Alanine transaminase (ALT) is a transaminase enzyme.
It was formerly called serum glutamate-pyruvate transaminase or serum glutamic-pyruvic transaminase (SGPT).
ALT is found in plasma and in various body tissues but is most common in the liver.
Serum ALT level, serum AST (aspartate transaminase) level, and their ratio (AST/ALT ratio) are commonly measured clinically as biomarkers for liver health.
ALT enzyme catalyzes the transfer of an amino group from L-alanine to α-ketoglutarate.
The products that result from this reversible transamination reaction are pyruvate and L-glutamate (L-alanine + α-ketoglutarate ⇌ pyruvate + L-glutamate).
ALT requires the coenzyme pyridoxal phosphate.
It is commonly measured as part of liver function tests.
It is a component of the AST/ALT ratio.
Reference range values for patients, 0-40 IU/L.
Typical reference intervals for ALT are:
Female ≤ 34 IU/L
Male ≤ 45 IU/L
Significantly elevated levels of ALT: viral hepatitis, diabetes, congestive heart failure, liver damage, bile duct problems, infectious mononucleosis, or myopathy.
Commonly used as a way of screening for liver problems.
Elevated levels may be caused by dietary choline deficiency.
Elevated levels of ALT do not automatically mean that medical problems exist.
Levels normally fluctuate over the course of the day.
ALT levels can also increase in response to strenuous physical exercise.
Elevated ALT levels due to hepatocyte damage can be distinguished from bile duct problems by measuring alkaline phosphatase.
Myopathy-related elevations in ALT should be suspected when the aspartate transaminase (AST) is greater than ALT.
Many drugs may elevate ALT levels: omega-3 acid ethyl esters, anti-inflammatory drugs, antibiotics, cholesterol medications, some antipsychotics, anticonvulsants, and
acetaminophen.