Alanine transaminase

(ALT); transaminase enzyme (EC 2.6.1.2), Syn alanine aminotransferase (ALAT), serum glutamic pyruvic transaminase (SGPT)

Description
ALT catalyzes the alanine cycle and is present in blood serum, different tissues and the liver. ALT levels change in the circadian rhythm and upon phycisal exercise. Elevated serum ALT levels outside the normal range are indicative of medical problems such as viral hepatitis or liver damage, thus making ALT measurements useful in screening for liver problems, or congestive heart failure and myopathies. Owing to its physiological variation and its association with different medical conditions, ALT measurement is usually supplemented with other analyses to confirm a medical condition and to give a more specific diagnosis.

Relevance to Hemoglobinopathies
Until the introduction of reliable immuno-based tests for Hepatitis C, blood from donors with elevated ALT levels was rejected by international branches of the Red Cross, in order to err on the side of safety and exclude potentially infected blood supplies. Many donors formerly rejected under this policy would now be eligible to donate blood.