Elevated liver enzymes (ALT/AST) on your bloodwork — what it means

You went in for a routine blood test — maybe an annual check-up, maybe before starting a new medication — and the report came back with a flag next to ALT or AST, marked high. If that has left you googling at midnight and worrying about your liver, take a breath. Mildly elevated liver enzymes are one of the most common abnormal results a GP sees, and the great majority are not an emergency. This article explains, calmly, what those enzymes actually are, what the usual causes are, what "how high" tends to mean, the sensible work-up your GP can order, and when the situation genuinely warrants a hepatologist. The goal is to replace anxiety with a plan.

What ALT and AST actually are

ALT (alanine aminotransferase) and AST (aspartate aminotransferase) are enzymes that live inside liver cells, where they do normal metabolic work. When liver cells are stressed, irritated, or injured, small amounts of these enzymes leak out into the bloodstream — so a raised level on a blood test is essentially a signal that some liver cells are under strain. That's the whole message the number carries: there is some liver cell irritation. What it does not tell you is the cause, how serious it is, or whether there is any permanent damage. Those questions are what the work-up is for.

One useful nuance: AST isn't unique to the liver — it's also present in muscle and red blood cells. So an isolated AST rise, especially after heavy exercise, a muscle injury, or in some muscle conditions, can come from outside the liver entirely. ALT is more liver-specific, which is why it's often the more informative of the two.

Two patterns: hepatocellular vs cholestatic

Liver blood tests aren't read one number at a time — the pattern across them is what points to the type of problem. Broadly there are two:

• Hepatocellular pattern (ALT/AST up): when the transaminases (ALT and AST) are the ones that are elevated, the process is one of liver cell injury or inflammation. This is the pattern of fatty liver, viral hepatitis, medication effects, and autoimmune liver disease.
• Cholestatic pattern (ALP/GGT/bilirubin up): when ALP (alkaline phosphatase), GGT (gamma-GT), and bilirubin are the ones that are elevated, the process points toward bile flow — a blockage or irritation of the bile ducts, such as gallstones or certain drug reactions.

Many results are mixed, and interpreting which pattern dominates is exactly the kind of judgement a specialist makes routinely. But knowing the framework helps you understand why your doctor is looking at the whole panel, not just the one flagged line.

The common causes — from most to least likely

When ALT/AST are up, most of the time the explanation comes from a fairly short list:

Fatty liver (NAFLD / MASLD) — the most common by far

Non-alcoholic fatty liver disease — now often called MASLD (metabolic dysfunction-associated steatotic liver disease) — is the single most frequent reason for mildly elevated liver enzymes in Canada. It's fat accumulating in the liver, closely linked to weight, insulin resistance, type 2 diabetes, and cholesterol. The good news is it's often reversible with weight and metabolic changes. Our companion guide on fatty liver disease in Canada covers what it is and what to do about it in detail.

Alcohol

Regular or heavy alcohol intake is a leading cause of raised enzymes. Classically, alcohol produces an AST that is higher than ALT (an AST:ALT ratio above 2 is suggestive), often with a raised GGT. Being honest with your doctor about intake genuinely changes the interpretation.

Medications and supplements

This one surprises people. Many prescription drugs can nudge liver enzymes up — but so can over-the-counter medicines (paracetamol/acetaminophen at high doses is the classic) and, importantly, herbal and "natural" supplements. Bodybuilding supplements, green tea extract, certain Ayurvedic and herbal preparations, and high-dose vitamins have all been linked to liver injury. Bring every bottle — prescription, OTC, and herbal — to your appointment.

Viral hepatitis B and C

Chronic hepatitis B and C can raise liver enzymes and are important to catch because they are treatable and, untreated, carry long-term risk. Both are diagnosed with simple blood serology. Hepatitis B is particularly relevant in some communities (more on that below); our detailed guide on hepatitis B in Canada covers testing and management.

The less common but important causes

When the usual suspects are ruled out, the work-up broadens to:

• Autoimmune hepatitis — the immune system attacking liver cells; treatable once identified.
• Haemochromatosis (iron overload) — a genetic tendency to absorb too much iron, screened with ferritin and iron studies. Worth knowing because it's manageable and heritable.
• Thyroid disease — both over- and under-active thyroid can disturb liver enzymes, which is why TSH is on the panel.
• Coeliac disease — can present with raised transaminases and is screened with a simple blood test.
• Muscle sources — remember AST also comes from muscle, so strenuous exercise, injury, or muscle disorders can raise it without any liver problem.

What "how high" suggests

The degree of elevation is a rough guide, not a diagnosis, but it helps set the tempo of the work-up:

• Mild elevation (up to roughly 2–3× the upper limit of normal): extremely common, most often fatty liver, alcohol, or medication. Usually investigated calmly over a few weeks rather than urgently.
• Moderate elevation: warrants a prompt, structured work-up to pin down the cause.
• Markedly elevated (very high, in the hundreds or thousands): this is a different situation — it can reflect acute hepatitis, a significant drug or toxin injury, or reduced blood flow to the liver, and it warrants prompt medical assessment, not watchful waiting.

Just as important as the number is the trend. A single flagged result is far less meaningful than a repeated one — which is why the first step is almost always simply to repeat the test.

The sensible work-up your GP can order

You don't need a specialist to start the investigation — your family doctor can order almost the entire work-up. Here is the reasonable panel:

• Repeat LFTs — confirm the abnormality is real and persistent, and reveal the pattern (hepatocellular vs cholestatic).
• Hepatitis B and C serology — simple, important, treatable-if-positive.
• Ferritin and iron studies — to screen for haemochromatosis.
• Metabolic markers — fasting glucose or HbA1c and a lipid panel, since fatty liver travels with metabolic syndrome.
• TSH — thyroid dysfunction can disturb liver enzymes.
• Coeliac serology — an easily missed cause.
• Liver ultrasound — looks directly at the liver for fat, texture, and structural issues.
• FIB-4 score — a simple calculation from your age, AST, ALT, and platelet count that estimates the risk of significant liver fibrosis (scarring). It's the single most useful tool for deciding who needs a specialist and who can be safely monitored.

The South Asian angle

If you're of South Asian background, two of the common causes on this list are more common in your community, which makes an abnormal liver enzyme result worth taking seriously — not fearfully, but seriously. First, fatty liver disease is highly prevalent among South Asians, tied to the same tendency toward insulin resistance and central weight gain that drives higher rates of type 2 diabetes at lower BMI. Second, hepatitis B prevalence is higher in populations from the Indian subcontinent and much of Asia, and it's frequently silent for years. Between these two, a large share of abnormal liver enzymes in South Asian patients trace back to fatty liver or hepatitis B — both of which are precisely the things a proper work-up is designed to find, and both manageable once identified.

When a hepatologist or GI referral is warranted

Most mildly raised enzymes are handled entirely by a GP. A specialist — a hepatologist or gastroenterologist — becomes appropriate when:

• The elevation is persistent despite addressing obvious causes, or markedly high.
• The FIB-4 score or ultrasound suggests significant fibrosis — scarring that needs specialist assessment and staging.
• The cause remains uncertain after the standard work-up, or autoimmune or genetic liver disease is suspected.
• There are features of chronic liver disease, or hepatitis B or C requiring treatment decisions.

The practical catch in Canada is that a gastroenterology or hepatology referral can mean a long wait — our overview of gastroenterologist wait times in BC lays out what to expect. That gap between finding an abnormal result and getting specialist eyes on it is exactly the space where an interim written opinion can help you understand your results and know what to push for.

How a specialist opinion from Ginie Health works

Here's the service in plain terms for exactly your situation — you have a flagged ALT or AST, your GP has ordered (or is about to order) some tests, and you'd like a specialist to make sense of the whole picture without waiting months. You upload your results — your LFTs, any hepatitis serology, ferritin, ultrasound report, and FIB-4 if you have it — and describe your history, medications, and supplements. Within 6 hours, for $45 CAD, you receive a written clinical opinion from a hepatologist or gastroenterologist trained at PGIMER Chandigarh or AIIMS — among the finest medical institutions in the subcontinent.

The written opinion tells you what your enzyme pattern actually means, which further tests to request, what your FIB-4 fibrosis risk looks like, and whether a formal hepatology or gastroenterology referral is warranted — so every conversation with your GP counts. It doesn't replace hands-on care; it makes the wait productive. If you'd rather talk it through, a live video consultation is available for $75 CAD. No referral required for either.