ALT and AST are mainly found in the liver within the hepatocytes. They reflect the state of liver function in the body and are elevated when liver cells become necrotic. The degree of elevation corresponds to the degree of liver cell damage and is therefore the most commonly used indicator of liver function today.
The distribution of these two enzymes within the liver cells is different, with ALT mainly in the hepatocyte plasma and AST mainly in the hepatocyte plasma and mitochondria of the liver cells. Therefore, the degree of elevation of ALT and AST and their ALT/AST ratios vary between different types of hepatitis.
In acute hepatitis and in mild forms of chronic hepatitis, the mitochondria of the hepatocytes remain intact despite the damage to the liver cells. Therefore, the only ALT that is released into the blood is that which is present in the plasma of the hepatocytes, so the main manifestation is an increase in ALT and the ALT/AST ratio is >1 or even >2.
However, in severe hepatitis liver failure, due to massive hepatocyte necrosis, the number of normal hepatocytes is low and the production and release of transaminases is low, while serum bilirubin is significantly elevated.
The level of aminotransferases is a very important test for patients with hepatitis. In general, transaminases should fall to normal within 4-6 weeks of the onset of acute hepatitis. In relapses of hepatitis, elevated transaminases may precede symptoms. If the transaminases remain mildly abnormal for more than 3 months, the disease is likely to become chronic. A large increase in transaminases in a patient with cirrhosis is a sign that the disease may be developing into an active form and warns of this.
However, when the disease has progressed to a certain severity, there is massive necrosis of liver cells and the liver loses its ability to produce aminotransferases. In this case, the transaminases in the blood are reduced but the jaundice continues to rise, a phenomenon known as "enzyme-biliary separation", which often indicates a deteriorating condition.
In conclusion, an increase in transaminases generally reflects the degree of liver cell damage, but the level of the enzyme does not fully indicate the severity of the disease or its prognosis. Therefore, it is important to analyse the symptoms, signs, pathology and other clinical findings to determine whether the disease is improving or deteriorating, rather than relying solely on minor fluctuations in enzyme values.
In addition, in severe hepatitis, due to massive hepatocellular necrosis, the ALT in the blood gradually decreases, while the bilirubin progressively increases, i.e. the phenomenon of "bile enzyme separation", which is often a precursor to hepatic necrosis. In the recovery phase of acute hepatitis, if ALT is normal but γ-GT remains elevated, this is often indicative of chronic hepatitis. In chronic hepatitis, a persistent elevation of γ-GT above normal reference values indicates active chronic hepatitis.
The Seamaty
Portable Biochemistry analyser is flexible in its use, with results available in 12 minutes from the time the sample is released to the time the report is read, enabling rapid testing and shortening the waiting time for patients and providing clinicians with biochemical references as soon as possible.
