Also referred to as to Glutamate Pyruvate Transaminase (GPT)
Measurement of ALT activity is mainly performed to investigate liver disease. Increasingly ALT is being measured to monitor patients receiving antiretroviral drugs associated with hepatotoxicity such
as nevirapine (NVP) and stavudine (d47).
While both ALT and AST are raised with hepatocellular injury, ALT is more specific for detecting liver cell damage.
What are the Normal ranges for Serum ALT ?
5–35 IU/l
Causes of high levels of serum ALT
Liver disease
The most important cause of raised ALT activity is hepatocellular injury. With acute hepatocellular injury, AST levels are usually higher than ALT levels. As damage continues, ALT activity becomes higher. In viral hepatitis, both enzymes are usually raised before the patient becomes jaundiced.
In Liver cirrhosis:
ALT levels fall below AST levels. Both ALT and AST are raised in hepatitis caused by hepatotoxic antiretroviral drugs.
Obstructive liver disease is usually accompanied by only small or moderate ALT and AST rises especially in the early stages. With complete obstruction, enzyme levels fall.
ALT and AST enzymes are artefactually increased when haemolysis is present or if the blood has been stored without separation of the serum or
plasma.
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