alt level extremely high in my cats blood test

[longhair]

Hello,
I am new to this forum and am looking for help.
my 12yr old cat Cecil has been noticeably sick for 4 days and when I took him to the vet for blood work, the first test the alt level did not register. So they tested again and test says his alt level is 2,438. The test says between 12-130 is normal and vet says its because of liver infection. Is it possible to have a level that high or is test wrong. Other levels on test are high but not extreme. Or so vet says.
Any information and help is greatly appreciated.
Thanks.