Dose response of laboratory markers to alcohol consumption in a general population

Gamma-glutamyltransferase predicts macrovesicular liver graft steatosis - an analysis of discarded liver allografts in Finland

OBJECTIVE

Liver-transplantation activity is limited by the shortage of grafts. Donor-liver macrovesicular steatosis predisposes to ischemia-reperfusion injury and is associated with reduced graft survival. The increasing prevalence of fatty-liver disease underlines the importance of identifying macrovesicular steatosis in potential donor livers. We analyzed liver grafts discarded for transplantation, and particularly the role of gamma-glutamyltransferase (GGT) in predicting graft steatosis.

METHODS

One-hundred sixty rejected cadaveric-donor liver grafts were studied. Donor selection was based on clinical data, and macroscopic graft inspection. Discarded grafts were biopsied at procurement of non-liver organs.

RESULTS

The most common reasons for discarding the graft were abnormal liver tests, ultrasound-verified steatosis and history of harmful alcohol use. GGT correlated moderately with macrovesicular steatosis (r = 0.52, p < 0.001), but poorly with microvesicular steatosis (r = 0.36, p < 0.001). Increased correlation between GGT and macrovesicular steatosis was observed among alcohol abusers (r = 0.67, p < 0.001). Area under the curve (AUC) of GGT for predicting >30% macrovesicular steatosis was 0.79 (95% CI 0.71-0.88), and for >60% steatosis, 0.79 (95% CI 0.68-0.90). The optimal GGT-cut off for detecting >30% and >60% macrovesicular steatosis were, respectively, 66 U/L (sensitivity 76% and specificity 68%) and 142 U/L (sensitivity 66% and specificity 83%). Among alcohol users, a GGT value >90 U/L showed 100% sensitivity for >60% macrovesicular steatosis. AUC for GGT in predicting fibrosis Stages 2-4 was 0.82 (95% CI 0.71-0.92, p < 0.001, optimal cut off 68, sensitivity 92%, specificity 61%).

CONCLUSIONS

Abnormal liver values, steatosis and harmful alcohol use were the main reasons for discarding liver-graft offers in Finland. GGT proved useful in predicting moderate and severe liver graft macrovesicular steatosis.

Risk assessment of low-dose ethanol in food

A high variety of food contains low doses of ethanol which are sometimes difficult to identify by consumers (adults or children). However, even low doses of ethanol intake raises several toxicological concerns. In the present study, an enzymatic assay and an HS-GC/MS procedure were applied to determine the ethanol levels of 1260 samples from different food categories covering "nonalcoholic" beer, fruit juices/drinks, baked goods, bananas and baby foods. Based on these results, ethanol levels resulting from acute or chronic ethanol intake was calculated using consumption data from the EFSA Comprehensive European Food Consumption Database. Thus, health-based guidance values (HBGV) for ethanol intake were derived for acute or chronic exposure based on the available literature. For acute exposure, very few samples resulted in concerning ethanol uptake levels but following chronic exposure the here derived HBGV level was exceeded in several cases. This is mainly due to the following reasons: (1) certain amounts of ethanol are still tolerated in "nonalcoholic" beer and (2) presence of endogenous produced ethanol in bananas or baked goods via fermentation. Most analysed food samples, however, do not result in elevated ethanol doses linked with a potentially high risk following acute and chronic consumption by adults and children.

Significance of Fib4 index as an indicator of alcoholic hepatotoxicity in health examinations among Japanese male workers: a cross-sectional and retrospectively longitudinal study

BACKGROUND

Fib4 index (Fib4) is clinically used as a noninvasive marker of liver fibrosis. In this study, we aimed to preliminarily investigate whether Fib4 can be used to detect individuals who need assessment for alcoholic liver disease (ALD) in the general population by clarifying the detailed association of Fib4 with alcohol consumption and gamma-glutamyl transferase (GGT) among male workers.

METHODS

We analyzed data sets on the comprehensive medical examinations of male workers as cross-sectional and retrospectively longitudinal studies. We enrolled 10 782 males (mean age: 52.2 ± 10.2 years) in FY2019 and 7845 males (mean follow-up: 12.6 ± 6.7 years) who could be consecutively followed up for 20 years from FY2000 to FY2019. Data were evaluated using logistic regression and COX proportional analysis.

RESULTS

In the cross-sectional setting, the rate of Fib4 ≥ 2.67 in heavy drinkers (≥ 40 g of ethanol/day) was increased dose dependently in those over 65 years old, and that of body mass index ≥ 30 kg/m² was increased in those over 60 years old, but not in those with fatty liver. The odds ratio (OR) (95% confidence interval [CI]) for heavy drinking was 4.30 (95% CI = 1.90-9.72), and GGT ≥ 200 IU/L was considerably high (OR = 29.05 [95% CI = 17.03-49.56]). In the longitudinal setting, heavy drinkers and those with GGT ≥ 200 IU/L at 10 years after the baseline showed an increased risk for Fib4 ≥ 2.67 (hazard ratio = 2.17 [95% CI = 1.58-2.98] and 7.65 [95% CI 5.26-11.12], respectively).

CONCLUSIONS

The development of Fib4 ≥ 2.67 after 10 years was associated with heavy alcohol drinking and GGT level ≥ 200 IU/L. Therefore, Fib4 combined with GGT could indicate high risk of ALD. However, clinical examinations and course observations are essentially needed.

Development and validation of a model to predict incident chronic liver disease in the general population: The CLivD score

BACKGROUND & AIMS

Current screening strategies for chronic liver disease focus on detection of subclinical advanced liver fibrosis but cannot identify those at high future risk of severe liver disease. Our aim was to develop and validate a risk prediction model for incident chronic liver disease in the general population based on widely available factors.

METHODS

Multivariable Cox regression analyses were used to develop prediction models for liver-related outcomes with and without laboratory measures (Model_lab and Model_non-lab) in 25,760 individuals aged 40-70 years. Their data were sourced from the Finnish population-based health examination surveys FINRISK 1992-2012 and Health 2000 (derivation cohort). The models were externally validated in the Whitehall II (n = 5,058) and Copenhagen City Heart Study (CCHS) (n = 3,049) cohorts.

RESULTS

The absolute rate of incident liver outcomes per 100,000 person-years ranged from 53 to 144. The final prediction model included age, sex, alcohol use (drinks/week), waist-hip ratio, diabetes, and smoking, and Model_lab also included gamma-glutamyltransferase values. Internally validated Wolbers' C-statistics were 0.77 for Model_lab and 0.75 for Model_non-lab, while apparent 15-year AUCs were 0.84 (95% CI 0.75-0.93) and 0.82 (95% CI 0.74-0.91). The models identified a small proportion (<2%) of the population with >10% absolute 15-year risk for liver events. Of all liver events, only 10% occurred in participants in the lowest risk category. In the validation cohorts, 15-year AUCs were 0.78 (Model_lab) and 0.65 (Model_non-lab) in the CCHS cohort, and 0.78 (Model_non-lab) in the Whitehall II cohort.

CONCLUSIONS

Based on widely available risk factors, the Chronic Liver Disease (CLivD) score can be used to predict risk of future advanced liver disease in the general population.

LAY SUMMARY

Liver disease often progresses silently without symptoms and thus the diagnosis is often delayed until severe complications occur and prognosis becomes poor. In order to identify individuals in the general population who have a high risk of developing severe liver disease in the future, we developed and validated a Chronic Liver Disease (CLivD) risk prediction score, based on age, sex, alcohol use, waist-hip ratio, diabetes, and smoking, with or without measurement of the liver enzyme gamma-glutamyltransferase. The CLivD score can be used as part of health counseling, and for planning further liver investigations and follow-up.

Measurement error as an explanation for the alcohol harm paradox: analysis of eight cohort studies

BACKGROUND

Despite reporting lower levels of alcohol consumption, people with lower socio-economic status (SES) experience greater alcohol-related harm. Whether differential biases in the measurement of alcohol use could explain this apparent paradox is unknown. Using alcohol biomarkers to account for measurement error, we examined whether differential exposure to alcohol could explain the socio-economic differences in alcohol mortality.

METHODS

Participants from eight representative health surveys (n = 52 164, mean age 47.7 years) were linked to mortality data and followed up until December 2016. The primary outcome was alcohol-attributable mortality. We used income and education as proxies for SES. Exposures include self-reported alcohol use and four alcohol biomarkers [serum gamma-glutamyl transferase (available in all surveys), carbohydrate-deficient transferrin, alanine aminotransferase and aspartate aminotransferase (available in subsamples)]. We used shared frailty Cox proportional hazards to account for survey heterogeneity.

RESULTS

During a mean follow-up of 20.3 years, totalling 1 056 844 person-years, there were 828 alcohol-attributable deaths. Lower SES was associated with higher alcohol mortality despite reporting lower alcohol use. Alcohol biomarkers were associated with alcohol mortality and improved the predictive ability when used in conjunction with self-reported alcohol use. Alcohol biomarkers explained a very small fraction of the socio-economic differences in alcohol mortality, since hazard ratios either slightly attenuated (percent attenuation range 1.0-12.1%) or increased.

CONCLUSIONS

Using alcohol biomarkers in addition to self-reported alcohol use did not explain the socio-economic differences in alcohol mortality. Differential bias in the measurement of alcohol use is not a likely explanation for the alcohol-harm paradox.

Biomarker and Genomic Risk Factors for Liver Function Test Abnormality in Hazardous Drinkers

BACKGROUND

Alcohol dependence and long-term excessive alcohol use may cause liver damage, but only some patients develop cirrhosis. Similarly, high alcohol intake without evident liver disease often but not always produces abnormal enzymatic liver function tests (LFTs), particularly gamma-glutamyl transferase (GGT). We postulate that the factors predisposing to cirrhosis in alcoholics and to liver enzyme abnormality in drinkers are similar, and that biochemical LFTs could therefore be useful as markers of risk of alcoholic liver disease in excessive drinkers.

METHODS

Data from participants in twin and twin-family studies on alcohol use and dependence were used to identify 1,003 people who had reported excessive alcohol intake (28 drinks or more per week). A total of 962 of these provided blood for biochemical tests at the same time. Body mass index (BMI) and biomarkers of metabolic syndrome, inflammation, and iron stores were used in logistic regression with abnormality in serum GGT, alanine aminotransferase (ALT), or aspartate aminotransferase (AST) as outcomes. We conducted genome-wide association analyses for GGT, ALT, and AST separately in the group reporting excessive alcohol intake (N = 951) and a low-intake group reporting 14 drinks or fewer per week (N = 8,716), and compared results.

RESULTS

Abnormal GGT and ALT among excessive drinkers were associated with higher BMI, triglycerides, insulin, uric acid, C-reactive protein, ferritin, and transferrin saturation; and with lower high-density-lipoprotein cholesterol. Abnormal AST was associated with triglycerides, ferritin, and transferrin saturation. ALT was significantly associated with variants at reported genetic loci for alcoholic liver disease (PNPLA3, rs738409, p = 0.0076; TM6SF2, rs10401969, p = 0.0076; HSD17B13, rs10433879, p = 0.0024).

CONCLUSIONS

Known risk factors for alcoholic cirrhosis including obesity and markers of metabolic syndrome, iron overload and inflammation are associated with liver enzyme abnormality in excessive drinkers.

Binge Drinking Episodes in Young Adults: How Should We Measure Them in a Research Setting?

OBJECTIVE

Worldwide, consequences of binge drinking are a major health and policy concern. This article reviews contemporary binge drinking definitions as well as different questionnaires and biomarkers that have been used in research settings to examine binge drinking behavior among young adults.

METHOD

A review of electronic databases was conducted for binge drinking definitions, questionnaires, and biomarkers for the measurement of binge drinking in young adults (18-30 years).

RESULTS

Binge drinking is often defined as four or more drinks for females and five or more drinks for males on an occasion or in one sitting within a designated time frame (2 weeks vs. past 30 days). Several tools and questionnaires are available to identify young adult repeated binge drinkers. Biomarkers have been used to corroborate self-reported alcohol consumption, of which direct biomarkers such as phosphatidylethanol may be useful in confirming recent heavy drinking.

CONCLUSIONS

It is important to measure binge drinking along a continuum and to use questions that allow for assessment of intensity, frequency, duration, and daily versus weekend consumption patterns. Open-ended questions that allow for intensity (number of drinks) and frequency can be used to determine dose-response relationships with respect to specific outcome measures. Direct alcohol biomarkers reflecting alcohol consumption over a period of several days are useful in conjunction with questionnaire data for identifying young adult binge drinkers.

Diagnostic sensitivity of carbohydrate deficient transferrin in heavy drinkers

Background and Aim

Carbohydrate deficient transferrin (CDT) is the most specific serum biomarker of heavy alcohol consumption, defined as ≥ 350–420 g alcohol/week. Despite introduction of a standardized reference measurement technique, widespread use of CDT remains limited due to low sensitivity. The aim of this study was to determine the factors that affect diagnostic sensitivity in patients with sustained heavy alcohol intake.

Methods

Patients with a self-reported history of sustained heavy alcohol consumption were recruited from the hepatology outpatient department or medical wards. Each patient was interviewed with a validated structured questionnaire of alcohol consumption and CDT analysis using the standardized reference measurement technique with high performance liquid chromatography was performed on serum collected at time of interview.

Results

52 patients were recruited: 19 from the hepatology outpatient department and 33 from general medical wards. Median alcohol intake was 1013 (range 366–5880) g/week over the preceding two week period. 26 patients had a diagnostic CDT based on a threshold value of %CDT > 1.7 indicating heavy alcohol consumption, yielding a sensitivity of 50%. Overweight/obesity (defined as body mass index (BMI) ≥ 25 kg/m² in Caucasians and ≥ 23.0 kg/m² in Asians), female gender and presence of cirrhosis were independently associated with non-diagnostic %CDT (≤ 1.7).

Conclusions

CDT has limited sensitivity as a biomarker of heavy alcohol consumption. Caution should be applied when ordering and interpreting %CDT results, particularly in women, patients with cirrhosis and those with an elevated BMI.

How accurate are blood (or breath) tests for identifying self-reported heavy drinking among people with alcohol dependence?

AIMS

Managing patients with alcohol dependence includes assessment for heavy drinking, typically by asking patients. Some recommend biomarkers to detect heavy drinking but evidence of accuracy is limited.

METHODS

Among people with dependence, we assessed the performance of disialo-carbohydrate-deficient transferrin (%dCDT, ≥1.7%), gamma-glutamyltransferase (GGT, ≥66 U/l), either %dCDT or GGT positive, and breath alcohol (> 0) for identifying 3 self-reported heavy drinking levels: any heavy drinking (≥4 drinks/day or >7 drinks/week for women, ≥5 drinks/day or >14 drinks/week for men), recurrent (≥5 drinks/day on ≥5 days) and persistent heavy drinking (≥5 drinks/day on ≥7 consecutive days). Subjects (n = 402) with dependence and current heavy drinking were referred to primary care and assessed 6 months later with biomarkers and validated self-reported calendar method assessment of past 30-day alcohol use.

RESULTS

The self-reported prevalence of any, recurrent and persistent heavy drinking was 54, 34 and 17%. Sensitivity of %dCDT for detecting any, recurrent and persistent self-reported heavy drinking was 41, 53 and 66%. Specificity was 96, 90 and 84%, respectively. %dCDT had higher sensitivity than GGT and breath test for each alcohol use level but was not adequately sensitive to detect heavy drinking (missing 34-59% of the cases). Either %dCDT or GGT positive improved sensitivity but not to satisfactory levels, and specificity decreased. Neither a breath test nor GGT was sufficiently sensitive (both tests missed 70-80% of cases).

CONCLUSIONS

Although biomarkers may provide some useful information, their sensitivity is low the incremental value over self-report in clinical settings is questionable.

Individual and joint impacts of ethanol use, BMI, age and gender on serum gamma-glutamyltransferase levels in healthy volunteers

Excessive ethanol consumption, obesity and increasing age may all lead to increased serum levels of gamma-glutamyltransferase (GGT) enzyme, which plays a key role in the metabolism of extracellular reduced glutathione. However, as yet, the interactions between the various modulators of GGT activities have remained poorly defined. We analyzed data from 15,617 apparently healthy individuals (7254 men and 8363 women, mean age 46 ± 13 years, range 25–74 years) who participated in a national cross-sectional health survey in Finland between 1997 and 2007. All subjects underwent detailed clinical examinations and interviews, including the amount of ethanol use and smoking habits. GGT levels were measured from all participants, and the individual and joint impacts of the different study variables on GGT levels were assessed. Significant individual effects were noted for ethanol use (p < 0.001), body mass index (BMI) (p < 0.001), age (p < 0.001) and smoking (p < 0.001). In men, significant two-factor interactions occurred between ethanol use and age (p < 0.020). Among those over 40 years of age, ethanol consumption was found to be a stronger determinant of increased GGT levels than in men below 40 years, whereas in the latter age group, BMI was found to predominate. In women, a significant two-factor interaction occurred between ethanol and BMI (p = 0.010), whereas it did not with ethanol use and age. The data underscores the role of ethanol consumption and age as major determinants of increased GGT levels in men, whereas in women, a relatively stronger impact was noted for ethanol intake and BMI. In light of the ability of GGT enzyme to modulate crucial redox-sensitive functions, the present findings also support the use of GGT as a biomarker of oxidative stress.

The effects of chronic cigarette smoking on cognitive recovery during early abstinence from alcohol

BACKGROUND

Alcohol use disorders are related to neurocognitive abnormalities during early abstinence in those seeking treatment for alcohol dependence (ALC). Considerable evidence indicates that chronic cigarette smoking is associated with multiple neurocognitive deficiencies. However, very little is known about the effects of chronic smoking on neurocognitive recovery during early abstinence from alcohol. We evaluated whether cigarette smoking interferes with cognitive improvement during early abstinence from alcohol, a period thought important for maintaining long-term sobriety.

METHODS

Neurocognitive functions previously shown to be adversely affected by both alcohol use disorders and chronic cigarette smoking were evaluated. We assessed 35 smoking ALC (sALC) and 34 nonsmoking ALC (nsALC) at approximately 1 and 5 weeks of monitored abstinence.

RESULTS

Although neither group was clinically impaired, both cross-sectional and longitudinal deficiencies were observed in sALC versus nsALC in processing speed, working memory, and auditory-verbal learning and memory. Lifetime alcohol consumption, medical, and psychiatric comorbidities did not predict neurocognitive performance or improvement across assessments. Within sALC, greater drinking and smoking severities were synergistically (more than additively) related to less improvement on visuospatial learning and memory. Former smoking status in the nsALC-mediated group differences in auditory-verbal delayed recall.

CONCLUSIONS

Chronic cigarette smoking appears to negatively impact neurocognition during early abstinence from alcohol. Although the cognitive deficiencies observed in this cohort were not in a clinical range of impairment, they should be considered to enhance treatment efficacy. Our findings lend support to integrating smoking cessation as well as the individual assessment of cognition into early ALC treatment. Additionally, there is a need to elucidate the effects of current and former smoking status in future reports of neurocognition.

Diagnosis and management of alcoholic hepatitis

Alcoholic hepatitis is a form of severe, cholestatic liver disease that results from consumption of large amount of alcohol during a sustained period of time in a subset of alcoholics. Symptoms could be mild and nonspecific to more severe. The diagnosis of alcoholic hepatitis can be made with a thorough history, physical examination, and review of laboratory results. Liver biopsy is confirmatory but generally not indicated for the diagnosis. Abstinence is the key form of therapeutic intervention. Despite variable results in clinical trials, corticosteroids and pentoxifylline seem to provide moderate survival benefit. Liver transplantation in acute alcoholic hepatitis is contentious.

Effect of age and gender on the relationship between alcohol consumption and serum GGT: time to recalibrate goals for normal ranges

AIMS

While serum gamma-glutamyltransferase (GGT) enzyme activity is a well established biomarker of excessive alcohol consumption and liver dysfunction, recent studies have also implicated it as a predictor of morbidity due to extrahepatic causes. Therefore, further information on the associations between ethanol intake and GGT activities in apparently healthy individuals appears warranted.

METHODS

Data on alcohol consumption and serum GGT activities were collected from 18,899 individuals (8807 men, 10,092 women), mean age 48 years and range 25-74 years, who participated in a national cross-sectional health survey. Alcohol use was assessed by detailed questionnaires and the study population was subsequently divided into subgroups according to age and gender. Body mass index and smoking were used as covariates in all analyses.

RESULTS

In men over 40 years, a reported regular consumption of 8 standard ethanol doses ('dose' = 12 g ethanol) or more per week was found to lead to a significant elevation in serum GGT activities, whereas those below 40 showed first significant changes not until the reported ethanol intake exceeded 14 doses per week. For women, the corresponding threshold levels were four and seven standard ethanol doses, respectively.

CONCLUSION

The data pertaining to the present population sample indicate that rather low levels of reported regular ethanol consumption lead to elevated levels of GGT and that age over 40 markedly enhances the impact of alcohol consumption on GGT activity. The present findings should form the basis for defining safe levels of ethanol consumption and in recalibrating goals for normal limits in the clinical use of GGT measurements.

Analysis of carbohydrate deficient transferrin serum levels during abstinence

An alcohol-associated change in the serum transferrin glycoform pattern, carbohydrate-deficient transferrin (CDT), is used as a biomarker of chronic moderate to heavy alcohol consumption. Furthermore, CDT is employed as a marker of abstinence. Here, we analyzed CDT in patients with chronic excessive alcohol abuse at the beginning and during abstinence. Twenty-nine alcohol dependent patients were recruited from an in-patient abstention program. Reported drinking levels were at least 100 g/d (range up to 450 g/d; mean: 248.9±94.7 g/d) within the last month before study entry. Blood samples were drawn at the beginning and during the abstention program and the relative concentration (%CDT) of CDT was determined using ion exchange followed by immunodetermination of CDT. At study entry, 25/29 patients had a %CDT level above the established cutoff. Although CDT levels declined during abstinence in most patients, in ten patients with %CDT levels just above the cutoff at the start of the program, the CDT values remained elevated 6 weeks after cessation of drinking. Our data indicate that %CDT levels below the cutoff cannot even rule out long lasting excessive alcohol abuse. Further, measurement of %CDT should be interpreted with special care when used as a marker of alcohol abstinence.

Gamma-glutamyltransferase, general and cause-specific mortality in 19,000 construction workers followed over 20 years

BACKGROUND & AIMS

Associations of serum gamma-glutamyltransferase levels with a variety of incident diseases and mortality have been suggested. The present study attempted to expand the body of evidence to especially relevant occupational cohorts in which exposure to established γ-GT determinants may greatly differ from the general population.

METHODS

The study was based on occupational health examinations conducted from 1986 to 1992 in 19,090 German male workers from the construction industry, aged 25-64years. Sociodemographics and other health-related information were collected during the exam. Vital status follow-up was conducted through 2008. Associations of baseline γ-GT levels (measurements at 25°C) with all-cause and cause-specific mortality were examined by Kaplan-Meier plotting and multiple adjusted Cox regression models.

RESULTS

A total of 2170 deaths occurred during 303,198 person-years of follow-up. The risk of death due to any cause was 2.5-fold increased in subjects in the highest (⩾39U/L) versus lowest (<11U/L) γ-GT quintile. To varying extents, elevated γ-GT was associated with higher mortality due to cancer, circulatory, respiratory, and digestive causes, as well as accidents/poisoning.

CONCLUSIONS

The findings in this cohort provide evidence for γ-GT being associated with a broad range of causes of death, including less investigated outcomes. Some characteristics of the observed patterns need to be seen in the context of our cohort, featuring particularly high γ-GT levels.

Smoking and γ-glutamyltransferase: opposite interactions with alcohol consumption and body mass index

Background

Smoking has recently been suggested to synergistically interact with alcohol intake as a determinant of serum gamma-glutamyltransferase (γ-GT), an emergent powerful predictor of disease and mortality. This study investigated whether this also applies to higher smoking and alcohol exposure ranges and to body mass index (BMI), which likewise is strongly associated with γ-GT.

Methodology/Principal Findings

Analyses were based on occupational health examinations of more than 15,000 German male workers aged 16–64 years, predominantly from the construction industry. Sociodemographics and other health-related information were collected during the exam. Joint associations of smoking and alcohol consumption or BMI with elevated or log-transformed γ-GT were examined by tabulation and multiple adjusted regression models. Cigarette smoking exerted no effect on γ-GT in teetotalers, but there was a statistically significant effect of smoking among participants with higher alcohol consumption intensity, odds of elevated γ-GT being increased by 24% and 27% per additional 10 cigarettes smoked per day in subjects drinking 61–90 and >90 gram alcohol per day, respectively (P for interaction = 0.039). The interaction was opposite for BMI, where no association was seen in obese subjects, whereas odds of elevated γ-GT were increased by 24% per 10 cigarettes below 25 kg/m² (P for interaction = 0.040). This novel interaction was replicable in an independent cohort.

Conclusion

The evidence for opposite interactions of smoking with alcohol and BMI as determinants of serum γ-GT suggests that different physiological pathways are responsible for the associations between these factors.

Epidemiology-based risk assessment using the benchmark dose/margin of exposure approach: the example of ethanol and liver cirrhosis

BACKGROUND

A novel approach to derive a threshold dose with respect to alcohol-related harm, the benchmark dose (BMD) methodology, is introduced to provide a basis for evidence-based drinking guidelines. This study is the first to calculate a BMD for alcohol exposure using epidemiological cohort data. With this BMD we will be able to calculate the margin of exposure (MOE) for alcohol consumption, which can be used for comparative risk assessment and applied to setting public health policy.

METHODS

Benchmark dose-response modelling of epidemiological data gathered during a recent systematic review and meta-analysis of alcohol consumption as a risk factor for liver cirrhosis morbidity and mortality.

RESULTS

For a benchmark response (BMR) of 1.5%, the resulting BMD values were 30.9 g/day for males and 29.7 g/day for females; the corresponding lower one-sided confidence values were 25.7 and 27.2 g/day, respectively. The intake scenario for the Canadian population resulted in an MOE of 1.23. Intake scenarios for individuals as based on the Canadian drinking guidelines led to MOE values between 0.96 and 1.91. Using an uncertainty factor of 10, the acceptable daily intake for alcohol would be 2.6 g/day.

CONCLUSIONS

The BMD approach was feasible in developing evidence-based guidelines for low-risk drinking. As our calculated MOEs result around unity (i.e. 1) for moderate drinking, it is evident that the current guidelines correspond very well to low risk on the dose-response curve. The BMD methodology therefore validates current guidelines. The results again highlight the health risk associated with alcohol consumption.

Predicting DUI recidivism of male drunken driving: a prospective study of the impact of alcohol markers and previous drunken driving

The aim of the present study was to determine whether the alcohol biomarkers CDT, GGT, the biomarker gamma-CDT index and previous drunken driving contributed significantly to the prediction of DUI recidivism. The subjects consisted of two different samples of drivers, viz. drivers who were found to have a positive breath alcohol concentration during random breath testing surveys (n=237), and drunken drivers who were apprehended during ordinary police work (n=193). The drunken driving events were monitored using a data-base both retrospectively and prospectively. It was found that the biomarker index, gamma-CDT, emerged as a notable predictor of recidivism in the group of random breath tested drivers. Measurement of gamma-CDT and its impact on DUI recidivism has not to our knowledge been applied to random breath tested drivers before. The apprehended drunken drivers, on the other hand, did not show a significant relationship between gamma-CDT and DUI recidivism. However, in both groups of drivers it was found that a previous conviction for drunken driving strongly predicted DUI recidivism. More attention should be paid by both physicians and the police to the high risk of recidivism among those convicted of drunken driving.

Alcoholic liver disease

These recommendations provide a data-supported approach. They are based on the following: (i) a formal review and analysis of the recently published world literature on the topic (Medline search); (ii) American College of Physicians Manual for Assessing Health Practices and Designing Practice Guidelines (1); (iii) guideline policies, including the American Association for the Study of Liver Diseases (AASLD) Policy on the development and use of practice guidelines and the AGA Policy Statement on Guidelines (2); and (iv) the experience of the authors in the specified topic. Intended for use by physicians, these recommendations suggest preferred approaches to the diagnostic, therapeutic, and preventive aspects of care. They are intended to be flexible, in contrast to the standards of care, which are inflexible policies to be followed in every case. Specific recommendations are based on relevant published information. To more fully characterize the quality of evidence supporting the recommendations, the Practice Guideline Committee of the AASLD requires a Class (reflecting the benefit vs. risk) and Level (assessing the strength or certainty) of Evidence to be assigned and reported with each recommendation (Table 1, adapted from the American College of Cardiology and the American Heart Association Practice Guidelines) (3,4).

[Does carbohydrate-deficient transferrin have diagnostic value in non-alcoholic fatty liver disease?]

Non-alcoholic fatty liver disease (NAFLD) is an acquired metabolic liver disease in the consequence of triglyceride accumulation within liver cells. It is accompanied by necrobiotic inflammatory reaction, fibrosis and also by liver cirrhosis. Its distinction from alcoholic fatty liver disease (AFLD) can be difficult. Clear anamnesis may help, but if the patient does not inform us about the alcohol consumption, the differentiation is not easy.

AIM

Our aim was to determine the value of carbohydrate deficient transferrin (CDT) in patients with non-alcoholic fatty liver disease, as well as to analyze the background of high CDT values, according to the anamnesis.

PATIENTS AND METHODS

39 patients (21 female and 18 male) with ultrasound signs of fatty liver disease were studied. CDT, body mass index (BMI) and HOMA index were determined.

RESULTS

Mean value of CDT was: 2.39+/-0.52% (in male 2.51+/-0.61, in female 2.28+/-0.4). No significant difference was found among the two sexes. The diversity of CDT values was normal. The value of BMI belonged to the overweight area without any significant difference between the two sexes.

CONCLUSION

On the basis of the results, NAFLD and AFLD can be differentiated according to the CDT value, and this value could be a higher specific value than the activity of gammaglutamyl transpeptidase, however, anamnesis and other factors are as well very important in achieving the correct diagnosis.

Synergism between smoking and alcohol consumption with respect to serum gamma-glutamyltransferase

There is increasing evidence that serum levels of the liver enzyme gamma-glutamyltransferase (gamma-GT) are an important predictor of incidence and mortality of various diseases. Apart from alcohol consumption, body mass index and smoking have been found to be associated with serum levels, but little is known about potential interactions of these factors. The aim of this study was to assess the individual and joint impact of alcohol consumption and smoking on levels of gamma-GT, with particular attention to potential differences by sex. The study was based on data of 8465 subjects aged 50 to 74 years, obtained at baseline examination of the ESTHER study, a large population-based cohort study in Germany. Exposure-outcome relationships were assessed in women and men, adjusting for potential confounders by multiple regression. In both sexes, moderate to heavy alcohol consumption (100+ g/week) was associated with 1.7-fold increased odds of elevated gamma-GT (>50 IU/L) in reference to nonsmoking alcohol abstainers, whereas smoking by itself was unrelated to gamma-GT. However, when moderate to heavy alcohol consumption was present in combination with heavy smoking, the odds ratios (95% CI) increased to 2.9 (1.1-7.6) in women and to 3.8 (2.2-6.6) in men (test for interaction between alcohol consumption and smoking: P(females) = 0.12, P(males) = 0.0017).

CONCLUSION

Our results support the notion of a detrimental interaction between cigarette smoking and alcohol consumption as determinants of elevated serum gamma-GT, especially in men.

Chronic Smoking Is Associated With Differential Neurocognitive Recovery in Abstinent Alcoholic Patients: A Preliminary Investigation

BACKGROUND

Approximately 50 to 90% of individuals in North America seeking treatment for alcoholism are chronic smokers. A growing body of evidence suggests that chronic cigarette smokers show a pattern of neurocognitive dysfunction similar to that observed in alcoholic patients. However, previous studies investigating neurocognitive recovery in abstinent alcoholic patients did not specifically consider the potential effects of chronic cigarette smoking.

METHODS

This study comprehensively compared longitudinal neurocognitive changes over 6 to 9 months of abstinence among 13 nonsmoking recovering alcoholic patients (ALC) and 12 actively smoking ALC. The neurocognitive performance of the alcoholic groups was compared with nonsmoking light-drinking controls (nonsmoking LD).

RESULTS

Nonsmoking ALC exhibited a significantly greater magnitude of longitudinal improvement than smoking ALC on measures of cognitive efficiency, executive skills, visuospatial skills, and working memory. Both nonsmoking ALC and smoking ALC demonstrated equivalent improvement on auditory-verbal learning, auditory-verbal memory, and processing speed. Nonsmoking LD showed no significant changes in neurocognition over time. In cross-sectional comparisons at 6 to 9 months of abstinence, nonsmoking ALC were superior to smoking ALC on measures of auditory-verbal learning, auditory-verbal memory, cognitive efficiency, executive skills, processing speed, and working memory. The longitudinal and cross-sectional neurocognitive differences observed between nonsmoking and smoking ALC remained significant after covarying for group differences in education, estimated premorbid intelligence alcohol consumption, and other potentially confounding variables. In smoking ALC, greater smoking severity was inversely related to longitudinal improvement on multiple neurocognitive measures.

CONCLUSIONS

These preliminary results suggest that chronic smoking may modulate neurocognitive recovery in abstinent alcoholic patients. More generally, chronic smoking may impact neurocognition in other conditions where is it a prevalent behavior.

The validity of the laboratory marker combinations DOVER and QUVER to detect physician's diagnosis of at-risk drinking

Especially in situations where it might be favorable for the patient to dissimulate the existing alcohol problem, 'objective' laboratory tests can be helpful. In this study we report validation of the two combinations DOVER (DOctor VERified) and QUVER (QUestionnarie VERified) of the biological markers percent carbohydrate-deficient transferrin (%CDT) and gamma-glutamyl-transferase (gamma-GT) to detect patients that have been identified by their physicians with at-risk drinking behavior. Fifty-eight general practitioners (GPs) participated at two study sites in South-West Germany. Patients filled in a questionnaire that included the alcohol use disorders identification test (AUDIT) and gave a blood sample. The GP recorded his/her assessment about the presence of an alcohol-related disorder in the patient. Receiver operating characteristics (ROC) analyses of the marker combinations DOVER and QUVER were performed. A total of 2940 patients participated in the study, of which 2496 completed data sets that could be used for further analysis. The area under the curve (AUC) of 79.5% for DOVER and 77.2% (QUVER) are in a higher range than the values for gamma%CDT (75.7%) or gamma-GT (72.5%) and %CDT (64.5%) and suggest superiority of the proposed marker combinations. Cross-validation results were almost identical with 76.6% and 73.3% for DOVER and QUVER, respectively. Our analysis demonstrated that the combination of the markers gamma-GT and %CDT with the physician's judgement of the condition as reference was superior to the use of single markers.

DOVER and QUVER-new marker combinations to detect and monitor at-risk drinking

BACKGROUND

At-risk drinking is a common medical problem. "Objective" laboratory tests are widely used, especially in situations where it might be favorable for the patient to dissimulate the existing alcohol problem. In this study, we report a new approach to combine the biological markers % carbohydrate-deficient transferrin (%CDT) and gamma-glutamyltransferase (gammaGT) to increase diagnostic properties to identify patients with at-risk drinking behavior.

METHODS

Fifty-eight general practitioners (GPs) participated in the study at 2 study sites in South-West Germany. Patients filled in a questionnaire that included the Alcohol Use Disorders Identification Test (AUDIT) and gave a blood sample. The GP recorded his assessment about the presence of an alcohol-related disorder in the patient. Screening results of 1 test center were used as a calculation sample. The results at the other site were used to cross-validate the study outcomes. The markers were combined by 2 methods. The first approach used the AUDIT (QUestionnaire VERified; QUVER), and the second was performed using the clinical judgment of the treating GP (DOctor VERified; DOVER). The formulas were calculated using linear and logistic regression models, respectively.

RESULTS

A total of 2,940 patients participated in the study, of whom 2,496 completed data sets that could be used for further analysis. In the receiver-operating characteristics (ROC) curves with the reference standard of an AUDIT> or =8, the area under the curve (AUC) of 78.8% for DOVER and 80.6% (QUVER) are in a higher range than the values for gamma-%CDT (75.4%) or gamma-GT (66.3%) and %CDT (74.3%) and suggest a clear superiority of the proposed marker combinations. Regarding the combinations DOVER and QUVER, the cross-validation results were almost identical, with 78.4/78.8% and 80.6/79.5%, respectively.

CONCLUSION

Our study is to date the largest practice-based trial that examines the value of the markers CDT and gamma-GT and their combinations for the screening of at-risk drinking in general practice under routine conditions. Our ROC analysis clearly demonstrated that the combination of the markers gamma-GT and %CDT under routine conditions with a behaviorally oriented reference standard leads to an improvement of diagnostic performance, more so than the use of single markers.

Biomarkers in alcoholism

Alcoholism ranks as one of the main current threats to the health and safety of people in most Western countries. Therefore, a high priority should be given to aims at reducing its prevalence through more effective diagnosis and early intervention. The need for objective methods for revealing alcohol abuse in its early phase has also been widely acknowledged. It is postulated here that the diagnosis of alcohol use disorders could be markedly improved by a more systematic use of specific questionnaires and laboratory tests, including blood ethanol, serum gamma-glutamyltransferase (GGT), carbohydrate-deficient transferrin (CDT), and mean corpuscular volume of erythrocytes (MCV). Recent research has provided new insights into the relationships between ethanol intake, biomarkers, and factors affecting their diagnostic validation, including gender, age, and the effects of moderate drinking and obesity. It appears that the concept of reference intervals for several ethanol-sensitive parameters in laboratory medicine needs to be revisited. CDT is currently the most specific marker of alcohol abuse, and when combined with GGT using a mathematically formulated equation a high sensitivity is reached without loss of assay specificity. Possible new biomarkers include minor ethanol metabolites (protein-acetaldehyde condensates and associated autoimmune responses, ethylglucuronide, and phosphatidylethanolamine), 5-hydroxytryptophol, and genetic markers although so far their routine applications have been limited.

Laboratory Markers Carbohydrate-Deficient Transferrin, γ-Glutamyltransferase, and Mean Corpuscular Volume Are Not Useful as Screening Tools for High-Risk Drinking in the General Population: Results From the Study of Health in Pomerania (SHIP)

BACKGROUND

Assessment of high-risk drinking in the general population can be problematic: questionnaire-based instruments may carry the problem of random or systematic recall bias, and the effectiveness of screening of single biomarkers has been shown to be insufficient. In this article, we analyze the alcohol intake/biomarker relationship of carbohydrate-deficient transferrin (CDT), gamma-glutamyltransferase (GGT), and erythrocyte mean corpuscular volume (MCV). Specific aims were (1) screening effectiveness comparison of GGT, CDT, and MCV in terms of sensitivity, specificity, and positive (PPVs) and negative predictive values (NPVs) and the effect of covariates on these measures; (2) the comparison of summary measures for the effectiveness of screening: the receiver characteristic curve (ROC) and the area under the ROC; and (3) to answer the question of which covariates effect which biomarkers and whether accounting for relevant covariates increases the prognostic value of biomarkers to levels that allow for application in the general population.

METHODS

In a representative cross-sectional health survey in northeast Germany with data collection from 1997 to 2001, 4310 men and women were asked for their recent alcohol consumption and smoking. Biomarkers were analyzed from blood samples. The effectiveness of screening of CDT, GGT, and MCV for high-risk drinking (men: >60 g/day, women: >40 g/day) was analyzed with PPV and ROC curve analysis.

RESULTS

For all three biomarkers, PPVs for high-risk drinking are very low (< 50%). There are some effects of covariates on screening effectiveness and on PPV, and knowledge of these covariates increases screening effectiveness, but no subgroup that had a combination of covariate levels and prevalence of high-risk drinking that led to a PPV > 50% could be found.

CONCLUSIONS

: Accounting for covariates in the screening procedure does not lead to a sufficient increase in PPV. Screening effectiveness of laboratory markers CDT, GGT, and MCV is insufficient for their application as screening tools for high-risk alcohol drinking in the general population. This was found using self-reported alcohol consumption as an imperfect gold standard, which is a limitation of the study, although self-reports are the standard instrument in comparable epidemiologic studies.

PHosphatidylethanol (PEth) concentrations in blood are correlated to reported alcohol intake in alcohol-dependent patients

AIMS

Phosphatidylethanol (PEth) is an abnormal phospholipid formed only in the presence of ethanol by the enzyme phospholipase D. PEth in blood is a promising new marker for ethanol abuse. None of the biological markers used at the present time is sensitive and specific enough for the diagnosis of alcoholism.

METHODS

The most frequently used alcohol markers [carbohydrate deficient transferrin (CDT), gamma-glutamyltransferase (GGT), and mean corpuscular volume (MCV)] were studied together with PEth in actively drinking alcohol-dependent patients (inpatients and outpatients), with regard to correlation to ethanol intake and diagnostic sensitivity of the markers. The relation between the markers was also studied.

RESULTS

PEth, CDT, and GGT correlated to ethanol intake, with the strongest correlation found for PEth. The diagnostic sensitivity for PEth was 99%, and for other markers it varied between 40 and 77%. Only when CDT was combined with GGT was a sensitivity of 94% reached. PEth correlated to CDT and GGT but not to MCV. CDT did not correlate to GGT or MCV.

CONCLUSIONS

Blood concentrations of PEth are highly correlated to ethanol intake, and the present results indicate that its diagnostic sensitivity is higher than that for previously established alcohol markers.

Body fat distribution, liver enzymes, and risk of hypertension: evidence from the Western New York Study

Gamma-glutamyltransferase (GGT) has been associated with hypertension (HTN); however, the nature of this association remains unclear. GGT is a marker of alcohol consumption, but it is also related to the infiltration of fat in the liver (fatty liver). The association between GGT and HTN was examined in a 6-year longitudinal investigation among 1455 men and women who returned for the follow-up visit. Baseline variables included serum GGT, blood pressure, and anthropometric measures. Incident HTN was defined as blood pressure > or =140/90 or on antihypertensive medication at the follow-up visit. To eliminate individuals with potential liver pathology, analyses focused only on individuals with GGT within its normal range (n=897). Participants were divided in quintiles (Q) based on their baseline GGT levels. Multiple logistic regression analyses [odds ratio (95% confidence intervals)] revealed a significant association of GGT with incident hypertension [2.1 (1.1 to 4.0) Q5 versus Q1]. In subgroup analyses, GGT and HTN were significantly associated among both noncurrent and current drinkers, but only for participants above the median of anthropometric measures [eg, body mass index >26.4, 2.3 (0.9 to 5.7), waist circumference >86.1 cm, 3.7 (1.4 to 9.9), and abdominal height >19.8 cm, 3.1 (1.2 to 8.5), for Q5 versus Q1, in fully adjusted models]. These findings suggest that the association between GGT and hypertension is not caused solely by alcohol consumption and indicate that serum GGT, within its normal range, may predict hypertension among individuals with increased central fat distribution, suggesting that fatty liver may represent an important underlying mechanism for this association.

Differential effects of alcohol drinking pattern on liver enzymes in men and women

BACKGROUND

Increasing evidence suggests that drinking pattern may have powerful implications for health; however, very few studies have focused on the association between drinking pattern and risk of alcoholic liver damage. This study was aimed at examining the association of gamma-glutamyltransferase (GGT), aspartate aminotransferase, and alanine aminotransferase with current alcohol consumption and with some aspects of drinking pattern (e.g., drinking frequency during the week and in relation to food consumption).

METHODS

A cross-sectional analysis was conducted of a random sample of 2943 white residents of Erie and Niagara Counties in New York State who were 35 to 80 years of age and free from known hepatic disease.

RESULTS

The most significant associations were found for GGT; in both sexes, average levels were significantly higher in current and former drinkers compared with lifetime abstainers. In analyses based on quartiles of alcohol consumption, only participants in the two top quartiles showed significantly elevated enzymes compared with both lifetime abstainers and participants in other quartiles. For drinking pattern, there was evidence of sex-specific associations. In men, daily drinkers showed the highest levels of GGT, whereas in women, the highest level of GGT was observed in weekend drinkers. Women (but not men) who consumed alcohol without food exhibited higher levels of GGT compared with women who consumed alcoholic beverages in relation to food.

CONCLUSIONS

These findings support the hypothesis that, in addition to amount, drinking pattern may affect liver function and that differences exist between sexes with regard to the effect of drinking pattern on liver function and potential liver damage.

Carbohydrate-deficient transferrin (CDT)--a biomarker for long-term alcohol consumption

Carbohydrate-deficient transferrin (CDT) is a biomarker for chronic alcohol intake of more than 60 g ethanol/d. It has been reported to be superior to conventional markers like gamma-glutamyltransferase (GGT) and mean corpuscular volume MCV). This review covers theoretical and analytical aspects, with data from controlled drinking experiments and from different population subgroups such as subjects with different liver diseases or different drinking patterns. CDT determinations are particularly indicated in (1) cases of chronic alcohol consumption and relapses after withdrawal, (2) license reapplication after driving under alcohol influence, (3) differentiating patients with enzyme-inducing medication from those with alcohol abuse, 4) congenital disorders of glycosylation such as carbohydrate-deficient glycoprotein syndrome Ia (CDGS Ia), and (5) patients treated for galactosemia. The main advantage of CDT is its high specificity, as evidenced in combination with increased alcohol consumption. CDT values are not markedly influenced by medication except in immunosuppressed patients, who may show low CDT values. In general, CDT values appear less elevated after alcohol intake in women. The main disadvantage is the relatively low sensitivity. Hence, this parameter is not suitable for screening for subjects with alcohol abuse in the general population. As CDT, GGT, and MCV are connected with chronic alcohol consumption by different pathophysiological mechanisms, a combination of these parameters will further improve the diagnostic value.

Role of high normal gamma-glutamyltransferase level in identifying heavy alcohol use in young men

The objective of the current study was to determine the predictive value of high normal gamma-glutamyltransferase (GGT) level as an indication of heavy drinking in young men. In a sample of 577 men attending a one-day army recruitment process mandatory for all Swiss men at age 19 years, GGT level was evaluated as the dependent variable for each of eight dichotomous classifications of individuals on the basis of meeting cut-off criteria for five indexes of alcohol use, two indexes of alcohol-related problems, and one index of body mass. The sensitivity, specificity, and predictive values of GGT level in identifying subjects as either heavy drinkers or being overweight were determined. Compared with findings for their counterparts, GGT level was higher in subjects reporting consumption of more than 14 drinks per week (20.5 +/- 7.81 vs. 18.9 +/- 7.60, P <.05), in those reporting being drunk at least once during the past 30 days (20.3 +/- 7.80 vs. 18.3 +/- 7.43, P <.001), and in individuals with body mass indexes >or=25 kg/m(2) (25.8 +/- 10.84 vs. 18.3 +/- 6.59, P <.001). At a GGT level cut-off of 20 U/l, the sensitivity, specificity, and positive and negative predictive values of either being a heavy drinker or overweight were 48.2%, 70.2%, 67.7%, and 51.2%, respectively. Exclusion of subjects with body mass indexes of >or=25 kg/m(2) revealed similar results. High normal GGT level in young men is indicative of heavy alcohol use or being overweight; when present, subjects should be screened further for potential concomitant drinking problems.

Effects of Alcohol Consumption on Hepatocellular Injury in Japanese Men

To clarify the effects of alcohol consumption on hepatocellular injury, we examined aspartate and alanine aminotransferases (AST and ALT), and gamma-glutamyltransferase (GGT), together with weekly alcohol consumption calculated from a self-rating questionnaire, in 1113 Japanese salesmen. The thresholds of associations between alcohol consumption and liver markers were estimated by the benchmark dose (BMD) method. The AST, ALT and GGT were positively correlated with alcohol intake (p<0.001), as well as age and body mass index (BMI); the relations to alcohol were statistically significant even when controlling for age, BMI and smoking habit. Although the AST and GGT were associated with four types of alcoholic beverage (p<0.01), it was only whiskey that had close relation to the ALT (p<0.05). The thresholds of alcohol consumption (ethanol g/week), i.e., 95% lower confidence limits of the BMD, were 362 for AST, 660 for ALT, and 252 for GGT. The thresholds for GGT and AST in Japanese men seem to be somewhat higher than those reported in Western countries. It is suggested that hepatocellular injury (i.e., AST elevation) in Japanese men may emerge at the ethanol level of more than 50 g/day.

Use of biomarkers for alcohol use disorders in clinical practice

BACKGROUND

Biomedical markers may provide additive objective information in screening and confirmation of acute or recent consumption, intoxication, relapse, heavy drinking, hazardous/harmful use/abuse and dependence and alcohol use related organ dysfunction (alcohol use-related disorders: AUDs).

AIMS

To review the use of biomarkers in clinical practice to detect AUDs.

FINDINGS

About one-fifth of the patients seen in clinical practice have AUDs, which offer a variety of treatment options if diagnosed. The diagnosis of AUDs relies on clinical and alcohol-related history, physical examination, questionnaires and laboratory values. No clinical available laboratory test [e.g. for acute abuse: alcohol in blood or breath; for chronic alcohol abuse: gamma-glutamyl transferase (GGT), mean corpuscular volume (MCV), carbohydrate-deficient transferrin (CDT)] is reliable enough on its own to support a diagnosis of alcohol dependence, harmful use or abuse. Sensitivities, specificities and the predictive values may vary considerably according to patient and control group characteristics (e.g. gender, age or related comorbidity). In patient groups with limited cooperation markers may be helpful when considering treatment options.

CONCLUSIONS

More research is needed to determine the value of markers (single or combined, with questionnaires) in the context of clinical decision-making algorithms in defined settings and with defined dichotomous outcome variables.

Traditional markers of excessive alcohol use

AIMS

The blood tests used traditionally as markers of excessive drinking are the liver enzymes, gamma glutamyltransferase (GGT), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and the red blood cell volume (mean corpuscular volume: MCV). Here we review the nature of these markers' association with alcohol use, their practical application in detecting, assessing or monitoring drinking and increases in understanding of these markers in the past 10 years.

DESIGN

Articles were identified via Medline search and perusal of bibliographies.

FINDINGS

The conventional markers have imperfect sensitivity and specificity, but have an added clinical role in the detection of complications of drinking, and of comorbid conditions that may increase risk of drinking. GGT may in part be a marker of the oxidative stress associated with ethanol metabolism. Markers are more likely to be elevated in those aged more than 30 years and in regular drinkers with a longer drinking history. The markers may be useful in opportunistic case finding, in motivating patients to change drinking and in monitoring treatment response. Increased prevalence of obesity and hepatitis C must be considered in interpretation of liver enzyme results. The liver enzymes are prognostic indicators for several medical conditions and for mortality.

CONCLUSIONS

These conventional tests are widely available and relatively inexpensive. While having limited sensitivity and specificity in detection of excessive drinking, they also provide valuable data on complications of drinking, comorbid conditions that may be affected by drinking and, in some cases, prognosis.

Value of determining carbohydrate-deficient transferrin isoforms in the diagnosis of alcoholic liver disease

OBJECTIVE

To determine whether isoform separation of carbohydrate-deficient transferrin (CDT) is of value in the diagnosis of alcoholic liver disease (ALD) and is specific to ALD when compared with other liver diseases.

PATIENTS AND METHODS

During 1995 and 1996, 47 patients with ALD were evaluated with CDT at the Mayo Clinic in Rochester, Minn. The diagnosis of ALD was based on biochemical and histological analyses and on a history of drinking that exceeded 5 years with an average alcohol intake of more than 60 g/d. Disease controls included nonalcoholic steatohepatitis (NASH) (n = 26) and other liver disease (n = 22). Normal controls (n = 21) were healthy individuals without liver disease. Transferrin isoforms were quantified by densitometry of Coomassie-stained transferrins after affinity purification and isoelectric focusing. The pentasialo, tetrasialo, trisialo, disialo, monosialo, and asialo isoforms were quantified as percentages of total band densities.

RESULTS

Receiver operating characteristic (ROC) curves were constructed for each isoform. The curves for total desialated isoforms (sum of disialo, monosialo, and asialo) displayed the best relationship between sensitivity and specificity with an ROC-area under the curve (AUC) of 0.922. The ROC-AUC values for individual transferrin isoforms in ALD vs NASH for pentasialo, tetrasialo, trisialo, disialo, monosialo, and asialo were 0.806, 0.917, 0.885, 0.933, 0.804, and 0.785, respectively. Only 58% of patients with ALD were detected at a specificity that excluded ALD in 84% of those who did not have it.

CONCLUSION

Within alcohol ingestion times reported to us, no associations with recent drinking were observed. Alcohol as a cause of liver disease is not perfectly established by CDT analysis, although a high total CDT value favors ALD over NASH.

Biochemical markers of alcohol use in pregnant women

OBJECTIVES

To describe the serious health consequences of alcohol (ethanol) use, especially as they relate to pregnancy and the development of fetal alcohol syndrome (FAS) and fetal alcohol effects (FAE). The classic markers of alcohol exposure, including blood/breath alcohol, gamma-glutamyl transferase (gammaGT), mean corpuscular volume (MCV), hemoglobin-associated acetaldehyde (HAA) and carbohydrate deficient transferrin (CDT), are valuable and their methods of analysis are reviewed.

CONCLUSIONS

Since both FAS and FAE represent two of the leading preventable causes of mental retardation and birth defects, identification of alcohol use early in pregnancy is important to avoid adverse fetal outcomes. Unfortunately, the diagnosis of FAS and FAE is usually made after birth, when alcohol damage has become irreversible and permanent. The clinical laboratory can help prevent this damage and make a valuable contribution in assessing prenatal alcohol use. The clinical utility of blood/breath alcohol, gammaGT, MCV, HAA and CDT in alcohol use identification, especially in pregnancy, is substantial. Although none of the markers singularly has adequate sensitivity and specificity for screening, their diagnostic utility increases when measured as a panel. This is especially true in detecting alcohol use in pregnancy where the presence of several positive markers was correlated with the presence of alcohol-related fetal effects.