Carbohydrate-deficient transferrin--a valid marker of alcoholism in population studies? Results from the Copenhagen City Heart Study

Semiautomated procedures for evaluation of carbohydrate-deficient transferrin in the diagnosis of alcohol abuse

Carbohydrate-deficient transferrin (CDT) may now be the most valuable biological marker for diagnosis of alcohol abuse. We compared the diagnostic performance of two new CDT tests, Axis %CDT turbidimetric immunoassay (TIA) and Axis %CDT HPLC, against Specialty Laboratories’ isoelectric focusing/immunoblotting/laser densitometry (IEF/IB/LD). Both Axis tests include one-half the concentration of trisialotransferrin isoforms in their CDT quantitation schemes. Considering an alcohol abuse prevalence of 7%, Axis %CDT TIA shows a sensitivity of 87% at 98% specificity and a positive predictive value (PPV) of 0.75; %CDT HPLC shows a sensitivity of 87% at 100% specificity for a PPV of 1, and the IEF/IB/LD shows 81% sensitivity at 94% specificity for a PPV of 0.5. All three CDT tests show the same negative predictive value (0.98). Both Axis procedures perform better than IEF/IB/LD in the diagnosis of alcohol abuse; %CDT TIA is available in several semiautomated, cost-effective formats.

Carbohydrate-deficient transferrin and alcohol dependency: variation in response to alcohol intake among different groups of patients

Carbohydrate-deficient transferrin (CDT) and gamma-glutamyltransferase (GT) were evaluated as markers of alcohol dependency in two different groups of patients. Sensitivity of CDT was nearly 75% for patients hospitalized for detoxification, but lower than 50% for alcohol-dependent patients admitted to acute surgery. CDT correlated with self-reported alcohol consumption in both groups, and sensitivity increased with higher alcohol intake. Sensitivity of CDT for females in both groups was considerably lower than for males, although their alcohol consumption was not significantly different. Serum activity of GT showed almost identical performance as CDT when evaluated by receiver-operating characteristics curve analysis (ROC-analysis), but sensitivity and specificity of the two markers varied differently with both alcohol consumption and age. Among the surgical patients, the highest sensitivity of CDT was found for the middle-aged patients (36 to 50 years), whereas the highest sensitivity of GT was found for the eldest. A tendency for similar age-related differences were also observed among the patients warded for detoxification, but these differences were not statistically significant. A particular difference between the two groups was noted among the youngest patients (21 to 35 years), with a very low sensitivity of CDT (< 20%) for the surgical patients and a high sensitivity (77%) for the detoxification group. This difference was not only caused by differences in the present alcohol consumption, but would also be related to differences in drinking pattern or duration. Two commercial kits analyzing CDT were compared and ROC-analysis indicated identical performance of the two. However, a kit determining CDT as percentage of total transferrin showed a somewhat higher sensitivity among patients with low serum transferrin. We conclude that CDT and GT show variant responses to alcohol consumption in different groups of patients. The level of the two markers are related to sex, age, and alcohol consumption. Furthermore, the performance of both markers depend on the patients' history of alcohol abuse. CDT and GT are statistically independent markers and may therefore supplement each other.

Increased serum concentration of carbohydrate-deficient transferrin in patients with combined pancreas and kidney transplantation

Serum concentration of carbohydrate-deficient transferrin (cCDT) is used for laboratory diagnosis and follow-up of chronic alcohol abuse. In analyzing by CDTect-RIA (Pharmacia) sera from outpatients with combined pancreas and kidney transplantation and no excessive alcohol consumption, we found above-normal values for cCDT and CDT/transferrin ratios (CDT/Tf) in more than half of the samples. Isoelectric focusing of these samples showed distinct bands of carbohydrate-deficient isotransferrins, supporting the abnormal findings from the CDTect assay. In contrast, diabetics and outpatients who had received only kidney transplants showed normal values for cCDT, CDT/Tf, and isotransferrin patterns. Increased serum Tf, sialidase-producing microorganisms, and immunosuppressive medication were eliminated as causes of these abnormal cCDT and CDT/Tf results. Successful pancreas transplantation leads to hyperinsulinemia and normoglycemia, in contrast to hypoinsulinemia and hyperglycemia in the patients who receive kidney transplants alone. These factors may have pathogenic importance for CDT increase, yielding results falsely interpreted as positive with respect to alcohol abuse in patients with combined pancreas and kidney transplantation.

Carbohydrate deficient transferrin (CDT) in alcoholic cirrhosis: a kinetic study

BACKGROUND/AIMS

Carbohydrate deficient transferrin has been introduced as a marker of excessive alcohol intake. The present study was undertaken in order to measure the circulating level of carbohydrate deficient transferrin in patients with alcoholic cirrhosis and to assess arteriovenous kinetics of carbohydrate deficient transferrin in liver and kidney.

METHODS/RESULTS

The median value of serum carbohydrate deficient transferrin was 16.0 U/l in patients with alcoholic cirrhosis (n = 41), and this value was not significantly different from that of a normal control group (median 17.4 U/l, n = 55, ns). Carbohydrate deficient transferrin was significantly higher in patients with cirrhosis and high current alcohol intake than in abstaining patients (20 vs. 14 U/l, p < 0.05). Similarly, controls with a high current alcohol intake (> 50 g/day) had a significantly higher carbohydrate deficient transferrin concentration than controls with a low alcohol intake (< 10 g/day) (36 vs. 14.9 U/l, p < 0.005). No significant differences were detected between carbohydrate deficient transferrin in artery and liver vein or artery and renal vein, either in patients with alcoholic cirrhosis (n = 11) or in controls (n = 8), which indicates a slow turnover rate of carbohydrate deficient transferrin. Food ingestion did not affect the circulating level of carbohydrate deficient transferrin, and the analysis of carbohydrate deficient transferrin was almost unaffected by the presence of ethanol in plasma within the biological range (ethanol 0-100 mmol/l).

CONCLUSIONS

Our results suggest that measurement of carbohydrate deficient transferrin may be used in patients with alcoholic cirrhosis. High current alcohol intake is associated with higher carbohydrate deficient transferrin levels than in those with low alcohol intake, but the overlap is substantial in patients with cirrhosis. Carbohydrate deficient transferrin has a low turnover rate in both patients with cirrhosis and normals.

Carbohydrate-deficient transferrin and gamma-glutamyl transferase levels during disulfiram therapy

Serum samples for quantification of carbohydrate-deficient transferrin (CDT) and gamma-glutamyl transferase (GGT) were collected from alcohol-dependent men and women upon admission to the hospital for detoxification, and repeatedly over a 3- to 5-week period of supervised disulfiram administration as outpatients. On admission, 10 of 12 patients showed CDT concentrations above the conventional cutoff limits, whereas 6 had elevated GGT values. Normalization usually occurred within 1 to 3 weeks of disulfiram treatment, after which CDT and GGT leveled out at a relatively stable individual baseline level. However, in those patients with the highest values on admission, the decline continued during the entire observation period. The time for normalization of GGT was typically longer than for CDT. In four male patients who had taken disulfiram regularly (400-800 mg every second or third day) for at least 3 months before entering the study, the CDT and GGT concentrations were stable over time and all fell within normal limits. The present results indicate that disulfiram treatment does not influence the serum level of CDT. It is also suggested that consecutive CDT and GGT measurements during outpatient treatment with disulfiram after detoxification can be used to identify the individual baseline (i.e., abstinence) values for CDT and GGT, and, furthermore, for monitoring treatment outcome.

Carbohydrate-deficient transferrin in healthy women: relation to estrogens and iron status

The determination of carbohydrate-deficient transferrin (CDT) in serum has been found useful as a marker of increased alcohol consumption of > 60 g/day. It is not clear why the reference range is different for women (0 to 26 units/liter) and men (0 to 20 units/liter). We evaluated serum CDT in 286 healthy subjects (209 women, 77 men) using a commercially available radioimmunoassay. Premenopausal women had higher CDT levels than postmenopausal women, whereas no age-related difference of CDT levels was found in men. In postmenopausal women, higher CDT levels were associated with estrogen replacement therapy. In premenopausal women, however, neither the phase of the menstrual cycle nor contraceptive steroid use showed a significant association with the increase in CDT levels. No significant correlations were found between CDT and either serum estradiol or serum iron. In conclusion, both premenopausal state and postmenopausal estrogen replacement therapy seem to increase serum levels of CDT. Therefore, menopausal status and exogenous estrogens should be considered when interpreting CDT values in women.

Sensitivity and specificity of carbohydrate-deficient transferrin as a marker of alcohol abuse are significantly influenced by alterations in serum transferrin: comparison of two methods

Despite a number of investigations suggesting the value of carbohydrate-deficient transferrin (CDT) as a marker of alcohol abuse, a variety of issues on the applicability of CDT measurements in clinical settings have remained unexplored. Earlier studies in this field have focused on the relationship of CDT and the amount of alcohol consumption or presence of liver disease, whereas the influence of alterations in serum transferrin concentrations on CDT has received less attention. In this study, we compared two different methods for measuring CDT (CDTect and %CDT) and total transferrin concentrations in a sample of 83 alcohol abusers (20 patients with alcoholic liver disease and 63 heavy drinkers who were devoid of liver disease, despite excessive alcohol consumption) and 89 controls, who were social drinkers or abstainers. The control population included 53 hospitalized patients with expected abnormalities in serum transferrin concentrations caused by conditions such as negative iron balance, pregnancy, or nonalcoholic liver disease. Both methods gave significantly higher values in alcohol abusers than in controls (p < 0.01), but the overall sensitivity for detecting alcohol abuse was clearly higher for CDTect (59%) than for %CDT (34%). The correlation between the results obtained by the two methods (r = 0.629) significantly improved, when the CDTect values were replaced by the ratio of CDTect/total transferrin (r = 0.770) (p < 0.05). There was a positive correlation between the CDTect and serum transferrin (r = 0.201, p < 0.01), which was significant both in the alcoholics (r = 0.240, p < 0.05), and especially in the controls (r = 0.727, p < 0.001). A significant inverse correlation emerged between %CDT and total transferrin (r = -0.302, p < 0.01). The sensitivities of CDTect and %CDT for correctly classifying alcohol abusers in the subgroup of alcoholic liver disease patients were 90% and 70% and in the subgroup of heavy drinkers without liver disease (49% and 22%), respectively. Specificities for CDTect and %CDT in this sample were 81% and 100%, respectively. However, in the subgroup of hospitalized control patients with abnormal serum transferrin, the specificity of CDTect was only 48%. According to present data, CDTect seems to be more sensitive than %CDT for detecting alcohol abuse. However, any alteration in serum total transferrin concentration markedly decreases the assay specificity. This should be considered when interpreting the assay results in patients with elevated serum transferrin, such as iron deficiency, pregnancy, or liver diseases.