Estimation of alcohol intake from laboratory results

Erythrocyte mean cell volume--correlation to drinking pattern in heavy alcoholics

Erythrocyte mean cell volume (MCV) correlates well to alcohol intake in moderate alcoholism, but only about 50% of heavy drinkers have increased MCV. To evaluate the influence of the duration and extent of a drinking episode on MCV, 64 addictive alcoholics were investigated prospectively within two weeks after a drinking period. Their daily alcohol intake was 120-480 g and the actual drinking period has lasted for 1-104 weeks. For comparison, 21 non-active alcoholics were investigated. There was no correlation between MCV of active alcoholics and daily alcohol consumption or smoking habits, whereas a significant positive correlation was found between MCV and both duration of actual drinking episode and total alcohol intake in this period. We conclude that MCV is probably of greater value in estimating the duration and extent of actual drinking episodes in heavy alcoholics than in screening for alcoholism.

Net influx and efflux of 22Na in erythrocytes from normotensive offspring of patients with essential hypertension

Fresh erythrocytes from 35 young normotensive individuals (20 males), the offspring of patients with essential hypertension (EH), and from 24 normotensive controls (14 males) were incubated at 37 degrees C in an isotonic buffer with 22Na. After 80 min, the net influx (net accumulation) of 22Na was not significantly different in either group, but after 140 min it was significantly higher (8.2%, p less than 0.01) in erythrocytes from male offspring as opposed to male controls. After both 80 and 140 min of incubation, the net influx of 22Na was significantly higher in males than in females in the respective groups. During a 60-minute period the net efflux of 22Na from preincubated (180 min) erythrocytes in 14 males in the offspring group was not significantly different from that found in 10 male controls. These findings could indicate that little differences exists in vitro between offspring and controls in the undirectional fluxes across the membrane. The difference between the male groups in the net influx after 140 min could indicate a higher Na content in the intracellular space in the offspring group, as assumption subsequently verified in a follow-up. The net influx of 22Na after 140 min was significantly correlated (R=0.58, p less than 0.05) to total plasma aldosterone male controls, but not in the offspring. No differences in the mean concentrations of total aldosterone, plasma and urinary electrolytes or in serum gamma glutamyl transferase were noted between offspring and controls. Abnormal cellular handling of sodium at least in the male offspring of patients with EH for at least two generations may be an important predisposing factor for EH.

Gamma glutamyl transferase

Serum gamma-glutamyl transferase (GGT) has been widely used as an index of liver dysfunction and marker of alcohol intake. The last few years have seen improvements in these areas and advances in understanding of its physiological role in counteracting oxidative stress by breaking down extracellular glutathione and making its component amino acids available to the cells. Conditions that increase serum GGT, such as obstructive liver disease, high alcohol consumption, and use of enzyme-inducing drugs, lead to increased free radical production and the threat of glutathione depletion. However, the products of the GGT reaction may themselves lead to increased free radical production, particularly in the presence of iron. There have also been important advances in the definition of the associations between serum GGT and risk of coronary heart disease, Type 2 diabetes, and stroke. People with high serum GGT have higher mortality, partly because of the association between GGT and other risk factors and partly because GGT is an independent predictor of risk. This review aims to summarize the knowledge about GGT's clinical applications, to present information on its physiological roles, consider the results of epidemiological studies, and assess how far these separate areas can be combined into an integrated view.

Enzymes and circulating proteins as markers of alcohol abuse

The identification of alcohol abuse is an important social and clinical objective for which various biochemical procedures have been utilized, serum enzymes and circulating proteins being predominant. Tests are required to detect alcohol abuse as screening procedures in the general population as well as for the specific diagnosis of those presenting as hospital inpatients or outpatients, especially when liver disease is present or suspected. The amino-transferases are of limited value, although the mitochondrial isoenzyme of aspartate amino-transferase has been strongly advocated and is quite useful in detecting alcoholics among patients with liver disease. Gammaglutamyl transferase, by contrast, is raised in all forms of liver disease but can identify 30-50% of those consuming excessive amounts of alcohol before organic damage becomes manifest. Serum carbohydrate-deficient transferrin (CDT) is raised in many alcohol abusers without and most with liver damage, but is rarely elevated in other forms of liver disease. Haemoglobin-associated acetaldehyde, the newest biochemical index to be evaluated in alcoholics, is one of several adducts formed by the reaction of acetaldehyde with various proteins, and antibodies to these adducts may contribute, at least in part, to immunological tissue damage provoked by chronic excessive consumption of alcohol. Its assay is technically complex and it appears to be present in higher concentrations in heavy drinkers than in those who fulfill the criteria of addictive alcohol abuse. Many other markers have been introduced in the last decade but the search for a reliable index continues. CDT comes closest at the present time to matching the desired specificity, although it is of limited value in screening unselected non-hospitalized subjects.

Screening for alcoholism in a psychiatric hospital

The prevalence of alcoholism is generally underestimated in patients in private practices, general hospitals and psychiatric institutions. Even though the World Health Organization has advocated the concurrent use of laboratory test results and questionnaires for screening, these methods are seldom used together. In this study, patients admitted consecutively to the North Bay Psychiatric Hospital were screened for alcoholism using the Michigan Alcoholism Screening Test (MAST) and gamma-glutamyl-transferase plasma level. Unexpectedly, 56.7% of the entire sample were identified as possible alcoholics; of these, 73.5% were men and 26.5% were women. When rates for men and women were looked at separately, it was found that 66.2% of the men and 40.6% of the women were alcoholic. Participants who tested positive on one or both of the screening tests were offered a more complete evaluation of their drinking behaviour. A diagnosis of alcoholism was confirmed in 88.2% of the patients who agreed to participate further. The question remains whether the high prevalence rates found are a function of the particular sample studied (i.e., patients in a hospital which typically serves a socially disadvantaged sector of the population) or reflects a feature of the general population in this catchment area. A study is currently underway in general hospitals of North Eastern Ontario in an attempt to answer this question.

Heavy drinking among Norwegian male drunken drivers: a study of gamma-glutamyltransferase

The distributions of blood alcohol concentrations (BACs) of different age groups of drunken drivers suggested that a large number of the drunken drivers above 29 years of age had high tolerance to alcohol, and many of these might be heavy drinkers. In order to study the extent of heavy drinking, gamma-glutamyltransferase (GGT) activities were measured in 269 blood samples from male drunken drivers using a new method suitable for hemolyzed blood samples. Of the drunken drivers above 29 years of age, 40% had elevated GGT activities, indicating that roughly one-third of these drivers might be heavy drinkers (consuming more than 80 g of alcohol/day). Of the drunken drivers above 29 years of age with BACs above 55 mmol/liter (250 mg/100 ml), 63% had elevated GGT, indicating that a large majority of these drivers were heavy drinkers. Fewer of the younger drivers had elevated GGT activities. The GGT activities of the repeating offenders indicated that the percentage of heavy drinkers in this group was approximately the same as in the total population of apprehended drunken drivers.

The Tromsø Heart Study: distribution of, and determinants for, gamma-glutamyltransferase in a free-living population

Gamma-glutamyltransferase (GGT) was measured in 1579 men, aged 20-54 years, and 1654 women, aged 20-49 years, screened for coronary risk factors. The distribution was right-skewed with medians 15 and 10 U/l for men and women, respectively. Less than 3.8% of the men and 0.8% of the women had GGT greater than or equal to 50 U/l. The low level of GGT matched well with the low mortality of cirrhosis and the modest use of alcohol in Norway. Multiple regression analysis for each sex showed a strong positive association with body mass index, use of alcohol and, unexpectedly, a negative association with coffee consumption, whereas serum triglycerides and the time since the last meal showed a weaker positive association. In women, use of oral contraceptives was positively associated with GGT.

Whole body measurements of sodium turnover in offspring of patients with sustained essential hypertension

The elimination rate (percent per day) of injected 22Na using a whole body measurement technique was significantly lower (5.8 +/- 1.5) in normotensive or borderline hypertensive offspring of essential hypertensive patients than in 15 age- and sex-matched, normotensive controls (7.3 +/- 1.0). There were no significant differences in exchangeable sodium, whole body potassium or in the urinary excretion of sodium, potassium and creatinine. The basis for the difference in turnover rate during week 1 is probably an alteration in the cellular handling of sodium (i.e. increased intracellular sodium) in the still normotensive offspring of patients with essential hypertension. The long-term (more than 100 days) whole body retention of 22Na was found to be only 0.1% of that injected, which justifies the use of this method on larger population groups.

Serum gamma-glutamyl transferase and a somatic health score in middle-aged men

In an ongoing population investigation of middle-aged men in Malmö, Sweden, several health screening variables showed strong but crude individual covariations with the level of the hepatic enzyme, serum gamma-glutamyl transferase (GGT). These variables were combined, according to an analysis of their normal distributions, into a score index which exhibited a much smoother correlation with low, normal, and elevated levels of GGT when tested in a random population subsample. It is concluded that this scoring system may find further utilisation as a general descriptive method of recording statistical covariations between health screening tests and sum them up.

Structural, functional, and clinical aspects of gamma-glutamyltransferase

GGT catalyses the transfer of gamma-glutamyl residues to amino acids or small peptides. A number of publications report the purification of GGT, the rat kidney enzyme being the best characterized. Bromelain treatment liberates an active form with a molecular weight of 68,000 separable into two nonidentical glycopeptides with molecular weights of 46,000 and 22,000; the latter contains the gamma-glutamyl binding site. GGT is intimately concerned in the synthesis and metabolism of glutathione through the gamma-glutamyl cycle. There is good evidence that this plays a role in the absorption of amino acids from the glomerular filtrate and from the intestinal lumen through a translocation mechanism. Many studies indicate that the GGT content of liver is increased by enzyme-inducing drugs and that this increase is reflected in elevated activity of the enzyme in blood serum. The serum assay has potential in monitoring drug compliance. Increased serum GGT activity encountered in chronic alcoholics seems to be partly due to microsomal enzyme induction. Utility of the assay in detecting alcoholism is controversial, but it is a useful index to compliance with therapy. Dramatic increases in activity are found in many chemically-induced animal tumors, and can be recognized in premalignant cells long before any morphological changes become evident. It has been used as a test for hepatic metastases, but its predictive value has shown a wide range in the hands of many authors. A similar controversy applies to its role in monitoring cancer therapy. Many synthetic substrates have been used to measure serum GGT activity. Currently, L-gamma-glutamyl-p-nitroanilide is the most popular. Males have higher values than females; activity is very high in the neonate and rather low in pregnancy. The most universal application of serum GGT assay is in diagnosis of liver and biliary tract disease. It is widely believed that higher values occur in biliary obstruction than in parenchymal disease. However, the percentage incidence of abnormalities and the overlap of values in individual cases in different disease categories are so great that the enzyme cannot be recommended for this purpose. Isoenzyme analyses have been performed in an attempt to improve the diagnostic specificity of the serum GGT assay. Tissue-specific patterns have not been described, and disease-specific patterns cannot be reproduced with confidence. Whereas exciting advances are being made in understanding the molecular structure, mechanism, and functions of the enzyme it has yet to find a genuinely useful diagnostic role substantiated by a convincing body of scientific data.

Estimation of alcohol intake from laboratory results

Subjects with abnormalities in a number of laboratory tests were shown to have higher than usual probabilities of being heavy drinkers. Quantitative estimates have been made of the probabilities of heavy drinking from the results of the following tests: gamma-glutamyl transpeptidase, mean corpuscular volume, uric acid, triglyceride, and aspartate aminotransferase. In men, but not in women, there was a clear increase in this probability with increasing test results for these five tests, which may prove useful in the detection of individuals who are at risk from their drinking habits.