There are a lot things this can be. You can have fatty infiltration of the
liver, HIV, hemochromotosis, Wilson's disease, some viral illnesses and
other things. I'd get the liver function tests repeated, as well as other
liver tests (like albumin, which the liver makes, and a lipid profile,
because the liver is involved in fat metabolism). If the values are out of
the normal range, I would  see a gastroenterologist for follow-up.

If you are overweight, go on a diet and get more exercise.

Jeff

If viral hepatitis testing was undertaken then I would assume that a
hepatic blood panel was also done which would include a repeat ALT.
Viral hepatitis usually is in the one to four times upper reference of
normal range for like Hepatitis C. IT is not unheard of to have 50-100X
upper limits of normal.

Most cases of chronic cell necrosis involves less than 7 times the
normal of tranaminases.
In this case it is almost X9 which is close to acute cell hepatic
necrosis. Acute cell necrosis usually involves a virus, toxin, alcohol
or ischemia. Chronic necrosis is usually associated with a low albumin
level and in chronic active hepatitis or cirrhosis with an elevated
globulin level. Autoimmune hepatitis and primary biliary cirrhosis
would also require additional testing such as an ANA, smooth muscle
antibody, and type I liver-kidney microsomal antibody. Some of the
other conditions were already mentioned such as Wilson's disease and
alpha one antitrypsin deficiency.

The alkaline phosphatase is important in further characterizing the
condition in terms of necrotic vs cholestatic. An ALK greater than 300
indicates cholestatic jaundice in which it appears you don't have or
and ALK less than 300 in  acute hepatocellular disease (viral, toxic,
chronic liver disease and infiltrative disease).

The transaminases are used more in diagnosis than as an indicator of
disease severity. The bilirubin and albumin are used more for that.

Apart from the conditions that Jeff mentioned is one important one that
would point to a false increase and that would be immunoglobulin
complexed ALT that is not cleared by the kidneys and so it is raised in
the blood. This is not a disease but a laboratory abnormality only.
Special techniques are needed to prove that but if the only abnormality
is an ALT then that would be highly suspicious. Pretty rare and I have
not seen one of those.

A liver biopsy might be undertaken if nothing shows up by non-invasive
testing.