Carbohydrate-deficient transferrin (CDT) as a marker of alcohol abuse: a critical review of the literature 2001-2005

Progress in monitoring alcohol consumption and alcohol abuse by phosphatidylethanol

For early diagnosis and therapy of alcohol-related disorders, alcohol biomarkers are highly valuable. Concerning specificity, indirect markers can be influenced by nonethanol-related factors, whereas direct markers are only formed after ethanol consumption. Sensitivity of the direct markers depends on cut-offs of analytical methods, material for analysis and plays an important role for their utilization in different fields of application. Until recently, the biomarker phosphatidylethanol has been used to differentiate between social drinking and alcohol abuse. After method optimization, the detection limit could be lowered and phosphatidylethanol became sensitive enough to even detect the consumption of low amounts of alcohol. This perspective gives a summary of most common alcohol biomarkers and summarizes new developments for monitoring alcohol consumption habits.

Biomarkers of iron status and trace elements in welders

Iron status was studied in 137 welders exposed to a geometric mean (GM) air concentration of 214 μg/m(3) (range 1-3230) of manganese (Mn), in 137 referents and in 34 former welders. The GM concentrations of S-ferritin were 119 (3-1498), 112 (9-1277) and 98 (12-989) μg/L (p=0.24) in the three groups, respectively. Also the GM concentrations of S-hepcidin were not significantly different between the groups (8.4 μg/L (2.8-117); 6.6 μg/L (1.8-100); 6.5 μg/L (1.2-22)) (p=0.22). Multiple linear regression analysis including all welders and referents showed an increase in the concentration of S-ferritin associated with having serum carbohydrate deficient transferrin (S-CDT) above the upper reference limit of ≥1.7%, indicating high alcohol consumption. Serum C-reactive protein was not associated with exposure as welders, but an association with S-ferritin was shown. The GM S-ferritin concentrations among all welders and referents with S-CDT≥1.7% were 157 μg/L (95% CI 113-218) as compared to 104 μg/L (95% CI 94-116) (p=0.02) in those with S-CDT<1.7%. The GM concentrations of Mn in biological fluids were higher in the welders as compared to the referents, while S-Fe, S-Co and B-Co were statistically significantly lower. This could suggest a competitive inhibition from Mn on the uptake of Fe and Co. Increasing concentrations of S-CDT was associated with higher S-Mn, S-Fe and B-Co in the multiple linear regression analysis. The association between S-CDT and S-Fe remained when all subjects with high S-CDT (≥1.7%) were excluded, suggesting increased uptake of Fe even at lower alcohol consumption.

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.

False negativity to carbohydrate-deficient transferrin and drugs: a clinical case

Introduction:

In this work we report on the possible effect of the medical therapy on CDT concentration in a chronic alcohol abuser, with known medical history (July 2007 – April 2012) and alcohol abuse confirmed by relatives.

Case history:

At the end of 2007, patient displayed the following laboratory results: AST 137 U/L, ALT 120 U/L, GGT 434 U/L, MCV 101 fL and CDT 3.3%. On December 2007, after double coronary artery bypass surgery, he began a pharmacological treatment with amlodipine, perindopril, atorvastatin, isosorbide mononitrate, carvedilol, ticlopidine and pantoprazole. In the next months, until may 2011, the patient resumed alcohol abuse, as confirmed by relatives; however, CDT values were repeatedly found negative (0.8% and 1.1%) despite elevated transaminases and GGT, concurrent elevated ethyl glucuronide concentration (> 50 mg/L) and blood alcohol concentration (> 1 g/L). Alcohol consumption still continued despite increasing disulfiram doses ordered by an Alcohol Rehab Center. On May 2011, the patient was transferred to a private medical center where he currently lives.

Conclusions:

This study suggests the possibility that a medical therapy including different drugs may hamper the identification of chronic alcohol abusers by CDT.

Monitoring population levels of alcohol consumption in pregnant women: a case for using biomarkers

A challenge to biochemically monitoring alcohol consumption in pregnancy is the prohibitive costs of collecting thousands of blood samples. This pilot study looks at the feasibility of using residual samples to monitor chronic and acute alcohol consumption in pregnancy. Residual anomalies screening samples (n = 150, 2006/7) were tested for carbohydrate-deficient transferrin (CDT, chronic marker) and ethyl glucuronide (EtG, acute marker). Valid readings were obtained for CDT but not EtG. These results pave the way for a larger representative study, to provide, for the first time, a national biochemical baseline estimate of chronic alcohol consumption in the pregnant population.

Effect of transferrin glycation on the use of carbohydrate-deficient transferrin as an alcohol biomarker

AIMS

Measurement of an alcohol-induced shift in the serum transferrin glycosylation pattern, termed carbohydrate-deficient transferrin (CDT), is used as a biomarker for sustained high alcohol consumption. The present work examined whether non-enzymatic reaction of transferrin with glucose (glycation) might interfere with the use of CDT as an alcohol biomarker.

METHODS

The blood specimens were leftover volumes from the routine sample pool. Plasma and serum were collected among samples submitted for hemoglobin A1c (HbA1c) and CDT testing. Quantification of individual transferrin glycoforms in percentage of total transferrin was performed by an HPLC candidate CDT reference method.

RESULTS

Incubating serum spiked with 20 or 200 mmol/l glucose caused time- and dose-dependent changes in the chromatographic profile of transferrin glycoforms, resulting in gradually wider peaks and reduced relative amounts of disialo- and trisialotransferrin. No similar chromatographic effects were seen in samples collected from diabetic patients with elevated HbA1c (>68 mmol/mol) values. These samples instead showed slightly higher mean %disialotransferrin levels (1.21%) compared with low HbA1c (<44 mmol/mol) samples (mean 1.06%; P = 0.023), pointing at a higher alcohol consumption level in the former group. Altogether ∼5% of the CDT values exceeded the cutoff. There was no significant difference in phosphatidylethanol (PEth) levels between the high and low HbA1c samples, but several (∼14%) showed elevated PEth concentrations.

CONCLUSION

Glycation of serum transferrin in vivo was indicated to differ from that in vitro, and suggested not to interfere with %CDT testing by the HPLC method. The results indicated that CDT and PEth are useful as objective, complementary alcohol biomarkers to identify risky drinking also in diabetic subjects.

Microheterogeneity of serum β-hexosaminidase in chronic alcohol abusers in a driver's license regranting program

BACKGROUND

Carbohydrate-deficient transferrin (CDT) is one of the best indicators for chronic alcohol abuse and detection of relapse. In this study, we explore the microheterogeneity of β-hexosaminidase (β-HEX) in chronic alcohol abusers in the framework of a driver's license regranting program. Studies have shown that increased serum activity of β-HEX B (isoforms P, I, and B) may be a sensitive marker for chronic alcohol abuse. Here, we describe methodology, limitations, and correlation of β-HEX isoforms with CDT.

METHODS

CDT was assayed at the central laboratory of the Ghent University Hospital by capillary zone electrophoresis, measured on the Capillarys 2™ system and was expressed as a percentage of total serum transferrin (%CDT). Serum of chronic alcohol abusers was compared to nonheavy drinkers using agarose gel isoelectric focusing (IEF). Total β-HEX activity was assayed fluorimetrically following preparative IEF in 81 subjects. β-HEX isoforms were investigated and compared between nonheavy drinkers and heavy drinkers.

RESULTS

Agarose gel IEF shows additional cathodal bands in serum of chronic alcohol abusers. Mean total β-HEX activity between pH 6.8 and 7.7, designated as HEX-7, showed the highest correlation with %CDT (r = 0.70, p < 0.0001, n = 68). In a selected subgroup, where CDT could not be quantified (n = 13) because of an atypical electropherogram, HEX-7 was in concordance with either estimated %CDT value or liver enzyme activities.

CONCLUSIONS

In this proof-of-concept study, we introduce a novel approach to quantify β-HEX isoforms using preparative IEF and fluorimetry. A highly significant correlation of HEX-7 and %CDT has been found. Because of exclusion of the P isoform, HEX-7 could be a useful supplementary marker for detecting chronic alcohol abuse.

Non-oxidative ethanol metabolites as a measure of alcohol intake

Recent alcohol intake can be monitored by the measurement of indirect biomarkers. Elevated levels of liver enzymes (i.e. gamma-glutamyl transferase (GGT), alanine amino transferase (ALT) and aspartate amino transferase (AST)) in blood are commonly used in clinical practice as an indicator of alcohol-induced liver damage. With the exception of carbohydrate-deficient transferrin (CDT), the specificity of indirect markers is only moderate because many cases of elevated levels are unrelated to alcohol consumption. Because of their intermediate half-life and tendency to accumulate in hair, non-oxidative ethanol metabolites can be used as markers with an intermediate timeframe between ethanol measurements and GGT and CDT with regard to recent alcohol consumption occurring between hours to 1 week. Additionally, these biomarkers offer a high ethanol-specificity in combination with approximately a two-fold higher sensitivity in comparison with indirect alcohol markers. In case of forensic use of direct ethanol metabolites, caution has to be taken in interpretation and pre-analytical pitfalls should be considered.

Phosphatidylethanol in blood as a marker of chronic alcohol use: a systematic review and meta-analysis

The present paper aims at a systematic review of the current knowledge on phosphatidylethanol (PEth) in blood as a direct marker of chronic alcohol use and abuse. In March 2012, the search through “MeSH” and “free-text” protocols in the databases Medline/PubMed, SCOPUS, Web of Science, and Ovid/Embase, combining the terms phosphatidylethanol and alcohol, provided 444 records, 58 of which fulfilled the inclusion criteria and were used to summarize the current evidence on the formation, distribution and degradation of PEth in human blood: (1), the presence and distribution of different PEth molecular species (2), the most diffused analytical methods devoted to PEth identification and quantization (3), the clinical efficiency of total PEth quantification as a marker of chronic excessive drinking (4), and the potential utility of this marker for identifying binge drinking behaviors (5). Twelve papers were included in the meta-analysis and the mean (M) and 95% confidence interval (CI) of total PEth concentrations in social drinkers (DAI ≤ 60 g/die; M = 0.288 μM; CI 0.208–0.367 μM) and heavy drinkers (DAI > 60 g/die; M = 3.897 μM; CI 2.404–5.391 μM) were calculated. The present analysis demonstrates a good clinical efficiency of PEth for detecting chronic heavy drinking.

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.

Disialo-trisialo bridging of transferrin is due to increased branching and fucosylation of the carbohydrate moiety

BACKGROUND

Carbohydrate deficient transferrin (CDT) is used for detection of alcohol abuse and follow-up. High performance liquid chromatography (HPLC) of transferrin glycoforms is highly specific for identification of alcohol abuse, but unresolved disialo- and trisialotransferrin glycoforms sometimes makes interpretation difficult. The cause of this phenomenon is unknown, cannot be explained by genetic variants of transferrin, but seems to be associated with liver disease.

METHODS

Nineteen serum samples showing di-tri bridging when analyzed by HPLC were collected. Transferrin was purified by affinity chromatography, and N-linked oligosaccharides were released enzymatically. The N-glycans were further analyzed by high performance anion-exchange chromatography with pulsed amperometric detection and MALDI-TOF mass spectrometry.

RESULTS

The HPLC-analysis showed three different types of glycoform patterns. The N-glycans from fifteen samples showed patterns with increased number of triantennary structures containing one or two fucose residues. One sample contained an increased amount of triantennary glycans without fucose. Three samples showed a glycosylation pattern similar to normal transferrin.

CONCLUSIONS

The di-tri bridging phenomenon was associated with alterations in transferrin glycosylation in the majority of cases. Transferrin contained a higher extent of triantennary and often fucosylated N-linked oligosaccharides. These results may be important in future diagnostic approaches to liver diseases.

[Carbohydrate-deficient transferrin in doping and non-doping athletes]

The determination of carbohydrate deficient transferrin (CDT) concentration is primarily used in social security studies as a proof of regular alcohol consumption exceeding the amount of 60 grams per day.

AIMS

The present study was performed to investigate into how carbohydrate deficient transferrin CDT values in serum are affected by the so-called food supplements and chemicals included in doping lists.

METHODS

The investigation was carried out in 15 bodybuilders of two sport clubs and in 10 boxers. All sportsmen were males. In both groups serum carbohydrate deficient transferrin (CDT%), median red blood cell volume and (MCV) gamma-glutamyl-transpeptidase (GGT) values were measured.

RESULTS

The authors found a significant difference between the two groups only in carbohydrate deficient transferrin CDT% that was the CDT% value in bodybuilders was twice as high as in boxers.

CONCLUSION

Not all the details of the specificity of carbohydrate deficient transferrin (CDT) concentration are known, however, the remarkably high sensitivity of the method makes it suitable and probably economically effective as a pre-screening tool in doping tests.

Comparison of ethyl glucuronide in hair with self-reported alcohol consumption

AIMS

Ethyl glucuronide (EtG) in hair is a proposed biomarker for alcohol consumption. This study compares hair EtG concentrations with self-reported alcohol consumption data, in individuals with a range of alcohol use.

METHODS

Hair was collected from 100 participants with a range of alcohol use. Participants completed an Alcohol Use Disorders Identification Test C questionnaire to record alcohol consumption. Participants were categorized into one of the four groups: tee-totallers (consuming 0 units a week), lower-risk drinkers (1-21 units a week), increasing-risk drinkers' consuming (22-50 units a week) and high-risk drinkers (over 50 units a week). Hair from the proximal 3 cm was analysed for EtG using gas chromatography-mass spectrometry/mass spectrometry.

RESULTS

EtG was detected in 29 out of 100 hair samples. Based on the Society of Hair Testing (SOHT) threshold of 30 pg/mg EtG, the hair test identified alcohol consumption in 57.9% of high-risk drinkers, 45.5% of increasing-risk drinkers and only 9.8% of lower-risk drinkers. EtG sensitivity was highest for high-risk drinkers (consuming more than 50 units a week), identified to be 0.52 using a 30 pg/mg threshold and 0.58 using a 45 pg/mg threshold. A positive result is highly likely to indicate any drinking (positive predictive value, 1.00). A negative result does not provide good evidence for abstinence (negative predictive value, 0.23).

CONCLUSIONS

EtG has been identified to be a low sensitivity marker that cannot be used quantitatively to determine alcohol exposure. EtG can be used qualitatively to indicate alcohol consumption with a positive result providing strong evidence for an individual drinking within the past 3 months.

Clinical performance of the carbohydrate-deficient transferrin (CDT) assay by the Sebia Capillarys2 system in case of cirrhosis. Interest of the Bio-Rad %CDT by HPLC test and Siemens N-Latex CDT kit as putative confirmatory methods

BACKGROUND

The CDT assay used to detect chronic alcohol abuse is difficult with cirrhotic patients. This article describes the performances of several CDT assays in case of cirrhosis. The CDT-Capillarys assay by capillary zone electrophoresis was used for initial testing. Two additional methods were tested as putative confirmatory methods.

METHODS

110 patients with known hepatic status had their CDT measured by the Capillarys2 or alternative methods. Self-reported alcohol intake was used to assess the performances of CDT assays.

RESULTS

Capillarys2 performance was lower in case of cirrhosis, many electropherograms displaying various abnormalities. We used the proper separation of the di- and tri-sialotransferrin peaks to select reliable profiles. This selection led to the classification of cirrhotic and non-cirrhotic patients in abusers and abstainers with similar performances. However, no interpretation was available for 54% of the cirrhotic patients and neither the BioRad %CDT by HPLC test, nor the Siemens N-Latex CDT kit was suitable as confirmatory methods for these samples.

CONCLUSIONS

An attentive profile examination is required for the validation of Capillarys CDT results of cirrhotic patients. Reliability is significantly improved when samples with an improper separation are excluded. To date, no commercial test can confirm the excluded samples.

Alcoholic liver disease: pathogenesis and new targets for therapy

Alcoholic liver disease (ALD) is a major cause of morbidity and mortality worldwide. The spectrum of disease ranges from fatty liver to hepatic inflammation, necrosis, progressive fibrosis and hepatocellular carcinoma. In developed countries, ALD is a major cause of end-stage liver disease that requires transplantation. The most effective therapy for ALD is alcohol abstinence. However, for patients with severe forms of ALD (that is, alcoholic hepatitis) and for those who do not achieve abstinence from alcohol, targeted therapies are urgently needed. The development of new drugs for ALD is hampered by the scarcity of studies and the drawbacks of existing animal models, which do not reflect all the features of the human disease. However, translational research using liver samples from patients with ALD has identified new potential therapeutic targets, such as CXC chemokines, osteopontin and tumor necrosis factor receptor superfamily member 12A. The pathogenetic roles of these targets, however, remain to be confirmed in animal models. This Review summarizes the epidemiology, natural history, risk factors and current knowledge of the pathogenetic mechanisms of ALD. In addition, this article provides a detailed description of the findings of these translational studies and of the animal models used to study ALD.

Operating characteristics of carbohydrate-deficient transferrin (CDT) for identifying unhealthy alcohol use in adults with HIV infection

Unhealthy alcohol use (the spectrum of risky use through dependence) is common in HIV-infected persons, yet it can interfere with HIV medication adherence, may lower CD4 cell count, and can cause hepatic injury. Carbohydrate-deficient transferrin (CDT), often measured as %CDT, can detect heavy drinking but whether it does in people with HIV is not well established. We evaluated the operating characteristics of %CDT in HIV-infected adults using cross-sectional data from 300 HIV-infected adults with current or past alcohol problems. Past 30-day alcohol consumption was determined using the Timeline Followback (TLFB), a validated structured recall questionnaire, as the reference standard. Sensitivity and specificity of %CDT (at manufacturer's cut-off point of 2.6%) for detecting both "at-risk" (≥4 drinks in a day or >7 drinks per week for women, ≥5 drinks in a day or >14 per week for men) and "heavy" drinking (≥4 drinks in a day for women, ≥5 drinks in a day for men on at least seven days) were calculated. Receiver operating characteristic (ROC) curves were estimated to summarize the diagnostic ability of %CDT for distinguishing "at risk" and "heavy" levels of drinking. Exploratory analyses that stratified by gender and viral hepatitis infection were performed. Of 300 subjects, 103 reported current consumption at "at-risk" amounts, and 47 reported "heavy" amounts. For "at-risk" drinking, sensitivity of %CDT was 28% (95% confidence interval (CI) 19%, 37%), specificity 90% (95% CI 86%, 94%); area under the ROC curve (AUC) was 0.59. For "heavy" drinking, sensitivity was 36% (95% CI 22%, 50%), specificity 88% (95% CI 84%, 92%); AUC was 0.60. Sensitivity appeared lower among women and those with viral hepatitis; specificity was similar across subgroups. Among HIV-infected adults, %CDT testing yielded good specificity, but poor sensitivity for detecting "at-risk" and "heavy" alcohol consumption, limiting its clinical utility for detecting unhealthy alcohol use in this population.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for the period 2005-2006

This review is the fourth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2006. The review covers fundamental studies, fragmentation of carbohydrate ions, method developments, and applications of the technique to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, glycated proteins, glycolipids from bacteria, glycosides, and various other natural products. There is a short section on the use of MALDI-TOF mass spectrometry for the study of enzymes involved in glycan processing, a section on industrial processes, particularly the development of biopharmaceuticals and a section on the use of MALDI-MS to monitor products of chemical synthesis of carbohydrates. Large carbohydrate-protein complexes and glycodendrimers are highlighted in this final section.

Improved capillary electrophoresis determination of carbohydrate-deficient transferrin including on-line immunosubtraction

The instrumental analysis of carbohydrate-deficient transferrin (CDT), a recognized marker of chronic alcohol abuse, is most commonly carried out by high-performance liquid chromatography (HPLC) or capillary zone electrophoresis (CZE). Between these two techniques, CZE shows higher efficiency and productivity, but is often reported to be inferior to HPLC in terms of selectivity, because of a less specific ultraviolet detection wavelength than HPLC. On these grounds, the present work was aimed at the development of an improved CZE method for CDT determination, including an on-line immunosubtraction step specifically aimed at enhancing the analytical specificity of CZE determination. The analytical conditions were as follows: uncoated fused silica capillary, 30 microm x 60 cm (L = 50 cm to detector); running buffer, 100 mmol/L borate and 6 mmol/L DAB (1,4-diaminobutane), pH 8.3; voltage, 30 kV; temperature, 25 degrees C; detection, 200 nm. Under the described CZE conditions, a baseline separation between all the CDT related peaks was achieved with good analytical performances in terms of both precision and accuracy. In order to achieve unequivocal recognition of the CDT peaks, an in-capillary immunosubtraction step was included by loading a plug of anti-human transferrin antibody solution after the sample plug. This analytical approach was applied successfully to recognize CDT peaks in the presence of potential interferences.

Toward standardization of carbohydrate-deficient transferrin (CDT) measurements: II. Performance of a laboratory network running the HPLC candidate reference measurement procedure and evaluation of a candidate reference material

Carbohydrate-deficient transferrin (CDT) is a descriptive term used for a temporary change in the transferrin glycosylation profile caused by alcohol, and used as a biomarker of chronic high alcohol consumption. The use of an array of methods for measurement of CDT in various absolute or relative amounts, and sometimes covering different transferrin glycoforms, has complicated the comparability of results and caused confusion among medical staff. This situation prompted initiation of an IFCC Working Group on CDT standardization. This second publication of the WG-CDT covers the establishment of a network of reference laboratories running a high-performance liquid chromatography (HPLC) candidate reference measurement procedure, and evaluation of candidate secondary reference materials. The network laboratories demonstrated good and reproducible performance and thus can be used to assign target values for calibrators and controls. A candidate secondary reference material based on native human serum lyophilized with a cryo-/lyoprotectant to prevent protein denaturation was found to be commutable and stable during storage. A proposed strategy for calibration of different CDT methods is also presented. In an external quality assurance study involving 66 laboratories and covering the current routine CDT assays (HPLC, capillary electrophoresis and immunoassay), recalculation of observed results based on the nominal values for the candidate calibrator reduced the overall coefficient of variation from 18.9% to 5.5%. The logistics for distribution of reference materials and review of results were found to be functional, indicating that a full reference system for CDT may soon be available.

Changes in transferrin glycosylation during pregnancy may lead to false-positive carbohydrate-deficient transferrin (CDT) results in testing for riskful alcohol consumption

BACKGROUND

An alcohol-induced change in serum transferrin glycosylation, termed carbohydrate-deficient transferrin (CDT), is widely used as a biomarker of heavy long-term drinking. This study examined the transferrin glycosylation profile and the risk for false-positive CDT results during pregnancy.

METHODS

Serum samples were collected from 24 healthy pregnant women starting in gestation week 9-21, throughout pregnancy, and 8 or more weeks after delivery. Altogether 171 sera (5-9 samples/person) were analysed. Transferrin glycoforms were quantified as a percentage of total transferrin, using an HPLC candidate reference method for CDT.

RESULTS

During pregnancy, the relative disialo-, pentasialo- and hexasialotransferrin levels increased gradually, whereas trisialo- and tetrasialotransferrin were reduced. This effect was most pronounced in the third trimester. For disialotransferrin, the main target in CDT testing, initial values of 1.07 ± 0.17% (mean ± SD) increased to 1.61 ± 0.23% before delivery (~50% increase). Nine (38%) pregnant women reached %disialotransferrin values ≥ 1.7% (97.5th percentile for controls) but all results were < 2.0%. In the postpartum samples, all glycoform levels had returned towards the starting values.

CONCLUSIONS

These results suggest that the cutoff for %disialotransferrin and %CDT employed to indicate heavy long-term drinking need to be raised slightly in pregnant women, to minimize the risk for false-positive results on CDT testing.

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).

A new CE-ESI-MS method for the detection of stable hemoglobin acetaldehyde adducts, potential biomarkers of alcohol abuse

A new CE-ESI-MS method was developed to provide a simple way to study changes to hemoglobin (HbA) induced by acetaldehyde (Ach) in vitro. Instrumental parameters were univariately optimized in order to maximize the sensitivity of the CE-ESI-MS method. The electrophoretic separations were carried out in poly-E323-coated capillaries using 60 mM formic acid raised to pH 3.0 with ammonia and containing 5% 2-propanol while the sheath liquid, 2-propanol/water (30:70) with 0.1% formic acid, was delivered at 1.0 microL/min through a coaxial sheath flow electrospray interface. The HbA was incubated with Ach for intervals up to 24 h at concentration varying in the window 0.2-20 mM. Four stable Ach-hemoglobin adducts in the hemoglobin tryptic digest were observed at the submillimolar Ach concentration and characterized by MS/MS experiments: although the alpha and beta N-amino terminal modifications were expected, the two internal ones arising, respectively, from the condensation of Ach molecules on the histidine residue in position 4 in alpha4 (i.e. the fourth peptide after tryptic digestion of alpha chain starting from amino terminal) and on the asparagine residue in position 2 in beta3, were identified for the first time. During the in vitro experiments higher concentrations of Ach were also used; however, it was not possible to identify any other stable modification of hemoglobin. Interestingly, those stable modifications are the only ones in vivo identified in the hemoglobin of moderate alcohol drinkers.

Quantifying Carbohydrate-Deficient Transferrin in Serum

Alcohol abuse is a major public health problem with significant consequences for the society and economy. A biomarker commonly used for the analysis of alcohol abuse is serum CDT (carbohydrate-deficient transferrin). Very few conditions other than heavy alcohol consumption over a period of two to three weeks cause serum CDT to rise. Here we report a capillary electrophoresis method that is able to quantify CDT and the high resolution and reproducibility of the method make it possible to identify potential variants while avoiding false results.

Alcohol biomarkers in patients admitted for trauma

BACKGROUND

To assess the value of blood alcohol levels (BAL) and carbohydrate-deficient transferrin (CDT) in trauma patients.

METHODS

A prospective study was conducted among 213 patients admitted to a university hospital after trauma. Outcomes of interest included the development of alcohol withdrawal, infections, respiratory problems, cardiac events, thromboembolism, and length of stay.

RESULTS

The majority (78%) of the trauma patients in the study was males over the age of 18. Seventy-five percent were reported drinking an alcohol-containing beverage in the previous 30 days, 34% had > or =5 heavy drinking days, and 18.7% met current DSM-IV criteria for alcohol abuse and 13.1% current criteria for dependence. Twenty-two percent (n = 48) had a positive BAL and 14% (n = 30) a CDT level >2.5%. Twelve percent (n = 27) of the sample developed alcohol withdrawal and 55% (n = 113) had one or more adverse health events during their hospitalization. The development of alcohol withdrawal was associated with an admission CDT >2.5% (chi(2): 4.77, p < 0.029) and/or a positive BAL (chi(2): 54.01, p < 0.001). The alcohol biomarkers identified 13 male and 3 female high-risk patients (7.4% of the total sample) who denied excessive alcohol use, and who would have been missed if these markers were not used. A composite morbidity trauma score composed of 25 adverse health events was associated with a positive BAL (p < 0.022).

CONCLUSION

The study provides additional empirical evidence that supports the use of BAL in all patients admitted for trauma. The usefulness of CDT in trauma patients remains unclear and will require larger samples in more critically ill patients.

Carbohydrate‐deficient transferrin determined in blood microsamples from healthy newborns by using capillary zone electrophoresis

OBJECTIVE

There is a paucity of studies on quantitative determination of carbohydrate-deficient transferrin (CDT) in newborns. The aim of our study was therefore to determine CDT concentrations in newborns by using capillary zone electrophoresis (CZE).

MATERIAL AND METHODS

Capillary blood was collected from the heels of 28 at-term healthy newborns, simultaneously with the Guthrie card screening. Forty-seven adults were examined as controls. CZE separations were performed with a P/ACE MDQ capillary electropherograph in uncoated fused-silica capillaries using a commercial reagent kit. After iron saturation, the samples were loaded by application of 0.5 psi for 15 s, and separated under 28kV with UV detection. All relevant transferrin (Tf) glycoforms were separated within 7 min. CDT quantification (%CDT) was carried out by calculating the percentage ratio between the sum of the peak areas of CDT-related glycoforms and the sum of peak areas of all Tf glycoforms.

RESULTS

In most cases, good separations of Tf glycoforms were obtained. In the newborns the %CDT was 0.51 versus 0.66 in adults (difference not statistically significant). Trisialo-Tf concentration was significantly lower in newborns (3.20) than in adults (4.11). Furthermore, pentasialo-Tf appeared to be lower in newborns (7.30) than in adults (14.00), but because complete separation of the peaks of tetrasialo- and pentasialo-Tf was not always possible, this finding could not be confirmed statistically.

CONCLUSIONS

CZE showed definite advantages in terms of volume of blood to be collected, simplicity and standardization of analysis and, because of the direct detection of the separated zones, accuracy of quantification. The present study provides the basic information in the search for glycosylation defects in newborns.

Comparison of ethyl glucuronide in hair with carbohydrate-deficient transferrin in serum as markers of chronic high levels of alcohol consumption

This study was designed with the aim to compare sensitivity and specificity of ethyl glucuronide in hair (HEtG) and carbohydrate-deficient transferrin (CDT) in serum as markers of heavy drinking. Eighty-six volunteers, including teetotalers, social, and heavy drinkers, were interviewed to evaluate their ethanol daily intake (EDI) during the last 2-week and 3-month periods. HEtG determination was performed by a fully validated LC-MS-MS procedure and ranged from <LOD (2 pg/mg) to 890.5 pg/mg. CDT was measured by immunonephelometry or by HPLC. Sensitivity and specificity of the two markers as indicators of an EDI higher than 60 g/day were calculated, with cut-off at 27 pg/mg (HEtG) and 2.5% (CDT). Considering the EDI of the last 2 weeks, HEtG showed equal selectivity (0.93 for both HEtG and CDT-immunonephelometry; 0.70 for both HEtG and CDT-HPLC) and 2 times the sensitivity of either of the two CDT methods (1.00 vs. 0.44 for CDT-immunonephelometry; 0.96 vs. 0.50 for CDT-HPLC). The same difference in performances but with higher absolute sensitivity and selectivity values for HEtG were observed considering the EDI of the last 3-months (selectivity: 1.00 for both HEtG and CDT-immunonephelometry, 0.89 and 0.78 for HEtG and CDT-HPLC, respectively; sensitivity: 1.00 vs. 0.47 for CDT-immunonephelometry; 0.98 vs. 0.51 for CDT-HPLC). Our results indicate that HEtG, as compared to CDT measured using different methods, is a selective marker of ethanol heavy chronic use providing considerably higher sensitivity.

The hospitalized patient with abnormal liver function tests

Evaluation of abnormal liver function tests (LFTs) in the hospitalized patient is typically more urgent than the outpatient setting. This process is best organized into four steps. The first step is to determine whether the abnormal LFTs are associated with the illness resulting in the admission to the hospital or preceded the present illness. The second is to determine the etiology of the underlying liver disease. The third step is to evaluate the severity of the liver dysfunction and determine if acute liver failure (ALF) or acute decompensation of chronic liver failure is present. The final step is to look for the presence of associated complications-either those of ALF or chronic liver failure as appropriate.

Measuring carbohydrate-deficient transferrin by direct immunoassay: factors affecting diagnostic sensitivity for excessive alcohol intake

BACKGROUND

carbohydrate-deficient transferrin (CDT) is a marker of alcohol intake that is used for detecting or monitoring alcohol-use disorders. The introduction of a new direct immunoassay for CDT justifies reevaluation of test performance and reexamination of factors affecting test diagnostic sensitivity and specificity.

METHODS

individuals enrolled in twin/family studies of alcohol use and dependence provided blood samples and information on recent alcohol use. Serum CDT concentration was measured in 2 088 people with the N Latex CDT (Dade Behring) method, and CDT percentage (CDT%) was calculated as the proportion of the total transferrin concentration measured with Roche reagents.

RESULTS

diagnostic sensitivity was low, both for comparisons of men who reported an alcohol intake of >28 drinks/week vs those who consumed < or = 28 drinks/week (28% sensitivity) and for women who consumed >14 drinks/week vs those who consumed < or = 14 drinks/week (18% sensitivity), at cutoff values that yielded a 95% specificity. Body mass index, variables associated with metabolic syndrome, and smoking had notable effects on the probability of an abnormal CDT result with excessive alcohol use. Diagnostic sensitivity was greater in men of normal weight (43%) than in obese men (10%) and greater in male smokers (38%) than in male nonsmokers (21%). In women, diagnostic sensitivities were < or = 20%, even for those of normal weight and for smokers.

CONCLUSIONS

CDT is a poor marker of excessive alcohol intake in both women and men who are overweight or obese. It is also less useful in nonsmokers than in smokers. The diagnostic performance of the direct immunoassay and the effects of obesity and smoking are similar to those reported with previous anion-exchange immunoassay methods.

Forensic analysis of carbohydrate-deficient transferrin (CDT) by HPLC—Statistics and extreme CDT values

BACKGROUND

Carbohydrate-deficient transferrin (CDT) is the most specific serum marker of chronic alcohol abuse so far. There is little knowledge about extreme CDT values of >20% and the more >30% CDT.

METHODS

Serum CDT/transferrin ratios from 19,236 serum samples sent to our laboratory for routine CDT analysis were determined by HPLC. About 75% of these serum samples were from traffic or employment medicine investigations. A CDT value frequency histogram was computed and extreme CDT values were clinically validated.

RESULTS

Fourteen thousand four hundred and sixty-one CDT results were normal (< or =1.7%) and 4775 increased (1.8-36.9% CDT). Most frequent normal and increased results were 0.9% CDT (n=1964) and 1.8% CDT (n=356). CA. 70% of the pathological results were between 1.8% and 5.0% CDT, ca. 88% between 1.8% and 10.0% CDT, and 98% between 1.8% and 20.0%. CDT values >20.0% appeared in 79 cases and results >30.0% in two cases (33.8% and 36.9%). In each case of CDT values >20%, chronic alcohol abuse was the underlying cause as confirmed by anamnestic exploration.

CONCLUSIONS

CDT/transferrin ratios are usually <20%. Higher values can appear in rare cases. CDT results >30% can be due to alcohol abuse but should be considered as remarkable single observations. Visualization of the transferrin isoform patterns by HPLC allows the detection of pathological transferrin isoform patterns and of genetic transferrin variants. This is essential for a reliable interpretation of (extreme) CDT values. CDT analysis by immunoassays without physico-chemical confirmatory analysis is no longer acceptable.