Alanine aminotransferase elevation not associated with fatty liver is frequently seen in obese Japanese women

Progress in the search for circulating biomarkers of nonalcoholic fatty liver disease

CONTEXT

The definitive standard for the diagnosis of nonalcoholic fatty liver disease (NAFLD) is clinico-pathological correlation, but frequently the only laboratory abnormality is an elevation of serum aminotransferases.

OBJECTIVE

This has resulted in the search for more specific laboratory biomarkers.

METHODS

The literature was searched for novel plasma/serum markers of NAFLD.

RESULTS

Studies reviewed here included histologically-confirmed patients presenting some stage of NAFLD and monitored one or more novel serum/plasma biomarkers.

CONCLUSION

The most promising application of some of these novel biomarkers for the detection and quantification of NAFLD and particularly NASH appears to be in the combination of several into diagnostic panels.

Serum alanine aminotransferase concentration as a predictive factor for the development or regression of fatty liver

Serum alanine aminotransferase (ALT) concentration is the most commonly used marker for hepatocellular injury. We investigated the suitable cutoff value of serum ALT for the diagnosis or prediction of fatty liver. In 1578 Japanese adults (1208 men, 370 women; 35–69 years of age) who visited our center both in 2000 and between April 2007 and March 2008 (2007–2008), serum ALT concentration was an independent predictor of fatty liver in men in 2000 and in both sexes in 2007–2008. A significant increase in the frequency of fatty liver was detected in participants with elevated serum ALT concentrations, and serum levels of ALT in 2000 were associated with fatty liver in 2007–2008 when the cutoff value was set at 30 IU/L in men and 19 IU/L in women. The frequency of fatty liver in 2007–2008 was significantly lower in participants without fatty liver in 2000 whose serum ALT decreased between 2000 and 2007–2008. Our results suggest that serum ALT might be not only an indicator of fatty liver but also a predictor of the regression of fatty liver, and cutoff values of serum ALT of 30 IU/L in men and 19 IU/L in women are suitable for the screening of fatty liver.

Gender difference of alanine aminotransferase elevation may be associated with higher hemoglobin levels among male adolescents

BACKGROUND

To explore the gender difference of ALT elevation and its association with high hemoglobin levels.

METHODS

A cross-sectional study of 3547 adolescents (2005 females, mean age of 16.5?.3 years) who were negative for hepatitis B surface antigen received health checkups in 2006. Body mass index (BMI), levels of hemoglobin, ALT and cholesterol were measured. ALT >42 U/L was defined as elevated ALT. Elevated ALT levels were detected in 112 of the 3547 participants (3.3%), more prevalent in males than in females (5.4% vs. 1.4%, p<0.001). Hemoglobin levels had a significant linear correlation with ALT levels in both genders. Abnormal ALT started to occur if hemoglobin >11 g/dl in females or >13.5 g/dl in males, but the cumulative cases of elevated ALT increased more quickly in males. Proportion of elevated ALT increased as either the BMI or hemoglobin level rise, more apparent in male adolescents. Logistic regression modeling showed odds ratio (95% confidence interval) were 24.7 (15.0-40.6) for BMI ≥27 kg/m(2); 5.5 (2.9-10.4) for BMI 24-27 kg/m(2); 2.7 (1.3-5.5) for Q5 (top 20th percentile) hemoglobin level; and 2.6 (1.6-4.1) for male gender. Further separately fitting the logistic models for two genders, the significance of Q5 hemoglobin level only appeared in the males.

CONCLUSIONS

High hemoglobin level is a significant risk factor of ALT elevation after control hepatitis B, obesity and gender. Males have greater risk of abnormal liver function which may be associated with higher hemoglobin levels.

Estimation of the healthy upper limits for serum alanine aminotransferase in Asian populations with normal liver histology

A recent study in young Italian subjects suggested that the healthy thresholds for serum alanine aminotransferase (ALT) levels should be adjusted to 30 IU/L for men and 19 IU/L for women when assessing risk factors for nonalcoholic fatty liver disease. Our aim was to assess serum ALT concentrations in healthy Korean individuals and to determine the factors affecting ALT levels in these populations. We included 1,105 potential liver donors (643 men and 462 women) with biopsy-proven normal livers. Median ages were 25 years in men and 30 years in women, with a median body mass index (BMI) of 22.3 kg/m(2) in men and 21.4 kg/m(2) in women. The calculated thresholds for ALT values in these subjects were 35 IU/L for men and 26 IU/L for women. Age and BMI were independently correlated with ALT levels in both sexes, whereas serum total cholesterol concentration was significant only in men and blood glucose level only in women (P < 0.05). When we chose a subgroup of 665 individuals (346 men and 319 women) using Prati criteria, modified by the BMI cutoff points for Asians (<23 kg/m(2)), we found that the healthy ALT values were 33 IU/L for men and 25 IU/L for women. The mean ALT concentrations for subjects within the Prati criteria were significantly lower than for those outside the criteria (16.7 versus 19.5 IU/L for men, 12.8 versus 14.9 IU/L for women; P < 0.001).

CONCLUSION

The healthy ALT thresholds in biopsy-proven normal Asians were clearly lower than the previously accepted thresholds, as has also been noted in Europeans. Age, BMI, and/or other metabolic parameters significantly affect ALT levels, even in subjects with normal livers.

Visceral obesity and hypoadiponectinemia are significant determinants of hepatic dysfunction: An epidemiologic study of 3827 Japanese subjects

BACKGROUND AND AIM

Adiponectin is an anti-inflammatory and insulin-sensitizing adipocytokine, and its serum concentrations are reduced in obesity with visceral fat accumulation. Visceral fat accumulation is an independent determinant of elevated serum liver enzymes. Hypoadiponectinemia plays important roles in the clinical progression of nonalcoholic steatohepatitis. The aim of this study was to evaluate the relation between visceral fat area (VFA), serum adiponectin concentration, and biochemical liver tests, such as aspartate aminotransferase, alanine aminotransferase (ALT), and gamma-glutamyltransferase (GGT) in normal subjects.

METHODS

The study group comprised 3827 Japanese subjects [mean age+/-SD; 47.6+/-10.7 y: 2854 males (48.4+/-10.7 y), 973 females (45.3+/-10.1 y)], who underwent annual health checkup in 2004. In addition to parameters measured in the annual health checkup, VFA and serum adiponectin concentration were measured by the bioelectrical impedance analysis method and a latex particle-enhanced turbidimetric assay system, respectively.

RESULTS

Pearson's correlation analysis showed a significant correlation between VFA and the levels of the above 3 liver enzymes in both sexes, and a significant negative correlation between adiponectin and all biochemical liver tests in men and with ALT and GGT in women. Stepwise multiple regression analysis showed that VFA was a significant determinant of serum liver tests in both sexes. Moreover, serum adiponectin concentration significantly and negatively influenced male ALT and GGT and female GGT.

CONCLUSIONS

Both visceral obesity and hypoadiponectinemia are significant determinants of subtle and asymptomatic hepatic dysfunction in normal Japanese subjects.

Higher concentrations of alanine aminotransferase within the reference interval predict nonalcoholic fatty liver disease

BACKGROUND

In nonalcoholic fatty liver disease (NAFLD), increased alanine aminotransferase (ALT) concentrations are considered to be a consequence of hepatocyte damage. We performed a prospective study to examine the association between ALT within its reference interval and risk for subsequent development of NAFLD.

METHODS

The study cohort comprised 5237 healthy men without diagnosed NAFLD and without increases of either ALT (> or =35 U/L) or gamma-glutamyltransferase (GGT; > or =40 U/L) above the reference intervals. We assessed alcohol intake via self-reporting (questionnaire) and performed biochemical tests for liver and metabolic function and abdominal ultrasonography. We used the Cox proportional hazards model to calculate the adjusted hazard ratios (aHRs) in the model for NAFLD.

RESULTS

During 13 276.6 person-years of follow-up over a 4-year period, 984 new incident cases of NAFLD developed. We adjusted for age, weight change, body mass index, glucose, blood pressure, triglycerides, HDL cholesterol, smoking, alcohol consumption, regular exercise, homeostasis model assessment of insulin resistance, C-reactive protein, and incident diabetes. Compared with an ALT concentration of <16 U/L, aHR values (95% confidence intervals) for ALT concentrations were 1.53 (1.18-1.98), 1.66 (1.29-2.13), 1.62 (1.26-2.08), and 2.21 (1.73-2.81) for ALT concentrations of 16-18, 19-21, 22-25, and 26-34 U/L, respectively. This relationship remained significant even among normal-weight participants who were still within the reference interval of ALT and GGT at all follow-up examinations.

CONCLUSIONS

In apparently healthy, nondiabetic Korean men, increased ALT concentration, even within the reference interval, was an independent predictor of incident NAFLD.

Associations between gamma-glutamyl transferase, metabolic abnormalities and inflammation in healthy subjects from a population-based cohort: a possible implication for oxidative stress

AIM

To examine the relationships between gamma-glutamyl-transferase (GGT), alanine-aminotransferase (ALT), aspartate-aminotransferase (AST) and various metabolic parameters, C-reactive protein (CRP) and an oxidative stress marker (nitrotyrosine, NT) in subjects without any metabolic abnormalities from a population-based sample.

METHODS

Two hundred and five subjects with normal body mass index (BMI), glucose tolerance, and without any metabolic abnormality were studied out of 1 339 subjects, without known liver diseases, alcohol abuse or use of hepatotoxic drugs, who are representative of the 45-64 aged population of Asti (north-western Italy).

RESULTS

In all patients metabolic parameters and hs-CRP levels linearly increase from the lowest to the highest ALT and GGT tertiles, while in subjects without metabolic abnormalities, there is a significant association between fasting glucose, uric acid, waist circumference, hs-CRP, triglyceride values, and GGT levels. In these subjects, male sex, higher hs-CRP and glucose levels are associated with GGT levels in a multiple regression model, after adjustments for multiple confounders. In the same model, median NT levels are significantly associated with the increasing GGT tertile (beta = 1.06; 95%CI 0.67-1.45), but not with the AST and ALT tertiles. In a multiple regression model, after adjusting for age, sex, BMI, waist, smoking, and alcohol consumption, both NT (beta = 0.05; 95%CI 0.02-0.08) and hs-CRP levels (beta = 0.09; 95%CI 0.03-0.15) are significantly associated with fasting glycemia.

CONCLUSION

GGT, an easy, universally standardized and available measurement, could represent an early marker of sub-clinical inflammation and oxidative stress in otherwise healthy individuals. Prospective studies are needed to establish if GGT could predict future diabetes in these subjects.