Information on Liver AST and ALT Levels

Submitted by Medical Health Test Team on October 16, 2012

The existence of some specific liver enzymes in your blood can help determine the amount of damage to your liver. Normally, these enzymes exist within the liver. However if the liver is damaged or injured these enzymes are thrown out into the blood stream. Enzymes help speed up the routine chemical reactions in the body. Aminotransferases are the most widely used liver enzymes. This enzyme includes alanine aminotransferase (ALT or SGPT) and aspartate aminotransferase (AST or SGOT). These enzymes therefore are normally present in the liver, but when liver is damaged, these enzymes are spilled into the blood signaling liver damage. The liver uses these enzymes to metabolize amino acids and make protein.

The normal range of values for AST (SGOT) is from 5 to 40 units per liter of serum (the liquid part of the blood). The normal range of values for ALT (SGPT) is from 7 to 56 units per liter of serum. AST and ALT signal damage or disease in the liver, but higher than normal levels of these enzymes do not always indicate liver disease.

Elevated levels of these enzymes could also be due to muscle damage. Sometimes, patients with acute viral hepatitis A may develop very high levels of AST and ALT in the blood. But most of the times, these patients recover without residual liver disease. Some patients with chronic hepatitis C may show slightly elevated levels of AST and ALT. There may be chances that some of the patients may have developed chronic liver disease such as chronic hepatitis or cirrhosis. Thus, it proves that level of these enzymes in blood does not give any indication on functioning of the liver.

The highest levels of AST and ALT are found with disorders that can kill many liver cells. This occurs in conditions such as acute viral hepatitis A or B, overdose of acetaminophen, and prolonged dysfunctioning of the circulatory system where the liver is deprived of fresh oxygen and blood. n these cases AST and ALT serum levels could range anywhere from ten times the upper limit to thousands of units per liter. Normal mild to medium elevation of liver enzymes is common. The most common cause for this may be fatty liver. The major causes of fatty liver are obesity, diabetes, and over consumption of alcohol.

It is better to test the level of AST and ALT in blood regularly to check if it is increasing, decreasing, or remaining stable. It is always better to consult a physician immediately if you notice any abnormal rise and fall in these enzyme levels.

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