Carbohydrate-deficient transferrin as a measure of immoderate drinking: remaining issues

Blood Biomarkers of Alcohol Use: A Scoping Review

Purpose of Review

Understanding whether a person has consumed alcohol or not, as well as quantitative assessment of alcohol use, are often based on self-reported measures, which may be subject to recall bias, among other challenges. Although not without limitations, blood biomarkers may complement self-reported assessments to provide a more accurate determination of the presence and quantity of alcohol use. The aim of this review is to provide a critical overview of the current knowledge and research on biomarkers of alcohol use, with a particular focus on blood tests.

Recent Findings

This scoping review summarizes the published work on blood tests currently used in clinical practice, including phosphatidyl ethanol (PEth), fatty acid ethyl ester (FAEE), carbohydrate-deficient transferrin (CDT), total serum sialic acid (TSA), mean corpuscular volume (MCV), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyl transpeptidase (GGT), and cholesteryl ester transfer protein (CETP). Emerging blood biomarkers with a potential use to assess alcohol drinking are also briefly reviewed, including N-Acetyl-β-Hexosaminidase (Beta-Hex), macrophage migration inhibitory factor (MIF), and D-dopachrome tautomerase (DDT). We discuss the aforementioned biomarkers in the context of their clinical implications, characteristics, strengths, and limitations.

Summary

The available blood biomarkers considerably vary in the time period in which they detect alcohol use and the amount of alcohol they are sensitive to. While currently available biomarkers provide useful information, especially in combination with self-reported measures, future work is needed to identify more sensitive and specific blood biomarkers for different levels and patterns of alcohol use. Integration of such biomarkers into clinical practice and research will increase the accuracy and richness of the data and may guide more effective and targeted strategies for prevention, diagnosis, and treatment of excessive alcohol use.

Detection and Quantification of Carbohydrate-Deficient Transferrin by MALDI-Compatible Protein Chips Prepared by Ambient Ion Soft Landing

BACKGROUND

Transferrin is synthetized in the liver and is the most important iron-transport carrier in the human body. Severe alcohol consumption leads to alterations in glycosylation of transferrin. Mass spectrometry can provide fast detection and quantification of transferrin isoforms because they have different molecular masses. In this study, we used antibody chips in combination with MALDI-TOF MS for the detection and quantification of transferrin isoforms.

METHODS

Protein chips were prepared by functionalization of indium tin oxide glass using ambient ion soft landing of electrosprayed antitransferrin antibody. Two microliters of patient serum was applied on the antibody-modified spots, and after incubation, washing, and matrix deposition, transferrin isoforms were detected by MALDI-TOF MS. Peak intensities of each transferrin form were used to calculate total carbohydrate-deficient transferrin (CDT). The CDT values obtained by the MALDI chip method were compared with the results obtained by a standard capillary electrophoresis (CE).

RESULTS

The chip-based MALDI-TOF MS method was used for enrichment and detection of CDT from human serum. A sample cohort from 186 patients was analyzed. Of these samples, 44 were positively identified as belonging to alcoholic patients, whereas 142 were negative by the MALDI chip approach. The correlation of the data obtained by the CE and the chip-based MALDI was r = 0.986, 95% CI.

CONCLUSIONS

Functionalized MALDI chips modified by antitransferrin antibody prepared by ambient ion soft landing were successfully used for detection and quantification of CDT from human sera.

Proteoform Analysis to Fulfill Unmet Clinical Needs and Reach Global Standardization of Protein Measurands in Clinical Chemistry Proteomics

In clinical testing of protein markers, structure variants of the measurand are often not taken into account. This heterogeneous character of protein measurands in immunoassays often renders test standardization impossible. Consequently, test results from different methods can lead to underdiagnosis or overdiagnosis and, thus, undertreatment or overtreatment of patients. The systematic structural analysis of protein isoforms has been coined proteoform profiling and is performed through mass spectrometry-based proteomics strategies. Knowledge on proteoforms allows refining existing uni-marker tests and moreover has great potential to contribute to the urgent need for new tests to predict prognosis and severity of diseases.

High-resolution mass spectrometry glycoprofiling of intact transferrin for diagnosis and subtype identification in the congenital disorders of glycosylation

Diagnostic screening of the congenital disorders of glycosylation (CDG) generally involves isoelectric focusing of plasma transferrin, a robust method easily integrated in medical laboratories. Structural information is needed as the next step, as required for the challenging classification of Golgi glycosylation defects (CDG-II). Here, we present the use of high-resolution nano liquid chromatography-chip (C8)-quadrupole time of flight mass spectrometry (nanoLC-chip [C8]-QTOF MS) for protein-specific glycoprofiling of intact transferrin, which allows screening and direct diagnosis of a number of CDG-II defects. Transferrin was immunopurified from 10 μL of plasma and analyzed by nanoLC-chip-QTOF MS. Charge distribution raw data were deconvoluted by Mass Hunter software to reconstructed mass spectra. Plasma samples were processed from controls (n = 56), patients with known defects (n = 30), and patients with secondary (n = 6) or unsolved (n = 3) cause of abnormal glycosylation. This fast and robust method, established for CDG diagnostics, requires only 2 hours analysis time, including sample preparation and analysis. For CDG-I patients, the characteristic loss of complete N-glycans could be detected with high sensitivity. Known CDG-II defects (phosphoglucomutase 1 [PGM1-CDG], mannosyl (α-1,6-)-glycoprotein β-1,2-N-acetylglucosaminyltransferase [MGAT2-CDG], β-1,4-galactosyltransferase 1 [B4GALT1-CDG], CMP-sialic acid transporter [SLC35A1-CDG], UDP-galactose transporter [SLC35A2-CDG] and mannosyl-oligosaccharide 1,2-alpha-mannosidase [MAN1B1-CDG]) resulted in characteristic diagnostic profiles. Moreover, in the group of Golgi trafficking defects and unsolved CDG-II patients, distinct profiles were observed, which facilitate identification of the specific CDG subtype. The established QTOF method affords high sensitivity and resolution for the detection of complete glycan loss and structural assignment of truncated glycans in a single assay. The speed and robustness allow its clinical diagnostic application as a first step in the diagnostic procedure for CDG defects.

Early adolescent symptoms of social phobia prospectively predict alcohol use

OBJECTIVE

The current study examined whether social phobia (SP) symptoms in early adolescence prospectively predicted alcohol use through middle adolescence in a community sample of youth.

METHOD

Data from an ongoing longitudinal study (N = 277) of mechanisms of HIV-related risk behaviors in youth were used to assess the extent to which SP symptoms in early adolescence (mean [SD] age = 11.00 years [0.81]) would predict alcohol use across five annual assessment waves. Adolescents completed measures of SP symptoms, depressive symptoms, and alcohol use at each wave.

RESULTS

Higher SP symptoms at baseline predicted higher average odds of alcohol consumption during subsequent waves but did not significantly predict an increase in the odds of alcohol use as a function of time. Within a lagged model, SP symptoms measured at a prior assessment point (1 year earlier) predicted greater odds of drinking alcohol at the following assessment point. Importantly, alcohol use did not significantly predict SP symptoms over time. These results suggest that early SP symptoms are an important risk factor for increased odds of subsequent alcohol use.

CONCLUSIONS

The present findings highlight that elevated SP symptoms place adolescents at risk for early alcohol use. Early interventions targeting SP symptoms may be crucial for the prevention of problematic alcohol use in early to mid-adolescence. Implications for prevention and treatment approaches are discussed.

Determination of carbohydrate-deficient transferrin in a Han Chinese population

Background

Carbohydrate-deficient transferrin (CDT) is a widely used alcohol biomarker. Because of the high prevalence of chronic alcohol abuse in many countries, CDT plays an important role in the areas of traffic, clinical, and forensic medicine. However, CDT levels have not been determined in the Han Chinese population. Therefore, we investigated the frequency of genetic transferrin variants and the relationship between CDT levels and alcohol consumption in this population. From this data, we established a CDT cut-off for Han Chinese and evaluated the analytical performance of the CDT capillary zone electrophoresis system.

Results

The prevalence of transferrin variants was 4.14%. The mean CDT level of the reference group was 0.73%. We recommended CDT level >1.5% as cut off standard of alcohol intake to ensuring the specificity was best. The CDT test total precision for 0.5%, 0.7%, and 1.55% was 14.4%, 11.5%, and 7.2%, respectively. The data showed good linearity in the studied range of 0.6% to 8.2%.

Conclusions

These results demonstrate that CDT is a useful marker to detect heavy daily alcohol consumption. We proposed and evaluated the first CDT cut-off for the Han Chinese population, and we showed that the CDT capillary zone electrophoresis system is a reliable analytic method.

Discrepancy between how children perceive their own alcohol risk and how they perceive alcohol risk for other children longitudinally predicts alcohol use

This paper examined discrepancies between children's self-perceptions of the riskiness of alcohol use versus their perceptions of the riskiness of alcohol use for other children, and whether these discrepancies predicted children's future alcohol use. Participants included 234 children (M=11 years, 45.3% female) who completed baseline and one-year follow-up assessments on self-perceived riskiness of alcohol use, perceived riskiness of alcohol use for other same-age children, and own past year alcohol use. When considering child age and gender, baseline alcohol use, and the individual reports of the riskiness of alcohol use, the interaction between alcohol use riskiness reports prospectively predicted greater odds of alcohol use. The highest percentage of childhood alcohol use at one-year follow-up came from those children with both low self-perceived riskiness of alcohol use and high perceived riskiness of alcohol use for other children. Children's perceptions of multiple people's risk from alcohol use result in identifying important subgroups of children at risk for early-onset alcohol use.

Changes in sensation seeking and risk-taking propensity predict increases in alcohol use among early adolescents

BACKGROUND

Conceptual models implicating disinhibitory traits often are applied to understanding emergent alcohol use, but, little is known of how inter-individual changes in these constructs relate to increases in alcohol use in early adolescence. The current study utilized behavioral and self-report instruments to capture the disinhibitory-based constructs of sensation seeking and risk-taking propensity to examine if increases in these constructs over time related to increases in early adolescent alcohol use.

METHODS

Participants included a community sample of 257 early adolescents (aged 9 to 12) who completed a self-report measure of sensation seeking, a behavioral task assessing risk-taking propensity, and a self-report of past year alcohol use, at 3 annual assessment waves.

RESULTS

Both sensation seeking and risk-taking propensity demonstrated significant increases over time, with additional evidence that change in the behavioral measure of risk-taking propensity was not because of practice effects. Greater sensation seeking and greater risk-taking propensity demonstrated concurrent relationships with past year alcohol use at each assessment wave. Prospective analyses indicated that after accounting for initial levels of alcohol use, sensation seeking, and risk-taking propensity at the first assessment wave, larger increases in both constructs predicted greater odds of alcohol use at subsequent assessment waves.

CONCLUSIONS

Results indicate the role of individual changes in disinhibitory traits in initial alcohol use in early adolescents. Specifically, findings suggest it is not simply initial levels of sensation seeking and risk-taking propensity that contribute to subsequent alcohol use but in particular increases in each of these constructs that predict greater odds of use. Future work should continue to assess the development of sensation seeking and risk-taking propensity in early adolescence and target these constructs in interventions as a potential means to reduce adolescent alcohol use.

Alcohol Pathophysiology

There is no specialized alcohol addiction area in the brain; rather, alcohol acts on a wide range of excitatory and inhibitory nervous networks to modulate neurotransmitters actions by binding with and altering the function of specific proteins. With no hemato-encephalic barrier for alcohol, its actions are strongly related to the amount of intake. Heavy alcohol intake is associated with both structural and functional changes in the central nervous system with long-term neuronal adaptive changes contributing to the phenomena of tolerance and withdrawal. The effects of alcohol on the function of neuronal networks are heterogeneous. Because ethanol affects neural activity in some brain sites but is without effect in others, its actions are analyzed in terms of integrated connectivities in the functional circuitry of neuronal networks, which are of particular interest because of the cognitive interactions discussed in the manuscripts contributing to this review. Recent molecular data are reviewed as a support for the other contributions dealing with cognitive disturbances related to alcohol acute and addicted consumption.

Comparison of the combined marker GGT-CDT and the conventional laboratory markers of alcohol abuse in heavy drinkers, moderate drinkers and abstainers

AIMS

A combined index based on gamma-glutamyltransferase (GGT) and carbohydrate-deficient transferrin (CDT) measurements (GGT-CDT) has been recently suggested to improve the detection of excessive ethanol consumption. The aim of this work was to compare GGT-CDT with the conventional markers of alcohol abuse in individuals with a wide variety of alcohol consumption.

METHODS

A cross-sectional and follow-up analysis was conducted in a sample of 165 heavy drinkers, consuming 40-540 g of ethanol per day, and 86 reference individuals who were either moderate drinkers (n = 51) or abstainers (n = 35).

RESULTS

GGT-CDT (5.35 +/- 1.08) in the heavy drinkers was significantly higher than in the reference individuals (3.30 +/- 0.37). The sensitivity of GGT-CDT (90%) in correctly classifying heavy drinkers exceeded that of CDT (63%), GGT (58%), mean corpuscular volume (MCV) (45%), aspartate aminotransferase (AST) (47%), and alanine aminotransferase (ALT) (50%), being also essentially similar for alcoholics with (93%) or without (88%) liver disease. When comparing the data using either moderate drinkers or abstainers as reference population, the sensitivity of GGT-CDT, CDT, and ALT remained unchanged whereas the sensitivity of GGT, MCV, and AST was found to show variation.

CONCLUSIONS

GGT-CDT improves the sensitivity of detecting excessive ethanol consumption as compared with the traditional markers of ethanol consumption. These findings should be considered in the assessment of patients with alcohol use disorders.

Validity of carbohydrate-deficient transferrin (%CDT), gamma-glutamyltransferase (gamma-GT) and mean corpuscular erythrocyte volume (MCV) as biomarkers for chronic alcohol abuse: a study in patients with alcohol dependence and liver disorders of non-alcoholic and alcoholic origin

AIM

To test the clinical performance of carbohydrate-deficient transferrin (%CDT), gamma-glutamyltransferase (gamma-GT) and mean corpuscular erythrocyte volume (MCV) as biomarkers for alcoholism with a special focus on patients suffering from liver diseases.

DESIGN

Well-characterized collectives of alcohol-dependent patients with current consumption (ALC patients, n = 101), and relevant control groups (115 social drinkers, 46 patients with unspecifically increased gamma-GT, 51 hepatitis patients and 20/31 patients with non-alcohol/alcohol-dependent liver cirrhosis) were included into the study. The Positive Alcohol Use Disorders Test (AUDIT) score, International Classification of Diseases version 10 (ICD-10)/Diagnostic and Statistical Manual version IV (DSM-IV) criteria and blood drawn within 4 days of last drinking were inclusion criteria for subjects with regular heavy drinking. %CDT was determined using an automated assay which recently had been completely modified.

FINDINGS

Median AUDIT scores of patients without/with regular heavy drinking were 1-3/27. The following medians/95th percentiles were obtained for %CDT: social drinkers 2.2/3.0, patients with unspecifically increased gamma-GT 2.1/3.0, hepatitis 2.0/4.4, non-alcohol-dependent liver cirrhosis 2.4/4.8, alcohol-dependent liver cirrhosis 3.0/5.9, ALC patients 3.9/14.9. Differences between patients without and with alcohol abuse were highly significant (P < 0.001). No differences in CDT values were found between males and females. There was no correlation between %CDT values, gamma-GT, MCV and the amount of alcohol consumed in ALC patients; 3.0%CDT (95th percentile social drinkers) is proposed as cut-off for the test used (Tina-quant %CDT 2nd-generation). At this cut-off, the sensitivity for ALC patients was 73.3%, whereas gamma-GT/MCV had a sensitivity of 71.3%/64.4%. Multivariate analysis performed at 95% specificity resulted in an improvement of the sensitivity by combining %CDT with gamma-GT (83.2%). A further enhancement of the sensitivity to 88.1% was obtained by combination of %CDT, gamma-GT and MCV. The diagnostic specificity of %CDT calculated at the cut-off of 3% was 93.5% in patients with unspecifically increased gamma-GT, 88.2% in hepatitis patients and 70.0% in patients with non-alcohol-dependent liver cirrhosis. %CDT was more specific in these patient collectives than MCV, and especially more than gamma-GT (specificity in hepatitis 52.9%, and 35.0% in non-alcohol-dependent liver cirrhosis).

CONCLUSION

%CDT is of high diagnostic value to support diagnosis of alcohol-use disorders. The specificity of this marker in patient groups with liver disorders is superior to the biomarkers gamma-GT and MCV.

Biomarkers of alcohol consumption in patients classified according to the degree of liver disease severity

OBJECTIVE

In the search for optimal biomarkers of excessive drinking, only a few studies have been conducted to compare the relationships between ethanol consumption, liver status, and various laboratory markers of ethanol-induced diseases.

MATERIAL AND METHODS

Concentrations of carbohydrate-deficient transferrin (%CDT and CDTect methods), serum sialic acid (SA), gamma-glutamyl transferase (gamma-GT), aspartate aminotransferase (ASAT), mean corpuscular volume (MCV), and a marker of fibrogenesis (PIIINP) were studied in 102 alcoholics with (n=59) or without (n=43) alcoholic liver disease. Controls were 34 healthy volunteers who were either social drinkers or abstainers.

RESULTS

Although concentrations of all markers were significantly higher in the alcoholic patients than in the healthy controls, their diagnostic characteristics showed a considerable degree of variation. The %CDT, SA, and MCV showed the strongest correlations with the amount of recent alcohol intake. The presence of liver pathology notably influenced the results of CDTect, GT, ASAT, and PIIINP. In ROC analyses, the highest rates of diagnostic accuracy for detecting hazardous drinking were reached with GT (0.94), CDT (0.86), and SA (0.85), followed by MCV (0.79) and ASAT (0.77). Upon abstinence, the estimated times for normalization varied between 10 days (CDTect) and 25 days (GT).

CONCLUSIONS

Our data suggest distinct differences in the clinical characteristics of biological markers of ethanol consumption. While the overall accuracy of CDT and GT appear to be highest in the detection of problem drinking, serum SA and PIIINP measurements are of further value when the effects of liver pathology and ethanol drinking need to be differentiated.

A review of genetic, biological, pharmacological, and clinical factors that affect carbohydrate-deficient transferrin levels

BACKGROUND

Carbohydrate-deficient transferrin (CDT) is an alcohol biomarker recently approved by the U.S. Food and Drug Administration. This test is increasingly being used to detect and monitor alcohol use in a variety of health care, legal, and industrial settings. The goal of this study is to review the genetic, biological, pharmacological, and clinical factors that may affect CDT levels.

METHODS

A review of the literature identified 95 research articles that met the authors' criteria and reported potential interactions of a variety of factors on percent and total CDT levels. The review established 12 categories of variables that may affect CDT levels. These categories include (1) alcohol use, (2) genetic factors, (3) race, (4) gender, (5) age, (6) liver disease, (7) iron levels, (8) tobacco use, (9) medication such as estrogen and anticonvulsants, (10) metabolic factors such as body mass index and total body water, (11) chronic medical conditions such as rheumatoid arthritis, and (12) surgical patients.

RESULTS

There is evidence that %CDT levels are affected by alcohol use, end-stage liver disease, and genetic variants. In addition to these three factors, total CDT levels (CDTect) are also affected by factors that raise transferrin levels such as iron deficiency, chronic illnesses, and menopausal status. Other potential factors such as tobacco and age appear to be confounded by alcohol use. The roles of female gender, low body mass index, chronic inflammatory diseases, and medication on CDT levels require further study. False negatives are associated with female gender, episodic lower level alcohol use, and acute trauma with blood loss.

CONCLUSIONS

This review suggests that a number of factors are associated with false-positive CDTect and %CDT levels. CDT offers great promise to assist physicians in the care of patients to detect and monitor heavy alcohol use.

Prevalence of high alcohol and benzodiazepine consumption in sleep apnea patients studied with blood and urine tests

OBJECTIVE

To evaluate the prevalence of alcoholism and benzodiazepine abuse among patients with obstructive sleep apnea syndrome (OSAS). Such abuse may aggravate the tendency to apneas, especially in patients with OSAS.

MATERIAL AND METHODS

The study included 98 consecutive OSAS patients. Two patients dropped out; blood samples could not be obtained from two other patients and a urine sample could not be obtained from one. Blood and urine samples were examined for carbohydrate-deficient transferrin (CDT) and 5-hydroxytryptophol (5-HTOL), markers of excess alcohol intake, and urine-benzodiazepines (u-Benz), a marker of drug abuse. Patients with positive screening tests were offered therapy for their abuse.

RESULTS

The CDT test was positive in 8/94 patients (8.5%), the 5-HTOL test in 6/95 (6.3%) and the u-Benz test in 3/95 (3.2%).

CONCLUSIONS

Our findings correlate well with current views concerning alcohol and drug abuse in Sweden, and do not indicate that the frequency of such abuse is higher among OSAS patients. It should be noted that none of the patients who screened positive in the laboratory tests admitted to being alcohol or drug abusers when they consulted their physician. We recommend screening all OSAS patients for alcohol abuse using not only a questionnaire but also a laboratory test such as the CDT test.

Selection of a substance use disorder diagnostic instrument by the National Drug Abuse Treatment Clinical Trials Network

Several instruments for diagnosing substance use disorders (SUD) have been developed, but to date none has emerged as the standard for community-based clinical studies. To select the most suitable SUD diagnostic instrument for its clinical trials, the National Drug Abuse Treatment Clinical Trials Network (CTN) implemented a procedure in which 36 university-based addiction researchers and 62 community-based addiction treatment providers evaluated and ranked five widely recognized diagnostic instruments: (1) the SUD section of the Structured Clinical Interview for DSM-IV (SCID); (2) the SUD section of the Composite International Diagnostic Interview, 2nd ed. (CIDI-2); (3) the SUD section of the Diagnostic Interview Schedule for DSM-IV Diagnosis (DIS-IV); (4) the Diagnostic Statistical Manual-IV Checklist (DSM-IV Checklist); and (5) the Substance Dependence Severity Scale (SDSS). To assist the evaluation and ranking process, key characteristics of each instrument were presented in tabular and narrative formats. Participants ranked each instrument from 1 (most preferred) to 5 (least preferred). The SCID received the best overall mean score (2.24) followed by the CIDI-2 (2.59), DIS (2.94), DSM Checklist (3.40) and the SDSS (3.83). After discussing the pragmatic and scientific advantages and disadvantages of each instrument, the CTN Steering Committee selected the CIDI-2. The selection of the CIDI-2 standardizes the collection of diagnostic data and provides a common diagnostic tool for practitioners and clinical researchers in the CTN. Implications for practice/research collaboration and initiatives are explored.

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.

Should we use carbohydrate deficient transferrin as a marker for alcohol abusers?

Carbohydrate deficient transferrin (CDT) is one of the conventional markers for chronic alcohol consumption, is used by researchers and clinicians. A number of enzymes are affected by ethanol intake. The induction or inhibition of sialyl transferase and plasma sialidase may be involved in the CDT level elevation. An alteration of protein transport during post-translational modification could be a primary mechanism in the impairment of protein metabolism associated with chronic alcohol abuse. Transferrin being a steroid responsive protein, sex-based hormonal variations might contribute to the lower sensitivity of CDT. Varying hormonal statuses such as pregnancy, use of contraceptives, menopause/ menstrual cycle can alter iron homeostasis in women. CDT levels are markedly affected by iron homeostasis. Several CDT assay methods appeared promising, but it is not readily apparent which technique is the most accurate. Moreover, false-positive results of CDT have been reported in non-alcohol related hepatic failure and in rare conditions. Therefore clinical interpretation of CDT needs careful assessment in patients with alcohol-related or non-alcohol-related health disorders.

The use of biological laboratory markers in the diagnosis of alcohol misuse: an evidence-based approach

BACKGROUND

A large number of patients seen in clinical practice have an underlying alcohol problem. There is a pressing need for accurate methods to diagnose alcohol over-consumption objectively. Our aim was to determine how best to use biological markers to objectify alcohol problems in patients with clinical suspicion of alcohol misuse.

METHODS

A 6-month longitudinal multicenter trial was conducted, using four study groups (alcohol abusers, alcohol-dependents, healthy controls and consulting controls). CDT, GGT and MCV were measured. Statistical analyses used a computer learning system that created classification systems displayed in decision trees.

RESULTS

In 379 subjects the marker that best discriminated those with alcohol problems from controls was CDT. GGT then helped to differentiate between alcohol abuse and alcohol dependence in cases of high CDT. MCV, age and gender provided no extra information.

DISCUSSION

We recommend CDT as a first-line biological marker to confirm or disprove suspected alcohol misuse. High CDT plus GGT above normal points to alcohol dependence, while high CDT plus GGT below normal is evidence of alcohol abuse.

Biological markers in alcoholism

Alcohol biomarkers include tests indicative of acute or chronic alcohol consumption (state markers), and markers of a genetic predisposition to develop alcohol dependence after chronic exposure (trait markers). While a comprehensive trait marker for alcohol dependence has not been identified, a number of successful state markers for monitoring drinking status are used clinically. These tests provide direct or indirect ways to estimate the amounts of alcohol consumed and the duration of ingestion, and to detect any harmful effects on body functions resulting from long-term misuse. The most obvious method to prove recent drinking is by demonstrating the presence of ethanol in body fluids or breath, but, because ethanol is cleared fairly rapidly from the body, this method is limited to detect only very recent drinking. Measurement of urinary 5-hydroxytryptophol or ethyl glucuronide provide more sensitive methods to disclose recent drinking, because their washout constants are much longer than for ethanol. The liver functions test (GGT, AST and ALT in serum) and the mean corpuscular volume of erythrocytes (MCV) are among the standard diagnostic tools used to identify chronic alcohol exposure. The main disadvantage with these measures is that they have low sensitivity for recent excessive intake, and that raised levels may result from several causes besides heavy drinking, implying a low specificity for alcohol. Carbohydrate-deficient transferrin (CDT), which refers to changes in the carbohydrate composition of serum transferrin, is a more specific marker for identifying excessive alcohol consumption and monitoring abstinence during outpatient treatment. The alcohol biomarkers improves knowledge of drinking patterns in both individuals and populations, and they are also valuable tools for the objective evaluation of treatment efforts. Alcohol markers have, for example, found uses in early identification of at-risk and harmful drinking, and they help to monitor abstinence and relapse in response to outpatient treatment.

Current status of carbohydrate deficient transferrin, total serum sialic acid, sialic acid index of apolipoprotein J and serum beta-hexosaminidase as markers for alcohol consumption

AIMS

The purpose of this paper is to present a brief review of the literature and to summarize the current status of four biochemical markers for alcohol consumption, carbohydrate deficient transferrin (CDT), total serum sialic acid (TSA), sialic acid index of apolipoprotein J (SIJ) and serum beta-hexosaminidase (beta-HEX).

FINDINGS

Of these markers, CDT has been the most widely studied, is currently thought to be the most accurate predictor of alcohol consumption, is most readily available and is the only test approved by the FDA for the identification of heavy alcohol use. TSA and SIJ have the potential to be useful markers, but have only recently been discovered, are not readily available and have not yet been studied comprehensively. Finally, the relationship between serum beta-HEX and heavy alcohol consumption has been studied for about 20 years, but the test is not readily available and has not been widely accepted or used as a marker for heavy alcohol consumption.

CONCLUSIONS

These markers have the potential to be included in a combination of measurements to provide an accurate, more exact assessment of alcohol consumption in a variety of clinical and research settings.

A new modified γ-%CDT method improves the detection of problem drinking: studies in alcoholics with or without liver disease

BACKGROUND

The detection of excessive alcohol consumption by laboratory methods continues to lack sensitivity and specificity. Recent studies have suggested that diagnostic improvement may be achieved by combining carbohydrate-deficient transferrin (CDT) and gamma-glutamyltransferase (GT) measurements into a marker defined as gamma-CDT.

METHODS

We developed a new approach for determining gamma-CDT by using the data obtained from the Axis %CDT turbidimetric assays. Marker results were compared in the assessment of 65 alcoholics, who were either with (n=34) or without (n=31) liver disease, as analysed by clinical, laboratory, and morphological criteria. Reference individuals were 45 healthy volunteers who were either social drinkers or abstainers.

RESULTS

Gamma-GT and CDT results derived from both CDTect and %CDT measurements were used to calculate marker ratios as follows 0.8 x ln(GT)+1.3 x ln(CDT). With the established cut-off of 4.0 for the gamma-%CDT, the sensitivity of this method was 94% for men and 82% for women, as compared to 61% and 46% for %CDT and 70% and 73% for GT. The gamma-%CDT method was less dependent on liver status than the various other markers and showed the highest correlation with self-reported alcohol consumption (r=0.7254).

CONCLUSIONS

The data indicates that the new gamma-%CDT method yields improved diagnostic accuracy for the detection of excessive ethanol consumption.

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.

Analysis of carbohydrate-deficient transferrin (CDT) in vitreous humour as a forensic tool for detection of alcohol misuse

Analysis of carbohydrate-deficient transferrin concentration in vitreous humour (VH-CDT) has recently been demonstrated to be useful for diagnosis of pre-mortal alcohol misuse, but more knowledge considering possible methodological problems is warranted. In a forensic sample we examined the stability of VH-CDT during laboratory handling as well as the possible affection of time-dependent changes of total transferrin concentrations in vitreous humour (VH-Transferrin) in the dead body on VH-CDT as indicator of alcohol misuse. By use of a commercial assay designed for serum analysis (CDTect) it was possible to measure VH-CDT with high precision, and detectable amounts were found in 20 of 21 alcoholics and in two of seven controls. The compound was demonstrated to be stable in vitreous humour during laboratory handling, since the results of the first analysis were well reproducible after 4 months storage of the specimens (rs=0.86, P=0.0002). Transferrin concentrations in vitreous humour (VH-Transferrin) correlated to the estimated time since the individual last time had been alive before the forensic examination (rs=0.57, P<0.005). However, in this small sample the discriminating property of VH-CDT as indicator of alcohol misuse was not decisively affected, whether or not the variables "VH-Transferrin" and "estimated time since the individual last time had been alive" were considered in a multivariate logistic regression analysis (minor change in the beta-coefficient from 0.57 to 0.52, P=0.086). We conclude that CDT is stable in vitreous humour during proper laboratory handling and that detection of VH-CDT is primarily a marker of alcohol misuse before death. However, the results of this study do not exclude that time-dependent changes of VH-Transferrin, possibly affecting VH-CDT, may occur in the dead body. VH-CDT analysis should thus, at present, be restricted to cases with rather short post-mortal time interval.

Diagnostic characteristics of different carbohydrate-deficient transferrin methods in the detection of problem drinking: effects of liver disease and alcohol consumption

AIMS

Due to methodological heterogeneity, conflicting views have been expressed on the validity of CDT measurements in the detection of alcohol misuse.

METHODS

We compared the characteristics of the conventional CDTect method and the Axis turbidimetric CDT assays in the assessment of 62 alcoholics, who were either with (n = 33) or without (n = 29) liver disease, as analysed by combined clinical, laboratory, and morphological indices. Controls were 45 healthy volunteers who were either social drinkers or abstainers.

RESULTS

In the total sample of alcoholics, the sensitivity of the %CDT method, which excludes the trisialotransferrin isoform from the measurement, was 63% for men and 46% for women, as compared to 65% and 36% of CDTect, respectively. Both of these methods showed higher sensitivities than the %CDT-TIA method, which reacts with trisialotransferrin (32% and 25%, respectively). The assay specificities were 100% for men and 91% for women with %CDT, and 96% and 87% with the CDTect, respectively. The correlation between the CDTect and %CDT method was higher in men (r = 0.86) than in women (r = 0.57). The presence of liver disease was found to influence the results of the CDTect method, such that the highest CDT concentrations were observed in patients with mild to moderate liver disease, especially among women, whereas the %CDT method was less sensitive to the effect of liver pathology. The self-reported alcohol consumption from the 4 weeks prior to sampling showed a higher correlation between the %CDT results (r = 0.64, P < 0.0001) than with the CDTect results (r = 0.40; P < 0.01).

CONCLUSIONS

The data indicate that the new %CDT method offers advantages over the previous versions of the CDT methods. The improved characteristics may be most useful in assays for excessive alcohol consumption in female alcoholics, patients with liver disease, and in patients with abnormal serum transferrin concentrations.

The analysis of carbohydrate-deficient transferrin, marker of chronic alcoholism, using capillary electrophoresis

Carbohydrate-deficient transferrin (CDT) is currently considered to be the best available marker for the diagnosis of chronic alcoholism. A large variety of methods have been developed, demonstrating the need for standardisation. Commercially available anion-exchange chromatographic-based assays are easy to use and require no specialised, expensive instruments. However, these methods cannot identify genetic transferrin variants or the carbohydrate-deficient glycoprotein syndrome. In 1989, a capillary isoelectric focusing method was developed for quantitative measurement of CDT. Despite the optimal resolution, this method is not easily applied in a clinical routine environment due to the complexity of analysis. Capillary electrophoresis in a polymer network using coated capillaries allowed full resolution of the sialoforms of human transferrin. The drawbacks due to an expensive and time-consuming sample preparation were eliminated when a method in neat serum was developed. Capillary zone electrophoresis allowed full resolution of the transferrin isoforms with a high analytical performance in a short analysis time thanks to a strong electroosmotic flow. Genetic transferrin variants were easily detected, avoiding false-positive results. Also, using capillary zone electrophoresis, it was shown that CDT is a suitable marker of chronic alcohol abuse detection in transferrin CD (common/cathodal) variants.

Carbohydrate-deficient transferrin and gamma-glutamyltransferase for the detection and monitoring of alcohol use: results from a multisite study

BACKGROUND

The purpose of this article is to evaluate the biological marker of heavy alcohol use, carbohydrate-deficient transferrin (CDT), in contrast to the older and more widely used gamma-glutamyltransferase (GGT) for the detection and monitoring of heavy alcohol use.

METHODS

In this report, CDT and GGT sensitivity and specificity for heavy alcohol intake are examined in a large multisite study in which 444 recently admitted inpatient alcoholics were compared with 204 matched social drinker controls. In addition, changes in these biomarkers were evaluated during an initial abstinence period and biweekly over 14 weeks of monitoring to compare changes in CDT and GGT during continued abstinence or relapse.

RESULTS

CDT and GGT were comparable in identifying heavy alcohol consumption in men, but GGT appeared to be better for women. For both genders, when these markers were combined, there was better sensitivity than when used alone. CDT and GGT both decreased during 4 weeks of abstinence. When we used a 30% increase from baseline abstinent levels as an indicator, CDT appeared marginally better than GGT at indicating relapse in men but not in women. For men in particular, relapse over the course of the study was best identified by evaluating changes (30% increase) in both markers simultaneously.

CONCLUSIONS

These results support the utility of CDT, especially when used in conjunction with GGT, as an aid in detecting and monitoring heavy alcohol consumption.

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.

Chromatographic methods for the determination of markers of chronic and acute alcohol consumption

The development in chromatographic methods for the determination of markers of alcohol consumption is summarized in this review. The markers included in this article are ethanol in body fluids, ethanol congeners, fatty acid ethyl esters (FAEEs), ethyl glucuronide (EtG), cocaethylene (CE), carbohydrate-deficient transferrin (CDT), phosphatidylethanol (PEth), 5-hydroxytryptophol (5-HTOL), dolichol, ketone bodies, acetaldehyde-protein adducts, and salsolinol (SAL). Some of these markers for alcohol consumption do not only indicate previous ethanol ingestion, but also approximate the amount of intake and the time when ethanol ingestion last occurred. Basic information about the procedures, work-up, and chromatographic conditions are summarized in tables. Also the main metabolic pathways and reaction schemes are demonstrated in figures. Some examples of typical applications are presented. The author points out that in many of the reviewed papers validation data of the procedures as well as specificities and sensitivities were not clearly presented and consequently were not comparable.

Screening of binge drinking among patients on an emergency surgical ward

In a sample of 149 emergency surgical patients, binge drinking was assessed through interviews. Sensitivity, specificity, and positive and negative predictive values were calculated for three questionnaires-the Malmö modification of brief MAST (Mm-MAST), CAGE, and the Trauma Scale-and two biological markers-carbohydrate-deficient transferrin (CDT) and gamma-glutamyltransferase (GGT). Binge drinking was reported by 42% of male patients, aged 16-29 years; 66% of female patients, aged 16-29 years; 27% of male patients, aged 30-73 years; and 16% of female patients, aged 30-73 years. All alcohol biomarkers had low sensitivity to binge drinking among women. Mm-MAST alone and CAGE and CDT combined were sensitive to identifying binge drinking among men aged 30-73 years. The three questionnaires combined had a sensitivity of 0.82 to binge drinking among men aged 16-29 years.

Sensitivity and specificity of carbohydrate-deficient transferrin in drinking experiments and different patients

Information provided by patients about the amounts of alcohol they drink may often be too subjective and therefore unreliable. Because of the possible serious consequences of interactions between alcohol and medication, reliable laboratory test markers for alcohol consumption are needed. Carbohydrate-deficient transferrin (CDT) is at present the best available objective measure of drinking behavior. During a withdrawal trial, 92 alcohol-dependent patients who had been admitted to a hospital in an ethanol-intoxicated state were monitored over the following 28 days by using the percent carbohydrate-deficient transferrin (%CDT of total transferrin) (%CDT) method. At the time of admission, 63% showed elevated %CDT levels. After a subsequent period of abstinence, a decrease in %CDT levels was apparent in four different groups of patients, whereas in two groups, comprising the greatest number of patients, normal %CDT levels were evident after 14 days of abstinence. In patients whose CDT levels were very high at study initiation, it took at least 21 to 28 days--and sometimes longer--for CDT to decrease to the radioimmunoassay (RIA) %CDT test cutoff point of 2.5. In a further study of 56 male alcohol-dependent patients, we measured liver enzyme concentrations, mean corpuscular volume (MCV), and four CDT variants on the first day of evidence of withdrawal syndrome. We found a significant correlation between results on the Munich Alcoholism Test (MALT) and MCV levels; among gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels; and among all four CDT variants. A cluster analysis yielded three clusters: (1) GGT, AST, and ALT levels; (2) MCV levels and MALT results; and (3) all CDT measurement variants. We conclude that these three clusters measure different detriments to the patient and that all available CDT variants are commensurate.

Carbohydrate-deficient transferrin for detection and monitoring of sustained heavy drinking. What have we learned? Where do we go from here?

Carbohydrate-deficient transferrin (CDT) has been widely investigated as a biological marker of heavy alcohol consumption. In general, it has been found to be at least as sensitive and probably more specific than gamma-glutamyltransferase (GGT). Because the two analytes are not highly correlated, their use in parallel enhances the sensitivity of detection of heavy alcohol consumption, especially in clinical populations. Women as a group produce more CDT under natural conditions and may produce less CDT in response to heavy drinking. Carbohydrate-deficient transferrin has found a place in the monitoring of alcoholics during treatment. Changes in CDT levels from individualized baseline values seem to be more sensitive to lower level relapse drinking than is the use of raw cut-off values. There are some conditions such as severe liver disease in which higher than normal levels of CDT are produced, thereby reducing the specificity of this marker for detecting heavy drinking under certain conditions. Future directions for the use of CDT include standardization and automation of measurement technology, evaluation of how to use it wisely in myriad medical and institutional settings, understanding more thoroughly the gender issues in its production, and greater evaluation of its performance as a monitoring tool during treatment and follow-up situations. How to combine CDT with both verbal tools of alcohol assessment and newer biological markers will also need more extensive evaluation.

Interference of Transferrin Isoform Types with Carbohydrate-deficient Transferrin Quantification in the Identification of Alcohol Abuse

Background: Isoforms of transferrin interfere with measurement of carbohydrate-deficient transferrin (CDT) as a marker of heavy alcohol consumption. We evaluated the rate of inaccurate CDT results by immunoassays.

Methods: We studied 2360 consecutive sera (1614 individuals) submitted for CDT assay without clinical information as well as samples from 1 patient with a congenital disorder of glycosylation (CDG Ia) and from 6 healthy carriers of CDG Ia. The CDTect, %CDT-TIA, and new %CDT immunoassays were compared with HPLC (%CDT-HPLC). Transferrin isoform pattern were evaluated by isoelectric focusing (IEF).

Results: Transferrin BC and CD heterozygotes were found at frequencies of ∼0.7% and ∼0.2%, respectively. Another transferrin C subtype, where di- and trisialotransferrin partly coeluted (tentatively identified as C2C3), was observed in ∼0.6%. Compared with the %CDT-HPLC method, the immunoassays often produced low results for transferrin BC and high results for transferrin CD and “C2C3”. A very high trisialotransferrin value (frequency ∼1%) often produced high CDT immunoassay results. In four of six healthy carriers of CDG Ia, a- and disialotransferrin were highly increased and the HPLC and IEF isoform patterns were indistinguishable from those in alcohol abuse.

Conclusions: Rare transferrin isoform types and abnormal amounts of trisialotransferrin (total frequency ∼2–3%) may cause incorrect determination of CDT with immunoassays. The observed variants were readily identified by HPLC and IEF, which can be recommended for verification of CDT immunoassay results in doubtful cases. In healthy carriers of CDG Ia, CDT is high by all assays.

Association of carbohydrate-deficient transferrin (CDT) and gamma-glutamyl-transferase (GGT) with serum lipid profile in the Finnish population

BACKGROUND

Moderate consumption of alcohol may reduce mortality from vascular diseases. The beneficial effects of alcohol may partly be mediated by its effects on lipoprotein metabolism. We studied the connection between alcohol consumption and the serum lipid profile from a well-documented national health program study.

METHODS AND RESULTS

Carbohydrate-deficient transferrin (CDT) and gamma-glutamyl-transferase (GGT) were used as biochemical markers for alcohol consumption. The laboratory analyses were carried out on 5675 subjects (3097 males and 2578 females). The subjects were divided into quartiles on the basis of CDT or GGT value. The highest CDT quartile and the lowest GGT quartile seemed to be associated with a favorable lipid profile and the lowest CDT quartile and the highest GGT quartile were associated with an unfavorable lipid profile. Serum high density lipoprotein (HDL) cholesterol values were significantly higher and triglycerides lower with increasing serum CDT concentrations for both men and women. Increasing serum GGT was associated with higher serum total cholesterol and higher triglycerides in both men and women and lower HDL cholesterol in men.

CONCLUSIONS

CDT and GGT seem to detect different populations of subjects in regard to lipid metabolism. These observations may lead to a better understanding of the effects of alcohol consumption on lipids as well as mechanisms behind favorable and detrimental effects of alcohol on vascular diseases.

CONDENSED ABSTRACT

Carbohydrate-deficient transferrin (CDT) and gamma-glutamyl-transferase (GGT) were used as biochemical markers for alcohol consumption. A total of 3097 males and 2578 females were divided into quartiles on the basis of their CDT or GGT values. The highest CDT quartiles had higher HDL and lower triglycerides, whereas the highest GGT quartiles appeared to be associated with higher total cholesterol and triglycerides in both genders and lower HDL in men. CDT and GGT seem to detect different populations of subjects in regard to lipid metabolism. These observations may have important clinical and public health implications.

The role of laboratory tests in alcoholism treatment

Although assessment in the field of alcoholism treatment is generally verbal in nature, biological tests can also provide counselors and program evaluators useful and unique information. Five such laboratory measures are briefly described, with particular emphasis on carbohydrate deficient transferrin, a biomarker recently approved by the FDA. Applications for laboratory tests in alcohol screening, motivating patients, and monitoring treatment progress are also proposed.

Carbohydrate-deficient Transferrin as a Marker of Chronic Alcohol Abuse: A Critical Review of Preanalysis, Analysis, and Interpretation

Background: Carbohydrate-deficient transferrin (CDT) is used for diagnosis of chronic alcohol abuse. Some 200–300 reports on CDT have been published in impact factor-listed journals. The aims of this review were to condense the current knowledge and to resolve remaining issues on CDT.

Approach: The literature (1976–2000) was searched using MEDLINE and Knowledge Server with “alcohol and CDT” as the search items. The data were reviewed systematically, checked for redundancy, and organized in sequence based on the steps involved in CDT analysis.

Content: The review is divided into sections based on microheterogeneity of human serum transferrin (Tf), definition of CDT, structure of human serum CDT, pathomechanisms of ethanol-induced CDT increase, preanalysis, analysis, and medical interpretation (postanalysis). Test-specific cutoff values for serum CDT and causes of false positives and negatives for chronic alcohol abuse are discussed and summarized.

Summary: Asialo- and disialo-Fe2-Tf, which lack one or two complete N-glycans, and monosialo-Fe2-Tf (structure remains unclear) are collectively referred to as CDT. Diminished mRNA concentration and glycoprotein glycosyltransferase activities involved in Tf N-glycan synthesis and increased sialidase activity most likely account for alcohol-induced increases in CDT. Knowledge about in vivo and in vitro effects on serum CDT is poor. Reliable CDT and non-CDT fractionation is needed for CDT measurement. Analysis methods with different analytical specificities and recoveries decreased the comparability of values and statistical parameters of the diagnostic efficiency of CDT. CDT is the most specific marker of chronic alcohol abuse to date. Efforts should concentrate on the pathomechanisms (in vivo), preanalysis, and standardization of CDT analysis.