Many things can cause an elevated in the liver enzymes. You note that alcohol and hepatitis should not be causes. Anatomical abnormalities in the liver and gallbladder, as well as fatty liver, can also cause an elevation. Of course, medications like Tylenol affects the liver as well, but typically less than 4 grams of Tylenol per day is acceptable. More uncommon causes can be things like autoimmune hepatitis as well as hemochromatosis.
The appropriate next test would be a liver ultrasound - which can evaluate the liver and gallbladder anatomy. Typically a liver biopsy is not considered unless the ALT is 3 times greater than normal (i.e. more than 100).
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Thanks,
Kevin, M.D.