You got your blood test back and something is flagged H next to ALT or AST. Your doctor mentioned liver enzymes, and now your mind is racing about what could be wrong.
Take a breath. Here is what it actually means — in plain English — so you can understand the numbers instead of fearing them.
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What are liver enzymes?
Liver enzymes are proteins that get released into your blood when liver cells are damaged or inflamed. Your blood test measures how much of each is circulating, so a higher-than-usual level suggests your liver cells are leaking more than normal.
The important thing to remember is that elevated enzymes are a signal, not a diagnosis. They tell your provider to look closer — they do not, on their own, name the cause.
The four main liver enzymes
ALT (Alanine Aminotransferase)
Normal 7–56 units/L
The most specific marker of liver health. ALT is raised by alcohol, fatty liver, hepatitis and medications like statins or Tylenol.
AST (Aspartate Aminotransferase)
Normal 10–40 units/L
Found in the liver but also in your muscles and heart. AST is raised by the same causes as ALT plus heart attack, muscle injury and intense exercise.
ALP (Alkaline Phosphatase)
Normal 44–147 units/L
Comes from the liver and from your bones. ALP is raised by liver disease, bone disorders and pregnancy — the last one being a normal elevation.
GGT (Gamma-Glutamyl Transferase)
Normal 8–61 units/L
The enzyme most sensitive to alcohol use. GGT is often checked alongside ALP to help pinpoint where an elevation is coming from.
How high is too high?
Mild (1–3x normal)
Often temporary — a medication, a recent illness or a few drinks can nudge enzymes up. Frequently rechecked rather than treated right away.
Moderate (3–10x normal)
Warrants investigation. Your provider will usually look for a cause and may order further tests or imaging.
Severe (10x+ normal)
Urgent medical attention needed. This level can signal significant liver injury and should be evaluated promptly.
Common causes of elevated liver enzymes
Fatty liver disease
The most common cause of mildly elevated enzymes, often tied to weight, diet and metabolic health.
Alcohol consumption
A frequent driver of raised enzymes, especially GGT and AST.
Medications
Statins, Tylenol (acetaminophen) and some antibiotics can all push enzymes up.
Hepatitis A, B or C
Viral infection of the liver can cause significant enzyme elevation.
Thyroid problems
An out-of-balance thyroid can show up as abnormal liver enzymes.
Intense exercise
Hard workouts can raise AST specifically, since it also comes from muscle.
Red flags — when to call your doctor
Most mildly elevated enzymes are not emergencies. A few signs are worth a prompt call to your provider — especially if you also feel unwell. Reach out about:
AST or ALT above 10x the normal range
Yellowing of the skin or eyes (jaundice)
Dark urine or pale stools
Severe abdominal pain
Elevated liver enzymes combined with elevated bilirubin
If you have severe symptoms such as chest pain, trouble breathing, fainting or confusion do not wait for a callback — call 911 or go to the nearest emergency room.
Questions to ask your doctor
1How high are my ALT and AST, and how many times above normal is that?
2Could a medication, alcohol or recent exercise have caused this elevation?
3Do I need further testing like an ultrasound or a hepatitis screen?
4Should I stop or change any of my current medications?
5When should I repeat my liver panel to see if the numbers are improving?
6Are there warning signs like jaundice or dark urine I should watch for before then?
Still worried about your liver enzymes?
Upload your blood test to Nuvela AI for a clear plain-English breakdown — free.
Medical disclaimer: This page is educational and is not medical advice, diagnosis or treatment. Lab results must be interpreted by a licensed healthcare provider who knows your full history. Always follow your provider’s guidance and call 911 in an emergency.