Typically, low alanine aminotransferase (ALT) levels in the blood are considered normal, and it is high levels of ALT that should be cause for concern, according to Lab Tests Online. High ALT levels can be indicative of liver damage caused by hepatitis or cirrhosis, lead poisoning, exposure to carbon tetrachloride, necrosis (large tumor decay), mononucleosis and some medicinal use, including statins, antibiotics, chemotherapy, aspirin, narcotics or barbiturates, according to WebMD. Growth spurts in children can also lead to increase ALT levels.
What is considered normal ALT levels can differ depending on laboratory where the test is performed and the health condition of the patient. However, according to WebMD, the normal range for men is usually 10 to 40 units per liter and the normal range for women is usually 7 to 35 unites per liter.
Since numerous factors can heavily affect the results of the ALT testing, thereby rendering the results inaccurate or unhelpful in diagnosing health issues, it is important for a patient to discuss with his or her doctor if he or she takes any medications or medicinal herbs, has any allergies to medications or might be pregnant. The test is performed by taking a sample of blood.