The distribution of serum alanine aminotransferase levels in a blood donor population

African Americans Demonstrate Significantly Lower Serum Alanine Aminotransferase Compared to Non-African Americans

BACKGROUND AND AIMS

Normal ranges of serum alanine aminotransferase (ALT) may vary by race. However, results from research studies are contradictory, and many of these studies have included only small numbers of African Americans. We investigated ALT values in patients without evidence of liver disease to determine whether normal ranges differ across race groups. We also evaluated whether a race- and sex-dependent upper limit of normal (ULN) would improve the ability of ALT to predict liver disease compared to the sex-dependent ULN currently in use.

METHODS

We identified ICD9 codes for liver conditions and diabetes in medical records from a sample of 6719 patients. Analysis of variance (ANOVA) was used to assess differences in ALT log-transformed distributions by race. Logistic regression was used to evaluate whether the addition of race to the current sex-dependent ULN improves the ability of ALT to predict liver disease (assessed by area under the receiver operating characteristic curve (AUROC)).

RESULTS

Among 1200 patients with BMI 18.5 < 25 and no evidence of liver disease or type 2 diabetes in their medical record, African Americans demonstrated significantly lower ALT (23.47 IU/L; 95% CL 22.87-24.10) than a combined group of Asian American/White/Other patients (25.71 IU/L; 95% CL 24.69-26.77). This difference remained across BMI categories. The race- and sex-dependent model demonstrated significantly better predictive ability than the sex-dependent model (AUROC = 66.6% versus 59.6%, respectively; p < 0.0001).

CONCLUSIONS

In a large, racially diverse sample, African Americans demonstrated significantly lower ALT compared to non-African Americans; this difference remained as BMI increased. The establishment of race-specific normal ranges for ALT could contribute to better screening and care for African American patients.

Alanine aminotransferase-old biomarker and new concept: a review

Measurement of serum alanine aminotransferase (ALT) is a common, readily available, and inexpensive laboratory assay in clinical practice. ALT activity is not only measured to detect liver disease, but also to monitor overall health. ALT activity is influenced by various factors, including viral hepatitis, alcohol consumption, and medication. Recently, the impact of metabolic abnormalities on ALT variation has raised concern due to the worldwide obesity epidemic. The normal ranges for ALT have been updated and validated considering the metabolic covariates in the various ethnic districts. The interaction between metabolic and demographic factors on ALT variation has also been discussed in previous studies. In addition, an extremely low ALT value might reflect the process of aging, and frailty in older adults has been raised as another clinically significant feature of this enzyme, to be followed with additional epidemiologic investigation. Timely updated, comprehensive, and systematic introduction of ALT activity is necessary to aid clinicians make better use of this enzyme.

Alanine aminotransferase is associated with metabolic syndrome independently of insulin resistance

BACKGROUND

Few studies have examined the effect of insulin resistance on the association between alanine aminotransferase (ALT) and metabolic syndrome. The association between ALT levels and metabolic syndrome were determined, independently of insulin resistance in Korean populations.

METHODS AND RESULTS

The association between ALT and metabolic syndrome were examined in 28,456 subjects who visited 7 Health Promotion Centers at University Hospitals in Korea from 2006 to 2008. HOMA-IR index was used to represent insulin resistance index. ALT levels were found to be positively associated with metabolic syndrome after adjusting for age, alcohol intake, and smoking status. Furthermore, when additional adjustment was made for insulin resistance, this association between ALT and metabolic syndrome, although slightly attenuated, remained strongly significant. Subjects in the highest ALT quartile were found to have a higher risk of having metabolic syndrome than those in the lowest quartile (odds ratio (OR)=4.45, 95% confidence interval (CI)=3.96-4.99 for men and OR=3.51, 95%CI=2.73-4.52 for women). In addition, the association between ALT level and the risk of metabolic syndrome was significantly higher in the relatively low risk group.

CONCLUSIONS

ALT levels were found to be significantly associated with metabolic syndrome independently of insulin resistance and with an interaction by age. Further cohort studies are needed to determine the usefulness of ALT levels for predicting the risk of metabolic syndrome.

Liver affection in iron overload studied with serum ferritin and serum aminotransferases

Liver dysfunction as measured by S-ALAT activity was present in 72% of patients over 40 years of age with HLA-related iron overload, mainly detected by laboratory screening. Liver dysfunction was correlated to the amount of iron stored (r = 0.54, p less than 0.001). When iron was removed by phlebotomy, liver function returned to normal. S-ALAT activity was closely correlated to serum ferritin concentration (r = 0.73, p less than 0.001). Even a mild iron excess can affect hepatocytes and result in increased levels of ferritin and aminotransferases in serum. Patients with "transaminitis" should be investigated for iron overload.

Association of elevated alanine aminotransferase with BMI and diabetes in older veteran outpatients

AIMS

We determined age-stratified associations of elevated alanine aminotransferase (ALAT), as a likely indicator of non-alcoholic steatonecrosis (NASH), with body mass index (BMI) and diabetes among older male, veteran outpatients.

METHODS

Administrative files at three, urban Veteran Administration Healthcare Systems were surveyed. 47.916 male outpatients, mean age 69.2 years, without ICD-9CM documented liver diseases or alcohol- or drug-abuse, had the highest of one or more ALAT results analyzed. Logistic regression determined age-stratified predictors of elevated ALAT among groups <50 ("younger-aged"), 50-70 ("middle-aged") and >70 ("older-aged"). BMI, diabetes and "statin" use were predictors.

RESULTS

1272 (2.7%) patients had their highest ALAT greater than the upper limit of normal (mean=98.4U/L). 4.9% of all diabetics and 15.2, 6.1 and 3.4% of the "younger-aged", middle-aged" and "older-aged" diabetics, respectively, had elevated ALATs. BMI values from 25 to <30 and 30 to 45, compared with those from >20 to <25, predicted elevated ALAT in the two younger groups. In contrast, among "older-aged" patients, diabetes independently predicted elevated ALAT, whereas BMI did not.

CONCLUSIONS

The cross-sectional findings support previous epidemiologic data associating ALAT elevations with obesity and diabetes, and provide new evidence that in elderly male patients, ALAT elevations, absent other known liver diseases, may selectively associate with diabetes.

Effect of gamma irradiation on blood from glucose 6 phosphate dehydrogenase deficient blood donors

Recently, the irradiation of cellular blood components has received increased attention. Normal red blood cells (RBC) when subjected to gamma irradiation show increase in haemolysis and increased storage lesions. Glucose 6 phosphate dehydrogenase (G6PD) deficient blood is lacking in anti-oxidant properties which protect the RBC membrane and therefore when subjected to gamma irradiation, it may lead to increased haemolysis. In this study, 500 healthy non-remunerated blood donors were screened for G6PD deficiency. About 350 ml of whole blood was collected from 10 G6PD deficient donors (cases) and 10 units were collected from donors who were not deficient for G6PD (controls). All units were subjected to gamma irradiation of 25 Gy by a self contained gamma cell irradiator (Nordion Canada) on day 0 and then stored at 4 degrees C. Sampling was done from these cases and controls on day 0, 7, 14 and 21. Estimation of free plasma hemoglobin (Hb), free plasma potassium (K) and lactate dehydrogenase (LDH) was performed. It was found that there were no significant changes between the cases and controls in any of the parameters assessed, although the values for all the parameters were higher in case group at the end of storage period, these differences were not statistically significant.

Dynamics of alanine aminotransferase during hepatitis C virus treatment

Studies of the kinetics of hepatitis C virus (HCV) decline during interferon (IFN)-based therapy have led to insights into treatment efficacy. However, the kinetics of serum alanine aminotransferase (ALT), an enzyme used as a surrogate of liver damage, have not been closely monitored, and it is not known if they correlate with those of HCV RNA. Here we describe the associations between ALT and HCV dynamics. We analyzed 35 patients treated daily with 10 mIU IFN-alpha 2b with or without ribavarin for 28 days followed by standard IFN/ribavirin therapy. Patients exhibited 4 patterns of ALT change: (1) exponential decay of ALT, (2) transient increase in ALT followed by a decrease to pretreatment or normal levels, (3) increase in ALT to a new level, and (4) no significant change. By simultaneously modeling HCV and ALT dynamics, we successfully fit the observed changes. We found ALT decays with t(1/2) = 12.7 hours. The transient increase in ALT observed in some patients suggested a mild hepatotoxic effect of IFN. However, patients with a smaller initial ALT increase achieved higher rates of viral negativity by week 72 (P =.02). The week-4 ALT decline correlated with the HCV log drop (P =.006) and the efficacy of therapy (P =.025). In conclusion, our results suggest the use of ALT as a surrogate marker for treatment effect in patients with elevated ALT.

Subjects positive for hepatitis C virus RNA with normal aminotransferase levels, a "trompe l'oeil" clinical picture?

BACKGROUND

Quite often subjects affected by chronic hepatitis C virus infection have no clinical signs of liver disease and serum aminotransferase values never go beyond the upper limit of normal. Yet these subjects, defined "asymptomatic HCV carriers", often have active viral replication and various degrees of histological damage.

AIMS

To verify, in a population of antibody to hepatitis C virus carriers, if normal serum aminotransferase values in hepatitis C virus-RNA positive differed considerably from those in hepatitis C virus-RNA negative subjects.

SUBJECTS/METHODS

We followed 24 anti-hepatitis C virus-positive subjects (15 hepatitis C virus-RNA positive and 9 negative) by measuring alanine and aspartate aminotransferase levels at 3-month intervals for a median of 40 months (range 6-77).

RESULTS

Determinations resulted repeatedly and rigorously within the normal range in all participants. Alanine aminotransferase values were higher in hepatitis C virus-RNA positives than in negatives (mean +/- SD: 0.609+/-0.172 vs 0.434+/-0.153 times the upper limit of normal; p<O.001). Aspartate aminotransferase values in both groups reflected the same consistent difference (mean +/- SD: 0.652+/-0.170 vs 0.528+/-0.151 times the upper limit of normal, p<0.001).

CONCLUSIONS

Our findings demonstrate that biochemical activity exists in asymptomatic hepatitis C virus-RNA-positive carriers, but it is so slight that serum aminotransferase levels do not go beyond the upper limit of normal. With the prevailing range of normality, serum aminotransferase determination is a helpful but not reliable marker of disease activity in chronic hepatitis C virus infection. The normal range for aminotransferases needs to be redefined in order to set up a more accurate diagnostic profile of subjects with chronic hepatitis C virus infection.

Elevated alanine aminotransferase (ALT) in blood donors: an assessment of the main associated conditions and its relationship to the development of hepatitis C

The determination of aminotranferases levels is very useful in the diagnosis of hepatopathies. In recent years, an elevated serum ALT level in blood donors has been associated with an increased risk of post-transfusion hepatitis (PTH). The purpose of the study was to research the factors associated with elevated ALT levels in a cohort of voluntary blood donors and to evaluate the relationship between increased ALT levels and the development of hepatitis C (HCV) infection. 166 volunteer blood donors with elevated ALT at the time of their first donation were studied. All of the donors were questioned about previous hepatopathies, exposure to hepatitis, exposure to chemicals, use of medication or drugs, sexual behaviour, contact with blood or secretions and their intake of alcohol. Every three months, the serum levels of AST, ALT, alkaline phosphatase, gamma glutamyl transpeptidase, cholesterol, triglyceride and glycemia are assessed over a two year follow-up. The serum thyroid hormone levels as well as the presence of auto-antibodies were also measured. Abdominal ultrasound was performed in all patients with persistently elevated ALT or AST levels. A needle biopsy of liver was performed in 9 donors without definite diagnostic after medical investigation. The presence of anti-HCV antibodies in 116 donors were assayed again the first clinical evaluation. At the end of follow-up period (2 years later) 71 donors were tested again for the presence of anti-HCV antibodies. None of donors resulted positive for hepatitis B or hepatitis C markers during the follow-up. Of the 116 donors, 101 (87%) had persistently elevated ALT serum levels during the follow-up. Obesity and alcoholism were the principal conditions related to elevated ALT serum levels in 91/101 (90.1%) donors. Hypertriglyceridemia, hypercholesterolemia, hypothyroidism and diabetes mellitus also were associated with increased ALT levels. Only 1/101 (0.9%) had mild chronic active non A-G viral hepatitis and 3/101 (2.9%) had liver biopsy with non-specific reactive hepatitis. The determination of ALT levels was not useful to detect donors infected with HCV at donation in Brazil, including the initial seronegative anti-HCV phase.

[Increase of aminotransferases]

Elevated aminotransferases activities are frequent in medical practice. In acute elevations, the mains causes are generally easily found (viral, drug-induced, toxic, ischemic). In moderate or prolonged elevations, the most frequent causes are steatosis (alcoholic, diabetes, obesity) and chronic hepatitis (viral B, D, C, drug-induced and auto-immune diseases.

U.K. multicentre study on blood donors for surrogate markers of non-A non-B hepatitis. Part I: Alanine transferase and anti-HBc testing

Blood samples from 9,215 blood donors in three U.K. centres (North London, Bristol and Manchester) were tested for their alanine aminotransferase (ALT) level and the presence of anti-HBc and anti-HCV. This paper presents the results of the ALT and anti-HBc tests. The prevalence of ALT > 45 IU/l was 3.1% overall (North London 3.06%, Bristol 4.56% and Manchester 1.97%). Manchester results were skewed by the methodology used for ALT measurement, highlighting the need for standard test methods. Anti-HBc was detected using the Wellcome enzyme-immunosorbent assay (EIA) and confirmatory testing was performed using a radioimmunoassay (RIA) and the Corecell haemagglutination assay. Repeat reactive rates were 0.9, 0.79 and 0.94% for North London, Bristol and Manchester, respectively, with an overall rate of 0.9%. The confirmed positive rate was 0.73, 0.53 and 0.65% for the three centres with an overall rate of 0.63%. Donors with an ALT > 45 IU/l, or with confirmed anti-HBc, were interviewed with a medical questionnaire for risk factors. The major contributing factors in donors with a raised ALT were alcohol consumption and obesity.

Recommendations for the investigation of abnormal hepatic function in asymptomatic workers

Occupational medicine programs use medical surveillance tests to measure physiologic parameters that may be affected by workplace exposures. Surveillance tests can detect early detrimental changes before workers manifest recognizable symptoms. Hepatic function testing is one type of surveillance test used to monitor workers exposed to hepatotoxins. However, a significant proportion of these test reports return showing abnormal hepatic function without a readily apparent etiology. Follow-up investigation of abnormal liver enzyme tests is a commonly encountered problem in occupational medicine clinics. The algorithm proposed in this paper will outline a systematic approach for investigating abnormal hepatic function tests from asymptomatic workers.

[Markers of viral hepatitis B and D and levels of alanine aminotransferase in military blood donors: a profile of 30,000 blood donations in 1989]

Serologic data for B and D viral hepatitis are studied on 30,000 military blood donors. Because of legal norms of blood products for transfusion 761 donations (2.53% have been destroyed). Exclusion criteria for viral B hepatitis and ALT are independent. In this study the prevalency of HBV infections is significantly lower than for other blood centers: probably in account of the young age of military blood donors.

Effect of body mass and other factors on serum liver enzyme levels in men attending for well population screening

Alcohol abuse is usually regarded as the most likely cause of elevated serum liver enzyme values in those attending for well population screening, but we have found increased body weight to be an important contributing factor. We have measured serum levels of alanine amino-transferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) in approximately 21,000 men attending for routine health screening, and related these to behavioural factors such as alcohol consumption, cigarette smoking, exercise level and obesity. The levels of all three enzymes were positively correlated with levels of alcohol consumption. Decreasing levels of physical activity were associated with increases in mean ALT and GGT levels. Cigarette smoking showed only a weak effect on ALT and AST, which became non-significant after multivariate statistical analysis, but increasing consumption of cigarettes was associated with increased mean levels of GGT. In contrast, all three enzymes showed marked increases in mean levels with increasing body mass index (BMI). The effect of obesity was particularly important in the case of ALT: the prevalence of increased ALT values in obese subjects (BMI greater than or equal to 31 kg/m2) was more than eight times that in those with normal weight (BMI less than or equal to 25 kg/m2), even after allowing for the confounding effect of alcohol consumption. This study is concerned solely with male subjects, but we hope to extend the analysis to females in the near future.

[Significance of alanine aminotransferase and reduction of post-transfusion non-A, non-B hepatitis]

To appreciate the test based on the activity of sera alanine aminotransferase (ALT) in the reduction of non-A non-B post-transfusional hepatitis, a study of the variation of this enzyme's activity was done versus several parameters: sex, age and acquired diseases. The population which included 25,813 Parisian blood donors (41.2% of men and 58.8% of women) was divided into two groups: the first was constituted of 25,585 subjects (40.9% of men and 59.1% of women) without clinical etiology and biological diseases, it will be the reference population; the second group was composed of 173 subjects (68.2% of men and 31.8% of women) who had acquired biological markers or clinical diseases during the life. The study within the reference population showed a sexual dimorphism. The study by dispersion diagrams in the population with high seric activity of ALT could explain the causes of blood donors' elimination.

Persistent alanine aminotransferase elevation in healthy Swedish blood donors--mainly caused by obesity

Five hundred consecutive healthy blood donors were tested for serum alanine aminotransferase (ALT) and 44 (8.8%) had increased levels. Donors with and without raised ALT were compared in several aspects but only weight (expressed as percentage of ideal body weight) and sex differed significantly (119.1 +/- 14.5 and 106.3 +/- 12.8%, respectively; p less than 0.001 and males 97.7 and 77.1%, respectively; p less than 0.01). The 44 donors with raised ALT were followed up and in 13 out of 15 donors with persistently raised ALT without obvious reason, a liver biopsy was performed. Ten donors had various degrees of liver steatosis, 2 had normal liver morphology and in 1 donor chronic hepatitis could not be ruled out. If ALT screening is introduced as a surrogate test for non-A, non-B hepatitis in Swedish blood donors, we suggest that a correction for overweight must be considered in order to minimize donor loss.

Diseases transmitted by blood transfusion

Except for post-transfusion hepatitis (PTH), the transmission of disease by blood transfusion appears to be very limited. There are only a few case reports documenting the transmission of malaria and other parasitic diseases, syphilis, or bacterial infections. The ability to eradicate PTH will depend on the development of sensitive-specific tests for the non-A, non-B agent(s). In the interim, two important steps that might be taken to reduce the incidence of PTH are the careful recruitment of blood donors and, most important, the judicious use of blood and its components.