815 non-overlapping participants comprising 2,125 incident MetS events from five prospective cohort studies. There was evidence of a linear association (P for nonlinearity=0.38) between ALT level and risk of MetS, characterised by a graded increase in MetS risk at ALT levels 6-40 U/L. The risk of MetS increased by 14% for every 5 U/L increment in circulating ALT level (95% CI: 12-17%). Evidence was lacking of heterogeneity and publication bias among the contributing studies.

CONCLUSIONS

Baseline ALT level is associated with risk of the MetS in a linear dose-response manner. Studies are needed to determine whether the association represents a causal relationship.

Elevated alanine aminotransferase is strongly associated with incident metabolic syndrome: a meta-analysis of prospective studies

BACKGROUND

The incidence of metabolic syndrome (MetS) is rapidly increasing worldwide and associated with alanine aminotransferase (ALT) activity. However, the impact of ALT activity on MetS incidence is inconsistent in published literature. We therefore estimated the association between elevated ALT activity and incident MetS through a meta-analysis of prospective cohort studies.

METHODS/PRINCIPAL FINDINGS

All published prospective cohort studies on the association between elevated ALT activity and incident MetS were retrieved from Pubmed, Embase, and the Institute for Scientific Information (ISI). In all, seven prospective cohort studies, with 31545 participants and 2873 cases of incident MetS were recruited. If there was insignificant heterogeneity (P-value>0.05 and I(2)<50%), the fixed-effect model was used to calculate the pooled relative risks (RRs) of incident MetS induced by raised ALT. Otherwise, the random-effect model was used. The calculated RR was 1.81 (95% confidence interval [CI]: 1.49-2.14) when the incidence of MetS was compared between the highest versus the lowest classification of ALT activities. The pooled RR was 1.13 (95% CI: 1.11-1.16) in dose-response analysis with 5 units per liter (U/l) of ALT increment. Subgroup analysis suggested that gender disparity might be the main origin of heterogeneity in overall analysis (P = 0.007 between RRs of gender-specific subgroups evaluated with 5 U/l increments of ALT). Women had a higher dose-response risk of MetS incidence (1.38, 95% CI: 1.20-1.55) than men. Furthermore, sensitivity analysis confirmed the stability of results. No publication bias was found in our meta-analysis.

CONCLUSIONS/SIGNIFICANCE

Current evidence from prospective studies supports the association between ALT elevation and increasing MetS incidence. This association is closer and more consistent in female population. Further studies are needed to confirm this association and to investigate the potential mechanism of ALT activity on MetS occurrence.

Upper limit of normal for alanine aminotransferase: quo vadis?

Several studies suggest that a substantial number of patients with normal serum alanine aminotransferase (ALT) levels, defined by current thresholds, have ongoing hepatic necro-inflammation and fibrosis, and are at risk of liver disease progression. A major problem lies in the definition of normality. The current upper limit of normal (ULN) for ALT was established in the 1980s when reference populations were likely to include many persons with hepatitis C virus infection and nonalcoholic fatty liver disease. Because ALT may be influenced, not only by liver disease, but also by other medical conditions, changing lifestyle factors and demographic determinants, the current ALT ULN threshold has recently been challenged. This review not only highlights current evidence on why and how ALT ULN should be redefined, but also discusses the current concerns about updating the ULN threshold for ALT.

Alanine aminotransferase is associated with an adverse nocturnal blood glucose profile in individuals with normal glucose regulation

OBJECTIVE

Although the association between alanine aminotransferase (ALT) levels and risk of type 2 diabetes is well-studied, the effects of slightly increased ALT levels within the normal range on the temporal normal glucose profile remains poorly understood.

METHODS

A total of 322 Chinese subjects without impaired glucose tolerance or previous diagnoses of diabetes were recruited for study from 10 hospitals in urban areas across China. All subjects wore a continuous glucose monitoring (CGM) system for three consecutive days. The diurnal (06∶00-20∶00) and nocturnal (20∶00-06∶00) mean blood glucose (MBG) levels were calculated. Subjects were stratified by ALT quartile level and correlation analyses were performed.

RESULTS

The median ALT level was 17 IU/L, and subjects with ALT ≥17 IU/L had higher nocturnal MBG level than those with ALT <17 IU/L (P<0.05). Nocturnal MBG was positively correlated with ALT levels (Pearson correlation analysis: r = 0.187, P = 0.001), and the correlation remained significant after correction for the homeostatic model assessment of insulin resistance index (HOMA-IR) (r = 0.105, P = 0.041). No correlations were found between diurnal MBG and ALT, and nocturnal or diurnal MBG and aspartate aminotransferase or gamma-glutamyltransferase (all, P>0.05). Multivariate stepwise regression analysis of elevated nocturnal MBG identified increased HOMA-IR, elevated ALT levels, and decreased homeostatic model assessment of ß-cell function as independent factors (all, P<0.05).

CONCLUSIONS

Mildly elevated ALT levels, within the normal range, are associated with unfavorable nocturnal glucose profiles in Chinese subjects with normal glucose regulation.

Cardiovascular disease is associated with high-fat-diet-induced liver damage and up-regulation of the hepatic expression of hypoxia-inducible factor 1α in a rat model

CVD (cardiovascular disease) is associated with abnormal liver enzymes, and NAFLD (non-alcoholic fatty liver disease) is independently associated with cardiovascular risk. To gain insights into the molecular events underlying the association between liver enzymes and CVD, we developed an HFD (high-fat diet)-induced NAFLD in the SHR (spontaneously hypertensive rat) and its control WKY (Wistar-Kyoto) rat strain. We hypothesized that hepatic induction of Hif1a (hypoxia-inducible factor 1α) might be the link between CVD and liver injury. Male SHRs (n=13) and WKY rats (n=14) at 16 weeks of age were divided into two experimental groups: standard chow diet and HFD (10 weeks). HFD-fed rats, irrespective of the strain, developed NAFLD; however, only HFD-SHRs had focus of lobular inflammation and high levels of hepatic TNFα (tumour necrosis factor α). SHRs had significantly higher liver weight and ALT (alanine aminotransferase) levels, irrespective of NAFLD. Liver abundance of Hif1a mRNA and Hif1α protein were overexpressed in SHRs (P<0.04) and were significantly correlated with ALT levels (R=0.50, P<0.006). This effect was not reverted by a direct acting splanchnic vasodilator (hydralazine). Angiogenesis may be induced by the HFD, but the disease model showed significantly higher hepatic Vegf (vascular endothelial growth factor) levels (P<0.025) even in absence of dietary insult. Hif1a mRNA overexpression was not observed in other tissues. Liver mRNA of Nr1d1 (nuclear receptor subfamily 1, group D, member 1; P<0.04), Ppara [Ppar (peroxisome-proliferator-activated receptor) α; P<0.05], Pparg (Pparγ; P<0.001) and Sirt1 (Sirtuin 1; P<0.001) were significantly upregulated in SHRs, irrespective of NAFLD. Sirt1 and Hif1a mRNAs were significantly correlated (R=0.71, P<0.00002). In conclusion, CVD is associated with Hif1a-related liver damage, hepatomegaly and reprogramming of liver metabolism, probably to compensate metabolic demands.

Alanine and aspartate aminotransferase and glutamine-cycling pathway: Their roles in pathogenesis of metabolic syndrome

Although new research technologies are constantly used to look either for genes or biomarkers in the prediction of metabolic syndrome (MS), the pathogenesis and pathophysiology of this complex disease remains a major challenge. Interestingly, Cheng et al recently investigated possible pathways underlying MS by high-throughput metabolite profiling in two large and well characterized community-based cohorts. The authors explored by liquid chromatography and mass spectrometry the plasma concentrations of 45 distinct metabolites and examined their relation to cardiometabolic risk, and observed that metabolic risk factors such as obesity, insulin resistance (IR), high blood pressure, and dyslipidemia were associated with several metabolites, including branched-chain amino acids, other hydrophobic amino acids, tryptophan breakdown products, and nucleotide metabolites. In addition, the authors found a significant association of IR traits with glutamine, glutamate and the glutamine-to-glutamate ratio. These data provide new insight into the pathogenesis of MS-associated phenotypes and introduce a crucial role of glutamine-cycling pathway as prominently involved in the development of metabolic risk. We consider that the hypothesis about the role of abnormal glutamate metabolism in the pathogenesis of the MS is certainly challenging and suggests the critical role of the liver in the global metabolic modulation as glutamate metabolism is linked with aminotransferase reactions. We discuss here the critical role of the “liver metabolism” in the pathogenesis of the MS and IR, and postulate that before fatty liver develops, abnormal levels of liver enzymes, such as alanine and aspartate aminotransferases might reflect high levels of hepatic transamination of amino acids in the liver.

Non-alcoholic fatty liver disease across the spectrum of hypothyroidism

BACKGROUND & AIMS

The aim of this study was to characterize the relationship between the broad spectrum of hypothyroidism and NAFLD.

METHODS

A cross-sectional study with 4648 health check-up subjects (2324 cases with hypothyroidism vs. age- and sex-matched controls) was conducted. The subjects were categorized as having either subclinical [thyroid-stimulating hormone (TSH) ≥4.1 mIU/L and normal free thyroixine (T(4)) level (0.7-1.8 ng/dl)] or overt hypothyroidism [free T(4)<0.7 ng/dl]. NAFLD was diagnosed on the basis of typical ultrasonographic findings, and alcohol consumption of less than 20 g/day in the absence of other causes of liver disease.

RESULTS

The mean age of the subjects was 48.6±11.8 years and 62.4% were female. NAFLD was significantly associated with hypothyroidism (30.2% patients vs. 19.5% control, p<0.001). The prevalence of NAFLD and abnormal liver enzyme levels (ALT>33/25 IU/L) increased steadily with increasing grades of hypothyroidism (for NAFLD, subclinical: 29.9% and overt: 36.3%; for abnormal ALT, 20.1% and 25.9%, p<0.001, respectively). Multivariate regression analysis showed that NAFLD was statistically significantly associated with hypothyroidism (odds ratio (OR) 1.38, 95% confidence interval (CI), 1.17-1.62) and the grade of hypothyroidism in a dose-dependent manner (OR 1.36, 95% CI, 1.16-1.61 in subclinical hypothyroidism and OR 1.71, 95% CI, 1.10-2.66 in overt hypothyroidism).

CONCLUSIONS

Subclinical hypothyroidism, even in the range of upper normal TSH levels, was found to be related to NAFLD in a dose-dependent manner. Hypothyroidism is closely associated with NAFLD independently of known metabolic risk factors, confirming a relevant clinical relationship between these two diseases.

Cardiomyocyte triglyceride accumulation and reduced ventricular function in mice with obesity reflect increased long chain Fatty Acid uptake and de novo Fatty Acid synthesis

A nonarteriosclerotic cardiomyopathy is increasingly seen in obese patients. Seeking a rodent model, we studied cardiac histology, function, cardiomyocyte fatty acid uptake, and transporter gene expression in male C57BL/6J control mice and three obesity groups: similar mice fed a high-fat diet (HFD) and db/db and ob/ob mice. At sacrifice, all obesity groups had increased body and heart weights and fatty livers. By echocardiography, ejection fraction (EF) and fractional shortening (FS) of left ventricular diameter during systole were significantly reduced. The V(max) for saturable fatty acid uptake was increased and significantly correlated with cardiac triglycerides and insulin concentrations. V(max) also correlated with expression of genes for the cardiac fatty acid transporters Cd36 and Slc27a1. Genes for de novo fatty acid synthesis (Fasn, Scd1) were also upregulated. Ten oxidative phosphorylation pathway genes were downregulated, suggesting that a decrease in cardiomyocyte ATP synthesis might explain the decreased contractile function in obese hearts.

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.

Cognitive-behavioral treatment of nonalcoholic Fatty liver disease: a propensity score-adjusted observational study

The effectiveness of cognitive-behavior treatment (CBT) in nonalcoholic fatty liver disease (NAFLD), largely related to overweight/obesity and considered the hepatic expression of the metabolic syndrome (MS), has so far been tested in very limited samples. In a tertiary referral center, consecutively observed NAFLD subjects were offered a CBT program aimed at weight loss and increased physical activity, based on 13 group sessions; 68 cases entered the treatment protocol, those who refused (n = 82) were given recommendations for diet and physical activity. Treatment goals (weight loss ≥7% initial body weight, normalization of liver enzymes, and improved parameters of MS) were tested by logistic regression at 6 months (all cases) and at 2 years, both on intention-to-treat and in completers (Diet, 78; CBT, 65). The results were adjusted for the propensity score of attending the CBT program, based on civil, anthropometric and clinical variables. At baseline the CBT group had a larger prevalence of obesity and more severe insulin resistance (homeostasis model assessment (HOMA)). At follow-up, CBT was associated with a higher probability of weight loss and normal liver enzymes (6-month: odds ratio (OR), 2.56; 95% confidence interval (CI), 1.15-5.69; 2-year intention-to-treat: OR, 3.57, 95% CI, 1.59-8.00), after adjustment for propensity and changes in body weight. A similar trend was observed in the outcome goals of insulin resistance and the score of MS, which were both reduced. In conclusion, subjects with NAFLD participating in a CBT program significantly improve their general and liver parameters. The beneficial effects are largely maintained at 2-year follow-up, in keeping with the lifestyle-related pathogenesis of disease.

Alanine aminotransferase is associated with metabolic syndrome independently of insulin resistance

BACKGROUND

Few studies have examined the effect of insulin resistance on the association between alanine aminotransferase (ALT) and metabolic syndrome. The association between ALT levels and metabolic syndrome were determined, independently of insulin resistance in Korean populations.

METHODS AND RESULTS

The association between ALT and metabolic syndrome were examined in 28,456 subjects who visited 7 Health Promotion Centers at University Hospitals in Korea from 2006 to 2008. HOMA-IR index was used to represent insulin resistance index. ALT levels were found to be positively associated with metabolic syndrome after adjusting for age, alcohol intake, and smoking status. Furthermore, when additional adjustment was made for insulin resistance, this association between ALT and metabolic syndrome, although slightly attenuated, remained strongly significant. Subjects in the highest ALT quartile were found to have a higher risk of having metabolic syndrome than those in the lowest quartile (odds ratio (OR)=4.45, 95% confidence interval (CI)=3.96-4.99 for men and OR=3.51, 95%CI=2.73-4.52 for women). In addition, the association between ALT level and the risk of metabolic syndrome was significantly higher in the relatively low risk group.

CONCLUSIONS

ALT levels were found to be significantly associated with metabolic syndrome independently of insulin resistance and with an interaction by age. Further cohort studies are needed to determine the usefulness of ALT levels for predicting the risk of metabolic syndrome.

Heart disease and stroke statistics--2011 update: a report from the American Heart Association

Each year, the American Heart Association (AHA), in conjunction with the Centers for Disease Control and Prevention, the National Institutes of Health, and other government agencies, brings together the most up-to-date statistics on heart disease, stroke, other vascular diseases, and their risk factors and presents them in its Heart Disease and Stroke Statistical Update. The Statistical Update is a valuable resource for researchers, clinicians, healthcare policy makers, media professionals, the lay public, and many others who seek the best national data available on disease morbidity and mortality and the risks, quality of care, medical procedures and operations, and costs associated with the management of these diseases in a single document. Indeed, since 1999, the Statistical Update has been cited more than 8700 times in the literature (including citations of all annual versions). In 2009 alone, the various Statistical Updates were cited ≈1600 times (data from ISI Web of Science). In recent years, the Statistical Update has undergone some major changes with the addition of new chapters and major updates across multiple areas. For this year’s edition, the Statistics Committee, which produces the document for the AHA, updated all of the current chapters with the most recent nationally representative data and inclusion of relevant articles from the literature over the past year and added a new chapter detailing how family history and genetics play a role in cardiovascular disease (CVD) risk. Also, the 2011 Statistical Update is a major source for monitoring both cardiovascular health and disease in the population, with a focus on progress toward achievement of the AHA’s 2020 Impact Goals. Below are a few highlights from this year’s Update.

Positive correlations of liver enzymes with metabolic syndrome including insulin resistance in newly diagnosed type 2 diabetes mellitus

It has long been proposed that elevation of liver enzymes including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and γ-glutamyltransferase (GGT) may be associated with insulin resistance (IR). In the present study, we aimed to investigate the association of the above mentioned liver enzymes with IR by using hyperinsulinemic euglycemic clamp, as well as their relationship with individual component of metabolic syndrome (MetS) in 95 newly diagnosed type 2 diabetes (T2DM) Chinese patients. All the diagnosed patients did not use drugs for treatment of diabetes or dyslipidemia previously and were divided into IR and non-IR groups. The results showed that IR group had significantly higher ALT, AST, and GGT (P<0.01, P<0.01, and P<0.05, respectively) compared with non-IR group. According to the individual MetS component, ALT and AST were significantly increased in patients with high blood pressure compared with those without (both P<0.001); ALT and GGT were increased in patients with high triglyceride (P<0.05 and P<0.01); AST was increased in patients with central obesity (P<0.05). In correlation analysis, a significant association was found between the three liver enzymes and clamp insulin sensitivity index (all P<0.001). In the linear regression analysis, ALT was the determinant of clamp ISI, independent of age, sex, BMI, and fasting and OGTT 2 h plasma glucose (P<0.0001). In conclusion, liver enzymes, especially ALT, were significantly associated with IR according to direct clamp assessment, which were independent of the traditional risk factors in diabetic patients; and individual liver enzymes may have different relationship with individual component of MetS.

Shift work aggravates metabolic syndrome development among early-middle-aged males with elevated ALT

AIM: To examine whether shift work accelerates metabolic syndrome (MetS) development among early middle-aged males with elevated alanine aminotransferase (e-ALT).

METHODS: A retrospective, observational follow-up study on MetS development at a 5-year interval was conducted using health examination data. Nine hundred and ninety six male employees not fulfilling MetS criteria at screening were enrolled. Age, MetS-components, liver enzymes, serological markers for viral hepatitis, abdominal ultrasound, insulin resistance status, lifestyles, and workplace factors were analyzed.

RESULTS: The prevalence of elevated serum ALT (> 40 U/L, e-ALT) at baseline was 19.1%. There were 381 (38.3%) workers with long-term exposures to day-night rotating shift work (RSW). 14.2% of subjects developed MetS during follow-up. After 5 years, the workers with e-ALT had significantly unfavorable changes in MetS-components, and higher rates of MetS development, vs subjects with normal baseline ALT levels. Workers with both baseline e-ALT and 5-year persistent RSW (pRSW) exposure had the highest rate of MetS development. Also, e-ALT-plus-pRSW workers had a significant increase in MetS-components at follow-up, compared with the other subgroups. After controlling for potential confounders, e-ALT-plus-pRSW workers posed a significant risk for MetS development (odds ratio, 2.7; 95% confidence interval, 1.4-5.3, vs workers without baseline e-ALT nor pRSW).

CONCLUSION: We suggest that all early middle-aged male employees with e-ALT should be evaluated and managed for MetS. Particularly in terms of job arrangements, impacts of long-term RSW on MetS development should be assessed for all male employees having baseline e-ALT.

The association between normal alanine aminotransferase levels and the metabolic syndrome: 2005 Korean National Health and Nutrition Examination Survey

The metabolic syndrome is known to sometimes exist in the presence of normal aminotransferase levels. The purpose of this study was to determine the lowest sex-specific level of alanine aminotransferase associated with the metabolic syndrome in a nationwide, representative Korean population. We analyzed data from adults 20 years and older (n = 3405) assessed in the Third Korean National Health and Nutrition Examination Survey (2005). Participants were divided into 4 groups according to the quartiles of alanine aminotransferase levels for each sex. Logistic regression modeling was performed after adjustment for age, body mass index, waist circumference, smoking, ingested alcohol amount, and physical activity. Alanine aminotransferase level groups 3 and 4 in women (> or =15 IU/L) and group 4 in men (> or =27 IU/L) were significantly associated with the metabolic syndrome compared with the lowest alanine aminotransferase groups (<16 IU/L in men, <11 IU/L in women). In men, the odds ratio (95% confidence interval) of the metabolic syndrome was 2.71 (1.31-5.63) for alanine aminotransferase group 4 (> or =27 IU/L). In women, odds ratios were 1.69 (1.02-2.80) and 2.06 (1.23-3.43) for alanine aminotransferase groups 3 (15 < or = alanine aminotransferase < 19 IU/L) and 4 (> or =19 IU/L), respectively. High-normal alanine aminotransferase levels (> or =27 IU/L in men, > or =15 IU/L in women) were strongly associated with the metabolic syndrome in Korean adults.

High prevalence of coronary heart disease in type 2 diabetic patients with non-alcoholic fatty liver disease

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) is closely associated with insulin resistance and metabolic syndrome. Prevalence of NAFLD increases greatly in patients with type 2 diabetes mellitus (T2DM), and it may also increase cardiovascular disease mortality and morbidity. The aim of our study was to investigate the prevalence of NAFLD in T2DM population and to compare the prevalence of coronary heart disease (CHD) and its risk factors between diabetic patients with and without NAFLD in a Chinese population.

METHODS

A cross-sectional survey was conducted among 560 cases of in-patient T2DM patients from January 2002 to January 2009 in southern China. Patients were divided into two groups (NAFLD and non-NAFLD) and underwent clinical examination, anthropometry, laboratory tests and routine liver ultrasonography.

RESULTS

Prevalence of NAFLD was 75.18% (421 cases) among all participants, and 285 cases (67.70%) had normal liver function and no symptoms. NAFLD group had higher body mass index (BMI), waist/hip circumference ratio (WHR), alanine aminotransferase (ALT), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels than those without NAFLD (p<0.01). Moreover, the prevalence of CHD was also higher in the NAFLD group (p<0.01), especially in those male patients with elevated plasma ALT.

CONCLUSIONS

NAFLD is a common condition among T2DM patients. Its occurrence may be related to sex, age, abdominal obesity, dyslipidemia metabolism, etc. and it is associated with a higher prevalence of CHD. Plasma ALT levels may act as a marker.

Impact of metabolic syndrome on elevated serum alanine aminotransferase levels in the Japanese population

Measurement of the serum alanine aminotransferase (ALT) level is used as an initial test for detection of liver diseases, and recent studies have also highlighted its potential value as a measure of overall health and survival as a marker of an increased risk of metabolic disorder. This study was designed to clarify the prevalence of elevated ALT levels in the Japanese population and to assess factors associated with ALT elevation. The subjects were 2165 individuals aged 40 to 85 years who participated in a Japanese community-based study referred to as the Takahata Study. Serum ALT levels and factors associated with ALT elevation were investigated. Among 2087 subjects who were negative for hepatitis B and C, the rates of elevated ALT greater than 30 U/L in men and greater than 25 U/L in women were 217 (22.7%) of 957 and 239 (21.2%) of 1130, respectively. These ALT cutoff levels had a specificity of more than 80% for exclusion of subjects with none or 1 of 3 metabolic risk factors: hypertension, lipid metabolism abnormality, and hyperglycemia. Multivariate analysis revealed 5 factors with a significant association with ALT elevation in men (n = 957): high gamma-glutamyltranspeptidase, low adiponectin, high low-density lipoprotein cholesterol, high body mass index, and high homeostasis model assessment insulin resistance index. Similarly, 4 factors were significantly associated with ALT elevation in women (n = 1130): high gamma-glutamyltranspeptidase, low adiponectin, high body mass index, and high homeostasis model assessment insulin resistance index. These results suggest that elevated ALT levels in the Japanese population older than 40 years have a strong association with metabolic syndrome-related features including obesity and insulin resistance.

Adherence to the Mediterranean diet moderates the association of aminotransferases with the prevalence of the metabolic syndrome; the ATTICA study

Background

Elevated liver enzymes are markers of liver steatosis and metabolic syndrome. We aimed to investigate the association of Mediterranean diet on the relationship between aminotransferases (i.e., AST, ALT, gGT) and the metabolic syndrome.

Methods

The ATTICA study has randomly enrolled 1514 adult males (18–87 yrs) and 1528 females (18–89 yrs) from the greater area of Athens. Adherence to Mediterranean diet was assessed through the MedDietScore. According to NCEP III criteria, participants were classified into those with or without the metabolic syndrome.

Results

Women with metabolic syndrome had higher γGT (p = 0.02) and lower AST/ALT levels (p = 0.018) than those without, and men with metabolic had a lower AST/ALT ratio (p = 0.01) compared to those without metabolic syndrome. The AST/ALT ratio was also positively correlated with MedDietScore (rho = 0.17, p < 0.001), while higher MedDietScore was associated with lower likelihood of having the metabolic syndrome in a multi-adjusted analysis (OR = 0.34, 95% CI: 0.16–0.73). Stratified analysis by the level of adherence to the Mediterranean diet, revealed that only in subjects away or with moderate adherence to the Mediterranean diet, an increase in the AST/ALT ratio was associated with lower likelihood of having the metabolic syndrome (OR = 0.33, p < 0.05 and OR = 0.34, p < 0.09, respectively); however, when we focused in those with greater adherence to the Mediterranean diet, AST/ALT ratio was not associated with the presence of the syndrome (OR = 0.51, p = 0.55). These findings remained similar in both genders, and even when the quantity of alcohol drinking was taken into account.

Conclusion

Aminotransferases ratio constitutes a marker of the metabolic syndrome among healthy adults; however, this relationship is moderated when individuals are close to the Mediterranean dietary pattern.

Relationship between alanine aminotransferase levels and metabolic syndrome in nonalcoholic fatty liver disease

OBJECTIVE

To investigate the relationship between alanine aminotransferase (ALT) levels and metabolic syndrome (MS) in nonalcoholic fatty liver disease (NAFLD).

METHODS

A total of 26527 subjects who received medical health checkup in our hospital from January 2005 to July 2007 were enrolled in the study. The diagnosis of fatty liver was based on ultrasound imaging. MS was defined according to the criteria of the Adult Treatment Panel III. ALT, triglyceride (TG), high density lipoprotein cholesterol (HDL-c), fasting plasma glucose (FPG), height, weight, waist circumference (WC), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured in each subject to analyze the relationship between MS and ALT activity.

RESULTS

(1) The prevalence of NAFLD in men (30.94%) was significantly higher than that in women (15.65%); (2) The incidence of MS in NAFLD (33.83%) was significantly greater than that in non-NAFLD (10.62%); (3) Of the 6470 subjects with NAFLD, in the age-adjusted partial correlation analysis, there were statistically significant correlations between the ALT levels and most metabolic risk factors in each sex (P<0.01), except that ALT levels had no correlation with HDL-c in women. Moreover, in the multiple stepwise regression analysis, SBP lost its significance, and WC, body mass index (BMI), age, DBP, TG and FPG were independently associated with ALT levels in both sexes (P<0.05). HDL-c remained significant and was independently related to ALT levels in men; (4) ALT levels were significantly higher in subjects with MS compared to those without MS (P<0.001). Mean ALT levels increased with the number of MS components in each sex (P<0.05 for trend).

CONCLUSION

We found a strong relationship between ALT levels and MS in NAFLD and revealed that the cluster of MS components might be the predictor for ALT elevations.

Aminotransferase levels and 20-year risk of metabolic syndrome, diabetes, and cardiovascular disease

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of obesity and metabolic syndrome (MetS). Alanine aminotransferase (ALT) levels are used to detect NAFLD and have also been associated with increased risk for MetS, diabetes mellitus, and cardiovascular disease (CVD). We studied the relationship between ALT levels and these disorders in a long-term follow-up study.

METHODS

Framingham Offspring Heart Study participants (n = 2812; mean age, 44 years; 56% women) were followed for the development of MetS, diabetes, CVD, and all-cause mortality using logistic regression (MetS, diabetes) or Cox proportional hazards models (CVD, all-cause mortality).

RESULTS

Among individuals at baseline, per 1 standard deviation increase in log ALT level, there were increased odds of the development of MetS (odds ratio [OR] 1.21, P < .001) and diabetes (OR, 1.48; P < .0001) over 20 years of follow-up. These findings also applied to participants with ALT levels within the normal range (MetS OR, 1.17; P = .006; diabetes OR, 1.34; P =.002). There was an increased risk of CVD in age/gender-adjusted models (hazard ratio, 1.23; P < .0001), but this was attenuated in multivariable-adjusted models (hazard ratio 1.05; P = .27); no association was observed for all-cause mortality. Aspartate aminotransferase levels were found to be associated with an increased risk of only diabetes.

CONCLUSIONS

Both normal and increased levels of ALT are associated with long-term development of multiple metabolic disorders. These results indicate the potential for ALT values as biomarkers for the risk of metabolic disease.