Vol. 5, Issue 1 (2019)
Comparative study of transaminase ratio, AST, ALT and GGT in cases of chronic hepatitis
Author(s): Dr. Anil Batta
Abstract: The differential diagnosis between viral hepatitis and other liver diseases (particularly obstructive jaundice) is often difficult on purely clinical grounds. Damage to the liver causes changes in the pattern of the serum enzymes and this has led to the development in recent years of a number of enzyme tests. De Ritis described the ratio between the serum levels of aspartate transaminase (AST) and alanine transaminase (ALT) almost 50 years ago. While initially described as a characteristic of acute viral hepatitis where ALT was usually higher than AST, other authors have subsequently found it useful in alcoholic hepatitis, where AST is usually higher than ALT. These interpretations are far too simplistic however as acute viral hepatitis can have AST greater than ALT, and this can be a sign of fulminant disease, while alcoholic hepatitis can have ALT greater than AST when several days have elapsed since alcohol exposure. The ratio therefore represents the time course and aggressiveness of disease that would be predicted from the relatively short half-life of AST (18 h) compared to ALT (36 h). In chronic viral illnesses such as chronic viral hepatitis and chronic alcoholism as well as non-alcoholic fatty liver disease, an elevated AST/ALT ratio is predictive of long terms complications including fibrosis and cirrhosis It is characteristic of viral hepatitis that both levels are greatly increased, but the SGOT/SGPT ratio, normally greater than one, falls considerably below this figure. The AST/ALT ratio is the ratio between the concentrations of the enzymes aspartate transaminase (AST) and alanine transaminase, alanine aminotransferase (ALT) in the blood of a human or animal. It is measured with a blood test and is sometimes useful in medical diagnosis to differentiate between causes of liver damage, or hepatotoxicity. Most causes of liver cell injury are associated with a greater increase in ALT than AST; however, an AST to ALT ratio of 2:1 or greater is suggestive of alcoholic liver disease, particularly in the setting of an elevated gamma-glutamyl transferase. The AST to ALT ratio can also occasionally be elevated in a liver disease pattern in patients with nonalcoholic steatohepatitis, and it is frequently elevated in an alcoholic liver disease pattern in patients with hepatitis C who have developed cirrhosis. In addition, patients with Wilson's disease or cirrhosis due to viral hepatitis may have an AST that is greater than the ALT, though the ratio typically is not greater than two. When the AST is higher than ALT, a muscle source of these enzymes should be considered. For example, muscle inflammation due to dermatomyositis may cause AST>ALT. This is a good reminder that AST and ALT are not good measures of liver function when other sources may increase AST or ALT, because they do not reliably reflect the synthetic ability of the liver, and they may come from tissues other than liver (such as muscle) In a few cases of obstructive jaundice, the serum transaminase picture may initially resemble that in viral hepatitis, but the differential diagnosis can be established by repeating the determinations at intervals. Other enzyme tests, such as determination of alkaline phosphatase and 5’NT, may be used to confirm the biliary obstruction. The present study was undertaken in one hundred patients of hepatitis of sexes ranging 20 to 60 yrs. of age to compare serum levels or alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase & serum bilirubin. Forty of clinically healthy subjects were taken as control group. These were patient's attendants without any evidence of liver disease so as to equilibrate the socioeconomic status and age. The study group patients were either admitted to Rajindra Hospital & GMC, Patiala, or attending the OPD. A detailed clinical examination was carried out in all as per plan mentioned in materials & methods. Diagnosis of these patients was based on clinical findings.