Liver enzyme limits by sex differ: 33 U/L tops the ACG's healthy ALT range for men, 25 for women. So why might your lab print a higher number?

Rhabdomyolysis raises AST because muscle holds the enzyme too, yet dark urine or severe muscle pain, not the lab number, is what sends you to the ER.

An AST/ALT ratio below 1 says little alone: in a 515-patient fatty liver biopsy study, advanced scarring was similarly common with normal enzymes.

FIB-4 calculator math is simple, yet in one US study 10% of low-risk results were not low risk on stiffness testing. See what that means.

FIB-4 above 1.3 flags a second test, not a diagnosis. Over 65 the cutoff is 2.0, and age alone can lift the score

An AST/ALT ratio above 2 points to advanced liver injury more than drinking: 64% of 313 people in alcohol withdrawal had a ratio of 1.0 or less.

High AST with normal ALT often points beyond the liver. See how ACG guidance sorts muscle, heart and hemolysis causes by test.

High AST levels that are only mildly raised are common, per Mayo Clinic. Know which symptoms mean you should not wait to retest.

The AST normal range on your report may differ from what you read online: about 1 in 20 healthy people fall outside it.

AST blood test results can come from liver, muscle or heart, so one number cannot show where the rise began. Here is how to read yours.