Biological markers of alcohol consumption and effect of calcitonin in nonalcoholic men: a prospective, double-blind study

Are Commonly Ordered Lab Tests Useful Screens for Alcohol Disorders in Older Male Veterans Receiving Primary Care?

Although mean corpuscular volume (MCV), aspartate aminotransferase (AST), alanine aminotransferases (ALT), and the AST/ALT ratio are sometimes used as markers of alcohol disorders, their utility has not been established in older persons. We determined the tests' performance characteristics for (1) at-risk drinking, (2) CAGE positivity, (3) at-risk drinking and CAGE positivity, and (4) a clinician-recorded diagnosis of alcohol abuse/dependence in a study of older male veterans receiving primary care. Participants (n = 587) included patients who had MCV, AST, and/or ALT data collected as part of routine care no more than 12 weeks before or after enrollment. MCV, AST, and ALT test results were obtained from the VA's database. At enrollment, the Timeline Followback and Alcohol Use Disorders Identification Test (AUDIT) were used to identify at-risk drinkers (> or = 15 drinks per week or AUDIT score > or = 8), and the CAGE questionnaire was administered to identify participants with a history abuse/dependent drinking (CAGE score > or = 2). Participants' medical records were reviewed to identify subjects with a clinician-recorded diagnosis of alcohol abuse/dependence. The prevalence of abnormal test results for MCV (threshold value = > 98), AST (> 41), ALT (> 41), and the AST/ALT ratio (> 2) was 11%, 4%, 4%, and 5%, respectively. The occurrence of at-risk drinking, CAGE positivity, at-risk drinking and CAGE positivity, and a clinician-recorded diagnosis of alcohol abuse/dependence was 11%, 25%, 5%, and 9%, respectively. Test sensitivity ranged from 3.9% to 25.4% and specificity from 88.5% to 97.1%, whereas positive likelihood ratios varied from 0.72 to 4.01 and negative likelihood ratios from 0.82 to 1.04. Areas under the receiver operating characteristic curve were similar (range = 0.50-0.58) across tests. In conclusion, MCV, AST, ALT, and the AST/ALT ratio are not useful markers of alcohol disorders in older male veterans.

Alanine Aminopeptidase Activity in Urine: A New Marker of Chronic Alcohol Abuse?

BACKGROUND

The purpose of this study was to evaluate the activity of urinary alanine aminopeptidase (AAP), the enzyme released from the brush border membranes of renal proximal tubules, as a new biological marker of chronic alcohol abuse.

METHODS

The AAP activity was assayed and compared between a group of 76 alcoholics undergoing detoxification and a group of 37 alcoholics abstaining from alcohol for at least 6 weeks. In all patients, the enzyme activity was measured both in untreated urine (uAAP) and after removal of endogenous AAP inhibitors by molecular filtration on Sephadex (eAAP).

RESULTS

There was a correlation between the uAAP and eAAP activities in both groups of patients (r = 0.61 and r = 0.81 in abstinent alcoholics and in alcoholics undergoing detoxification, respectively), and both the uAAP activity and the eAAP activity were significantly and markedly higher in alcoholics being detoxified than in their abstinent counterparts. As revealed by receiver operating characteristic analysis, the discriminative power of the eAAP activity assay was higher than that of the uAAP activity assay. The area under the corresponding receiver operating characteristic curves was 0.84 +/- 0.04 and 0.78 +/- 0.05 (mean +/- SE), respectively.

CONCLUSIONS

The results of this study demonstrate that the assays of urinary AAP activity, which relate to the nephrotoxic effects of alcohol abuse, could be a valuable complement to the other presently used markers of chronic alcohol abuse that are generally based on ethanol hepatotoxicity. Compared with the uAAP activity test, the eAAP activity test is of clear diagnostic advantage.

The activity of beta-hexosaminidase (uHex) and gamma-glutamyltransferase (uGGT) in urine as non-invasive markers of chronic alcohol abuse: II. Opiate-dependent subjects receiving methadone substitution

The usefulness of beta-hexosaminidase (uHex) and gamma-glutamyltransferase (uGGT) activity in urine as markers of chronic alcohol abuse was examined in male methadone programme participants. The group consisted of 24 non-abusing and 21 alcohol-abusing men. It has been demonstrated that the uHex test is one of the best alcohol abuse markers for opiate-dependent individuals (Receiver Operating Characteristic (ROC) area under the curve (AUC) 0.82, sensitivity 0.70, specificity 0.82). The uGGT test can be used as a marker of alcohol abuse in opiate-dependent men, however, its parameters are worse than those of uHex (ROC AUC 0.73, sensitivity 0.71, specificity 0.77). Among serum markers, only the relative amount of carbohydrate-deficient transferrin (s%CDT) has parameters sufficient for diagnostic use (ROC AUC 0.74, sensitivity 0.60, specificity 0.86). Factors other than alcohol can render the commonly used sGGT and sHex tests useless (differences between means for abusing and abstinent patients were insignificant, AUC ROC were lower than 0.7-0.65 and 0.69, respectively). Their good parameters, low costs, ease of use and non-invasive character are all features which make uHex and uGGT highly useful tools in the detection of chronic alcohol abuse in opiate-dependent patients participating in a methadone substitution programme.

Comparison of HPLC and Small Column (CDTect) Methods for Disialotransferrin

Background: Current methods for determination of carbohydrate-deficient transferrin (CDT) are based on separation of the CDT fraction by ion-exchange chromatography on minicolumns and quantification by immunoassay. Alternatively, the transferrin isoforms can be separated by HPLC anion-exchange chromatography and quantified by absorbance. This method has been reported to improve the validity of CDT as a marker of chronic alcohol abuse.

Methods: HPLC on either MonoQ or ResourceQ anion-exchange columns was used to separate and quantify isoforms of transferrin with detection at 460 nm. The result was expressed as the percentage of the disialo form (pI 5.7) of total transferrin (DST). The commercial CDTectTM assay was used as a comparison method. Serum samples from nondrinkers (n = 57), moderate drinkers (n = 77), and heavy drinkers (n = 139) were analyzed.

Results: In ROC analysis for differentiation between moderate and heavy drinkers, the area under the curve (AUC) for the HPLC method was 0.87 (95% confidence interval, 0.81–0.93), whereas that for CDTect was 0.72 (95% confidence interval, 0.64–0.80). At 90% specificity, the sensitivity of DST was 63% (95% confidence interval, 53–73%) compared with 33% (22–44%) for CDT. The reference interval of the HPLC method was 0.68–1.7%.

Conclusions: The HPLC anion-exchange method for quantification of CDT provides substantially better separation between moderate and heavy drinkers than the CDTect method.

Carbohydrate-deficient transferrin as compared to other markers of alcoholism: a systematic review

This is a systematic review of the studies in which carbohydrate-deficient transferrin (CDT) has been compared to other laboratory markers in different experimental conditions, clinical settings, and populations. Only the studies (n = 54) in which CDT was compared either to the conventional or new biological markers of alcoholism, heavy drinking, or alcohol use were selected for further evaluation. Two prospective studies indicate that in men CDT is slightly more sensitive than gamma-GT in reflecting changes in these markers caused by drinking of a moderate and fixed amount of alcohol during three to four weeks. In one prospective study, in which the drinking history of male heavy drinking volunteers was as close the golden standard as possible; that is, obtained by a prospective anonymous drinking diary, CDT was slightly but not significantly better marker than conventional laboratory markers (ASAT, ALAT, gamma-GT and beta-Hex) in the identification of men drinking more than 400 g of alcohol daily. Similar prospective studies concerning women have not been done. Six prospective treatment outcome studies indicate that CDT may be a significantly more sensitive marker than gamma-glutamyltransferase (gamma-GT) in the detection of relapses in male alcoholics. However, these two tests can also be considered to be complementary markers. Furthermore, in the detection of relapses the baseline values of CDT and gamma-GT should be measured and compared on individual basis to the pretreatment values. Comparable data are not available from female alcoholics. In selective materials comprising male alcoholics and heavy drinkers, CDT was found to be a slightly more sensitive marker than gamma-GT in seven retrospective studies. In five studies, gamma-GT was slightly better. However, the differences between CDT and gamma-GT in general were not statistically significant. In three studies, the combined use of CDT and gamma-GT improved the sensitivity but with the expense of specificity. Only four studies included women and in three of these the sensitivity of gamma-GT was better than that of CDT, whereas in one study CDT was better than gamma-GT in the detection of female heavy drinkers. Seven studies performed in primary health care settings and among young populations demonstrate that the performance of CDT in the identification of heavy and problem drinkers in this type of populations is very low, although comparable to the poor performance of the conventional laboratory markers, too. According to seven studies, the sensitivity of gamma-GT is slightly better than that of CDT in the identification of excessive alcohol consumption among hospitalized male and female patients. However, in this type of hospital setting, the specificity of CDT is markedly higher than that of gamma-GT. There is some evidence indicating that the performance of the tests can be improved with the combined use of both tests. Eight studies indicate that both in men and women CDT is a better marker than gamma-GT in the identification of alcohol abuse among patients with alcoholic and nonalcoholic liver diseases. This is mostly due to the higher specificity of CDT as compared to that of gamma-GT.