Elevated liver enzymes: how to read ALT, AST and GGT

Liver enzymes such as ALT, AST and GGT leak into the blood when liver cells are irritated or bile flow is affected. Mild rises, up to about two to three times the upper limit, are very common and are most often linked to fatty liver, alcohol or medicines. They are often temporary. What matters is how high, which enzymes, and whether they stay raised on a repeat test.

Updated: 2026-10-26

Reference ranges

Category	Reference range
ALT (SGPT)	up to about 35–45 U/L (IU/L)
AST (SGOT)	up to about 35–40 U/L (IU/L)
GGT, men	up to about 55–60 U/L (IU/L)
GGT, women	up to about 35–40 U/L (IU/L)
ALP	about 30–130 U/L (IU/L)

Upper limits differ quite a lot between labs and by sex; use the range on your report.

What each liver enzyme tells you

ALT (alanine aminotransferase): found mainly in liver cells; the most liver-specific of the group.
AST (aspartate aminotransferase): in the liver but also in muscle and the heart, so it can rise after hard exercise or muscle injury.
GGT (gamma-glutamyl transferase): sensitive to alcohol and some medicines, and rises with bile flow problems.
ALP (alkaline phosphatase): from the bile ducts and from bone; naturally higher in growing teenagers and in pregnancy.
Bilirubin and albumin, also part of the LFT panel, reflect how well the liver processes and makes substances.

Elevated liver enzymes causes

Fatty liver, now often called metabolic dysfunction-associated steatotic liver disease (MASLD): the most common cause in the UK and US, linked to weight, type 2 diabetes and high triglycerides.
Alcohol, which particularly raises GGT and AST.
Medicines and supplements: some painkillers, antibiotics, cholesterol-lowering medicines, and herbal or bodybuilding products. Do not stop prescribed medicine without advice.
Viral hepatitis (hepatitis B, C, sometimes A or E) and glandular fever.
Strenuous exercise in the previous days, especially weight training, which raises AST and ALT from muscle.
Less common causes: autoimmune hepatitis, haemochromatosis (iron overload), coeliac disease, thyroid problems, Wilson's disease.

ALT of 60 or high ALT and AST: what it means

An ALT of 60 U/L is about one and a half times a typical upper limit. With no symptoms, this is a mild rise that is usually repeated in one to three months and looked at alongside weight, alcohol intake, medicines and other blood tests. Values more than about ten times the limit, in the hundreds or thousands, point to acute liver injury and are dealt with urgently.

The pattern also helps. When AST is more than twice ALT, alcohol is one of the main suspects. When ALT is higher than AST, fatty liver and viral hepatitis are more common. A raised ALP and GGT with near-normal ALT suggests the bile ducts rather than liver cells.

GGT high, everything else normal

An isolated raised GGT is a frequent finding. The usual explanations are alcohol (even at moderate intake), fatty liver, and certain medicines such as some anti-epileptics. It may settle within a few weeks of cutting down alcohol. Your doctor may repeat it with an ultrasound if it stays high, or if other enzymes start to rise.

When to see a doctor

Mildly raised liver enzymes should be discussed with your GP or doctor, who in the UK may order a "liver screen" and a scan. Seek urgent care (NHS 111, urgent care, A&E or the emergency room) if you have abnormal liver tests and:

yellow skin or eyes, dark urine or pale stools;
confusion, unusual sleepiness, vomiting blood or black stools;
severe pain in the upper right abdomen, especially with fever;
you have taken more than the recommended dose of any over-the-counter painkiller, even if you feel well: liver damage can appear a day or two later;
ALT or AST above about ten times the upper limit, or a call from the lab.

Sources

Written using public information from:

British Society of Gastroenterology: Guidelines on the management of abnormal liver blood tests
NICE (National Institute for Health and Care Excellence): Non-alcoholic fatty liver disease (NG49)
American College of Gastroenterology: Evaluation of abnormal liver chemistries
British Liver Trust
MedlinePlus (US National Library of Medicine): Liver function tests

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Frequently asked questions

What causes elevated liver enzymes?

Most commonly fatty liver, alcohol and medicines or supplements. Viral hepatitis, hard exercise and less common liver conditions are other causes. The pattern of enzymes helps point to which one.

Is ALT 60 dangerous?

Usually not. It is a mild rise that is generally rechecked and investigated calmly. Much higher values, or rises with symptoms such as jaundice, need faster attention.

Can exercise raise liver enzymes?

Yes. Strenuous exercise, especially weightlifting, can raise AST and ALT for several days because they also come from muscle. Avoid heavy workouts before a repeat test.

Can elevated liver enzymes return to normal?

Often, yes, especially when the cause is alcohol, a medicine or fatty liver and that factor is addressed with your doctor's guidance.

Do I need to stop drinking alcohol if my liver enzymes are high?

Cutting down or stopping alcohol before a repeat test is often advised, because it makes the result easier to interpret and GGT and AST can fall within weeks. Your doctor will give advice that fits your situation.

This material is for general information only. It is not a medical opinion and does not replace a consultation with a doctor. Reference ranges depend on the laboratory and the method — rely on the range printed on your own report. Your doctor makes the final interpretation.