Serum ALT activity

Swaim, L. D., H. W. Taylor, and G. C. Jersey. 1985. The effect of handling techniques on serum ALT activity in mice. Journal of Applied Toxicology 5 160-162. 

Serum ALT activity is the primary method to assess ALI associated with drugs. Despite not formally qualified against human histology for DILI, ALT has been widely regarded. Several limitations have been associated with ALT activity (Senior, 2012 Antoine et al., 2013b). 

Liver dysfunction. In a 4-year study in 1221 liver dysfunction-free (serum aspartate aminotransferase [AST] and alanine aminotransferase [ALT] <39 lU/L and no medical care for or no past history of liver disease) males aged 35-56 years, was investigated for the association of coffee consumption with the development of increased serum AST and/or ALT activities. From the analysis using the Kaplan-Meier method, the estimated incidence of serum AST and/ or ALT > 40 lU/L, > 50 lU/L, and > 60 lU/ L decreased with an increase in coffee consumption. From the Cox proportional haz-... 

Within a few minutes of an infant s birth, fluid passes from the blood vessels into the extravascular spaces. This fluid is similar to plasma except that the fluid lost from the intravascular space contains no protein. Consequently the plasma protein concentration increases. The serum activities of several eu2ymes, including CK, GGT, and AST, are high at birth, but the increase of alanine aminotransferase (ALT) activity is less than that of other enzymes. 

Liver disease is the most important cause of increased transaminase activity in serum. In most types of liver disease, ALT activity is higher than that of AST exceptions may be seen in alcoholic hepatitis, hepatic cirrhosis, and liver neoplasia. In viral hepatitis and other forms of liver disease associated with acute hepatic necrosis, serum AST and ALT... 

Although serum activities of both AST and ALT become elevated whenever disease processes affect liver cell integrity, ALT is the more liver-specific enzyme. Serum elevations of ALT activity are rarely observed in conditions other than parenchymal liver disease. Moreover, elevations of ALT activity persist longer than do those of AST activity. 

AST activity in serum is stable for up to 48 hours at 4"C. Specimens have to be stored frozen if they are to be kept longer. ALT activity should be assayed on the day of sample collection since activity is lost at room temperature, 4°C> and -25 °C. ALT stability is better maintained at -70 "C. Hemolyzed specimens should not be used. 

The large increase in the CK and LDH relative to the AST and ALT would indicate that muscle is the major tissue contributing to the increase in serum enzyme activities. However, muscle does not contain ALT which comes from the liver. AST and LDH are found in muscle, liver and erythrocytes. Thus, the tissues which could have contributed to the serum enzyme activities include muscle (either skeletal or cardiac), the liver or erythrocytes. 

Although most endpoints are amenable to a hormesis evaluation, some commonly assessed endpoints are inherently problematic. For example, serum enzyme activities such as those routinely taken to assess liver toxicity, such as ALT and AST, would not be a means to study hormesis because any changes from normal, whether high or low, may be indicative of some underlying pathology. In order to assess whether liver changes would be reflective of a hormetic response it may be necessary to utilize an animal model with a high predisposition to liver disease or to create experimental conditions that would promote the early onset of liver disease. 

AST were significantly below those seen in acute viral hepatitis. In addition, the ratio of the absolute values for serum ALT and AST often differ in the two diseases, tending to be greater than 1 in acute viral hepatitis and less than 1 in chronic alcohol-induced cirrhosis. The reason for the difference in ratio of enzyme activities released is not understood, but a lower level of ALT in the serum may be attributable to an alcohol-induced deficiency of pyridoxal phosphate. In addition, serologic tests for viral hepatitis were nonreactive. Her serum folate, vitamin B12, and iron levels were also slightly suppressed, indicating impaired nutritional status. 

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