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

Risk of metabolic syndrome in participants within the normal range of alanine aminotransferase: A population-based nationwide study

This study aimed to investigate the risk of metabolic syndrome (MS) in participants whose alanine aminotransferase (ALT) levels were within the normal range in the general population. A cross-sectional study was conducted using nationally representative samples from the Korea National Health and Nutrition Examination Survey 2007-2015. A total of 43,402 adults (men, 17,535; women, 25,867) with ALT ≤40 U/L without a history of hepatitis B and C, liver cirrhosis, or liver cancer were analyzed. The risk of MS was evaluated according to the ALT level. The prevalence of MS significantly increased as the ALT levels increased. The proportions of MS in men were 12.6%, 25.2%, and 39.7% in the ALT levels of <15, 15~30, and 30~40 U/L, respectively (p < 0.001), and those of women were 7.2%, 23.3%, and 44.7% in the ALT levels of <10, 10~20, and 20~40 U/L, respectively (p < 0.001). There was an ALT-dependent relationship in the risk of MS in participants with normal ALT level after adjustment for age, alcohol intake, and body mass index. The adjusted odds ratio (aOR) of MS in men was 2.48 (95% confidence interval [CI], 2.16-2.85) in an ALT level of 30~40 U/L compared with that in ALT <15 U/L (p < 0.001), and the aOR of MS in women was 2.67 (95% CI, 2.26-3.15) in an ALT level of 20~40 U/L compared with that in ALT <10 U/L (p < 0.001). Although within the normal range of ALT, the risk of MS increases as the ALT levels increase. The ALT level in the general population without a history of chronic liver disease may be a useful marker to evaluate for MS.

The longitudinal increments of serum alanine aminotransferase increased the incidence risk of metabolic syndrome: A large cohort population in China

BACKGROUND

Although alanine aminotransferase (ALT) is well known to be associated with metabolic syndrome (MetS), prospective data on longitudinal increments in ALT activities and incident cases of MetS are limited. We analyzed the impact of longitudinal increments of ALT on MetS based on a health check-up population in China.

METHODS

A total of 4491 subjects free of MetS who completed at least two annual health examinations during March 2010 to April 2016 were enrolled in this cohort study. The MetS was defined according to the Joint Interim Statement criteria 2009. The RRs of incident MetS were estimated by using the Cox model and the Joint model in R software.

RESULTS

The cumulative incidence of MetS was 18.55% during the 7 years of follow-up. In the Cox model, the estimated RR of developing MetS was 1.751 (95% CI =1.532-2.000) for 1 unit augmented in LNALT-0 level. In the Joint model, the estimated RR of developing MetS was 3.626 (95% CI = 2.721-4.831) for 1 unit augmented in LNALT activity longitudinally.

CONCLUSIONS

The longitudinal increment of individuals' ALT activity over time increased the incidence risk of MetS and the effects generated by longitudinal increments of ALT on MetS was higher than that generated by baseline ALT.

Correlation between normal range of serum alanine aminotransferase level and metabolic syndrome: A community-based study

Serum alanine aminotransferase (ALT) is a biomarker of hepatocyte damage. However, the relationship between normal range of serum ALT level and metabolic syndrome (MetS) has not been completely understood. This study aimed to investigate the correlation between normal range of serum ALT level and MetS.A total of 2453 participants from the Beijing Community Pre-Diabetes study were enrolled. Multiple linear regression analysis was performed to calculate the regression coefficient. Normal serum ALT levels were divided into quartiles. Logistic regression model was used to compare the relative risk of MetS, and the receiver operating characteristic (ROC) curve to calculate the optimal ALT boundary value for predicting MetS.The frequency of MetS increased with the ALT level within the normal range. Compared with the first group, the risk of MetS was greater in the other quartiles of ALT level in males, the difference was significant for the fourth group. For females, the risk of MetS increased with ALT level within the normal range as well, with all differences showing statistical significance. The optimal ALT boundary value of the ROC curve for males and females was 24.5 and 14.5 U/L, respectively.ALT was related to metabolic factors and used as one of the indicators to assess the morbidity risk of metabolic diseases.

Metabolic disturbances of non-alcoholic fatty liver resemble the alterations typical for type 2 diabetes

Non-alcoholic fatty liver (NAFL) is an independent risk factor for the development of type 2 diabetes (T2DM). We examined metabolic perturbations in patients with NAFL, patients with T2DM, and control (CON) subjects with normal intrahepatic lipid (IHL) content.

A two-step (10 mU/m2 /min; 40 mU/m2/min) hyperinsulinemic–euglycemic clamp was performed in 11 NAFL, 13 T2DM, and 11 CON subjects, all matched for BMI, and aerobic fitness. IHL content was measured using proton magnetic resonance spectroscopy. Because of high IHL content variability in T2DM patients, this group was separated into a high IHL content group (IHL ≥ 5.0%, T2DM+NAFL) and a normal IHL content group (IHL < 5.0%, T2DM-non-NAFL) for further analysis.

IHL content was increased in NAFL and T2DM+NAFL subjects (P<0.050 versus CON and T2DM-non-NAFL subjects). Adipose tissue insulin sensitivity index (Adipo-IRi) was higher in NAFL (P<0.050 versus CON and T2DM-non-NAFL subjects) and in T2DM+NAFL subjects (P=0.055 versus CON subjects, P<0.050 versus T2DM-non-NAFL subjects). Suppression of plasma-free fatty acids (P=0.046) was lower in NAFL compared with CON subjects, with intermediate values for T2DM-non-NAFL, and T2DM+NAFL subjects. Suppression of endogenous glucose production (EGP) and insulin-stimulated glucose disposal (ΔRd) was comparable between NAFL, T2DM-non-NAFL, and T2DM+NAFL subjects (all P>0.05), and was lower in comparison with CON subjects (all P<0.01). Metabolic flexibility was lower in T2DM-non-NAFL subjects (P=0.047) and NAFL subjects (P=0.059) compared with CON subjects. Adipo-IRi (r=0.652, P<0.001), hepatic insulin resistance index (HIRi) (r=0.576, P=0.001), and ΔRd (r=−0.653, P<0.001) correlated with IHL content.

Individuals with NAFL suffer from metabolic perturbations to a similar degree as T2DM patients. NAFL is an important feature leading to severe insulin resistance and should be viewed as a serious health threat for the development of T2DM. ClinicalTrials.gov: NCT01317576

Dose-Response Relationship between Alanine Aminotransferase Levels within the Reference Interval and Metabolic Syndrome in Chinese Adults

PURPOSE

Elevation in serum alanine aminotransferase (ALT) levels is a biomarker for metabolic syndrome (MS); however, the relationship has not been fully investigated within the reference interval of ALT levels. Our objective was to explore the relationship between serum ALT levels within the reference interval and MS in Chinese adults.

MATERIALS AND METHODS

This cross-sectional study included 16028 adults, who attended routine health check-ups at Shengli Oilfield Central Hospital from January 2006 to March 2012. The reference interval of serum ALT level was defined as less than 40 U/L. Logistic regression models and restricted cubic spline were used to evaluate the association of ALT with MS.

RESULTS

The prevalence of MS in the total population was 13.7% (6.4% for females and 18.4% for males). Multiple logistic regression showed that ALT levels were positively associated with MS after adjustment for potential confounding factors. The odds ratio of MS in the top quartile was 4.830 [95% confidence interval (CI): 2.980-7.829] in females and 3.168 (95% CI: 2.649-3.790) in males, compared with the ALT levels in the bottom quartile. The restricted cubic spline models revealed a positive non-linear dose-response relationship between ALT levels and the risk of MS in women (p for nonlinearity was 0.0327), but a positive linear dose-response relationship in men (p for nonlinearity was 0.0659).

CONCLUSION

Serum ALT levels within the reference interval are positively associated with MS in a dose-response manner. Elevated ALT levels, even within the reference interval, may reflect early dysmetabolic changes.

Upper Normal Alanine Aminotransferase Range and Insulin Resistance in Korean Adolescents: Korean National Health and Nutrition Examination Survey, 2009-2010

BACKGROUND

Alanine aminotransferase (ALT) has been one of the most useful biomarkers reflecting liver damage. Some studies have proposed that serum ALT levels, even those within the conventional normal range, are associated with metabolic syndrome and fatty liver.

AIMS

We examined the correlation between ALT levels and insulin resistance (IR) and ALT cutoff value for high IR status in Korean adolescents.

METHODS

A total of 886 subjects (461 boys and 425 girls) who participated in the 2009-2010 Korea National Health and Nutrition Examination Survey were included in this study. Multivariable adjusted logistic regression analyses were used to examine the odds ratios and 95 % confidence intervals (CIs) of the prevalence of the highest quartile of the homeostasis model assessment of IR (HOMA-IR) according to the ALT quartile. The cutoff value of ALT for the highest HOMA-IR quartile (Q4) were obtained using receiver operating characteristic curve analysis.

RESULTS

The mean ALT value increased as the number of metabolic syndrome components increased, but in only boys (p for trend <0.001), while the IR quartile increased in both boys and girls (all p for trends <0.001). The prevalence of IR (Q4) was only increased in ALT (Q4) in boys after the adjustment for age, body mass index, and waist circumference (OR 2.49; 95 % CI 1.05-5.91; p for trend = 0.017). The cutoff values were 17.0 IU/L in boys and 11.0 IU/L in girls.

CONCLUSIONS

The highest ALT quartile was associated with an increased prevalence of the highest quartile of IR in boys but not in girls.

Can "healthy" normal alanine aminotransferase levels identify the metabolically obese phenotype? Findings from the Korea national health and nutrition examination survey 2008-2010

BACKGROUND

There is no established parameter with which to screen metabolically obese phenotypes.

AIM

The aim of the study was to revise the upper limit of normal (ULN) of serum alanine aminotransferase (ALT) and to investigate the predictive value of updated ALT levels for metabolic obese phenotype stratified according to body mass index (BMI).

METHODS

We analyzed a nationally representative data from the Fourth Korea National Health and Nutrition Examination Survey. This cross-sectional study included 2,416 healthy people aged 33.9 ± 0.3 years. The ULN of healthy ALT level was set at the 95th percentile of the healthy population. A metabolic obese phenotype was defined as having insulin resistance or metabolic syndrome. A logistic regression analysis was performed to assess the odds ratio for a metabolic obese phenotype according to the healthy ALT level.

RESULTS

The revised ULN of serum ALT level in healthy participants were 30 IU/L and 22 IU/L for males and females, respectively. Serum ALT level was higher in individuals with metabolic obesity compared with those without metabolic obesity in both genders, stratified according to BMI. After adjusting for age, BMI, smoking, alcohol drinking, and regular physical activity, unhealthy normal ALT levels (males 30-40 IU/L, females 22-40 IU/L) were significantly associated with metabolic obesity, especially in both obese and non-obese women.

CONCLUSIONS

A newly revised threshold for ALT is proposed as a simple clinical metabolic parameter that can identify a metabolic obese phenotype. We suggest that people with unhealthy normal ALT levels may need further investigation for the presence of metabolic obesity.

Alanine aminotransferase-old biomarker and new concept: a review

Measurement of serum alanine aminotransferase (ALT) is a common, readily available, and inexpensive laboratory assay in clinical practice. ALT activity is not only measured to detect liver disease, but also to monitor overall health. ALT activity is influenced by various factors, including viral hepatitis, alcohol consumption, and medication. Recently, the impact of metabolic abnormalities on ALT variation has raised concern due to the worldwide obesity epidemic. The normal ranges for ALT have been updated and validated considering the metabolic covariates in the various ethnic districts. The interaction between metabolic and demographic factors on ALT variation has also been discussed in previous studies. In addition, an extremely low ALT value might reflect the process of aging, and frailty in older adults has been raised as another clinically significant feature of this enzyme, to be followed with additional epidemiologic investigation. Timely updated, comprehensive, and systematic introduction of ALT activity is necessary to aid clinicians make better use of this enzyme.

Liver function test changes in centrally obese youth with metabolic syndrome in a Serbian population

OBJECTIVE

The aim of this study was to investigate the association between metabolic syndrome and liver enzymes in overweight and obese adolescents and young adults.

METHODS

A total of 126 overweight and obese adolescents and young adults (age, 15-26 years), 55 (43.6%) with metabolic syndrome and 71 (56.4%) without metabolic syndrome, were studied.

RESULTS

Patients with metabolic syndrome had significantly higher alanine aminotransferase (ALT), γ-glutamyl transpeptidase (GGT), and alkaline phosphatase (ALP) levels compared to patients without metabolic syndrome [36.5±22.2 vs. 29.4±17.8 IU/L (P=0.043), 33.8±17.8 vs. 26.9±18.4 IU/L (P=0.002), and 84.3±32.2 vs. 75.7±29.5 IU/L (P=0.063)]. Aspartate aminotransferase (AST) levels were similar in both groups (24.1±9.8 vs. 23.3±9.0 IU/L, P=0.674). Elevated AST, ALT, GGT, and ALP levels were observed in 6, 15, 18, and 5 patients (11%, 27%, 14%, and 9%) with metabolic syndrome compared to 6, 17, 6, and 4 (8%, 24%, 8% and 5%) patients without metabolic syndrome (P=0.872, P=0.826, P<0.001, and P=0.035). In multivariate regression models adjusted for age and gender, metabolic syndrome was not a significant predictor of ALT (P=0.967), GGT (P=0.526), and ALP levels (P=0.221), but insulin resistance was a significant predictor for ALT and GGT levels (P=0.001, P=0.028).

CONCLUSION

Changes in liver function tests were observed in obese patients with metabolic syndrome, compared to patients without metabolic syndrome, especially in ALT and GGT levels. Insulin resistance is an independent pathogenic mechanism in liver function test changes regardless of metabolic syndrome in nondiabetic centrally obese youth.

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.

Targeted hepatic sonography during clinic visits for detection of fatty liver in overweight children: a pilot study

OBJECTIVES

The purpose of this study was to assess the feasibility and utility of targeted hepatic sonography to evaluate for hepatic steatosis during a subspecialty clinic visit.

METHODS

In this pilot study, we performed targeted hepatic sonography on 25 overweight children aged 7 to 17 years consecutively seen in a pediatric obesity clinic. Long-axis images of the right lobe of the liver and a split-screen image of liver and spleen were taken. Images were interpreted in real time by the radiologist and shown to the family. Demographics, clinical measurements, and laboratory parameters were also collected from the specialty clinic visit on the same day.

RESULTS

Sonography required a median of 4 minutes during the visit (interquartile range, 3-5 minutes). All consented patients completed the study. The median alanine aminotransferase (ALT) level was 23 U/L in those with no steatosis (n = 14), 26 U/L with mild steatosis (n = 6), and 41 U/L with moderate/marked steatosis (n = 5). Children with ALT levels of 25 to 50 U/L had very variable sonographic measures of hepatic steatosis. When the participants were categorized by the overall degree of fatty liver, hepatic steatosis was significantly associated with the aspartate aminotransferase level (P = .028), ALT level (P = .003), and diastolic blood pressure (P = .05) but did not correlate with age, sex, Latino race, or insulin resistance.

CONCLUSIONS

Targeted hepatic sonography added information not apparent from routine ALT screening and provided immediate feedback to clinicians and families about the effect of obesity on end organs. This examination could be a feasible, informative addition to screening for children at high risk for nonalcoholic fatty liver disease who are seen in clinics that specialize in obesity.

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.

Combined effects of hepatitis B virus infection and elevated alanine aminotransferase levels on dyslipidemia

OBJECTIVE

Although elevated alanine aminotransferase (ALT) levels are associated with lipid profiles, most studies do not consider the role of hepatitis B virus (HBV) infection. This study investigated the combined effects of HBV infection and elevated ALT levels on the lipid profiles of Taiwanese adults.

MATERIALS/METHODS

A total of 7695 subjects were enrolled after an annual health examination. Dyslipidemia was defined as serum total cholesterol≥200 mg/dL, serum triglyceride≥150 mg/dL, high-density lipoprotein cholesterol<40 mg/dL in men or <50 mg/dL in women, or low-density lipoprotein cholesterol≥130 mg/dL. Multiple logistic regression analysis was performed to assess the associations between dyslipidemia, HBV infection, and elevated ALT levels.

RESULTS

Hepatitis B surface antigen positivity (HBV[+]) and elevated ALT levels (ALT[+], ≥50 U/L) were observed in 13.5% and 12.2% of the subjects, respectively. Multiple logistic analysis revealed that the HBV(+) group had a significantly lower odds ratios (ORs) for hypercholesterolemia (OR, 0.8), hypertriglyceridemia (OR, 0.7), and high low-density lipoprotein cholesterol levels (OR, 0.8); whereas, the subjects with elevated ALT levels had significantly higher ORs for all of the dyslipidemia criteria. The interaction between HBV(+) and ALT(+) had a significantly lower OR for hypertriglyceridemia (OR, 0.7). The subjects with HBV infections had a significantly lower OR for hypertriglyceridemia regardless of the ALT levels.

CONCLUSIONS

HBV infection and elevated ALT levels have opposite effects on dyslipidemia, whereas their combined effects result in a significantly lower OR for hypertriglyceridemia.

Association between metabolic abnormalities and HBV related hepatocelluar carcinoma in Chinese: a cross-sectional study

Background

Previous studies suggested that the abnormality of metabolism is a newly identified risk factor in HBV-related hepatocellular carcinoma (HCC). The association between metabolic factors and hepatocellular carcinoma (HCC) has not been clarified up to now. This study was conducted to investigate the prevalence of metabolic abnormalities in HCC and to probe the association between metabolic parameters and liver function as well, so as to evaluate the interactions between metabolism and the development of HBV-related HCC.

Methods

Totally 179 cases of HBV-related HCC, who were surgically treated and pathologically confirmed were enrolled. HBV carriers (n = 100) and healthy controls (n = 150) were recruited from routine physical examination during the same period. Body mass index (BMI) was obtained from medical documentation. All the metabolic-related parameters and liver function tests were determined with routine biochemical or immunological analytic methods. Malondialdehyde (MDA) and total antioxidant capacity(TAOC)were detected by chemical analytic methods. A stratified analysis was conducted according to BMI, glycated albumin (GA), free fatty acids (FFA), and the relationships between the metabolic-related parameters and liver functions were analyzed in HCC and control subjects.

Results

HCC group showed significantly high levels of mean BMI, serum glucose, low serum lipids levels than controls (P < 0.05). Acquired by stratified analysis, the higher the BMI, the higher level of insulin and homeostasis model assessment for insulin resistance (HOMA-IR) (P < 0.01) were found in HCC patients. Elevated level of MDA and γ-glutamyltransferase (GGT) were revealed in those with high serum FFA level for the first time. Strong associations between metabolic factors and liver function were shown in HCC (P < 0.05). Higher GA level was strongly associated with increased risk of cancer compared to healthy controls (OR = 9.87, 95% confidence interval: 1.86~52.29). Serum triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels were negative contributory factors for HCC (OR = 0.05, 95% confidence interval: 0.01~0.27 and OR = 0.32, 95% confidence interval, 0.11~0.95: respectively).

Conclusions

Metabolic abnormalities are closely associated with the occurrence and development of HBV-related HCC. Oxidative stress and/or lipid peroxidation might be involved in the pathogenesis and acceleration of liver function impairments in HCC.

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.

Healthy range for serum ALT and the clinical significance of "unhealthy" normal ALT levels in the Korean population

BACKGROUND AND AIMS

It remains unclear whether the currently-used normal range for serum alanine aminotransferase (ALT) levels really reflects a healthy liver. The present study was conducted to evaluate the healthy range of serum ALT in the Korean adult population and to determine the clinical significance of unhealthy levels.

METHODS

We reviewed the medical records, including questionnaires and the results of laboratory and radiological tests conducted at the Health Promotion Center at Korea University Anam Hospital between March 2005 and February 2007. The records, written in questionnaire form, included baseline data, such as physical status, social behaviors, medication history, and past and present disease histories.

RESULTS

The mean age of the 7403 enrolled patients was 48 years, and 49.9% of these patients were male. A healthy cohort was selected after excluding patients who showed any abnormalities of the factors that were significantly associated with the serum ALT level upon multivariate regression analysis. The upper limit of the healthy range of the serum ALT level (i.e. 95th percentile) in the healthy population was 31 IU/L for males and 23 IU/L for females. The prevalence of metabolic syndrome and insulin resistance (IR) were significantly higher in patients with an 'unhealthy' normal ALT level than in those with a healthy ALT level.

CONCLUSION

In our study, the upper limit of the healthy range of the serum ALT level was 31 IU/L for males and 23 IU/L for females. An unhealthy normal ALT level was associated with a higher prevalence of metabolic syndrome and IR.