Several drugs elevates the ALT levels.

None of the placebo-treated patients had maximum ALT levels of more than three times the upper limit of normal, while 31% to 44% of the subjects in the four acetaminophen groups did.

Most increases in ALT levels are caused by liver damage.

But when the liver is damaged or diseased, it releases ALT into the bloodstream, which makes ALT levels go up.

Alcoholic liver damage may see fairly normal ALT levels, with AST 10x higher than ALT.

Fluctuation of ALT levels is normal over the course of the day, and ALT levels can also increase in response to strenuous physical exercise.

When elevated ALT levels are found in the blood, the possible underlying causes can be further narrowed down by measuring other enzymes.

For example, elevated ALT levels due to liver-cell damage can be distinguished from biliary duct problems by measuring alkaline phosphatase.

Also, myopathy-related ALT levels can be ruled out by measuring creatine kinase enzymes.

Many drugs may elevate ALT levels, including Zileuton, omega-3-acid ethyl esters (Lovaza), anti-inflammatory drugs, antibiotics, cholesterol medications, some antipscyhotics such as Risperidone, and anti-convulsants.