A High Liver Enzyme Result Does Not Trigger a Second-Stage Health Exam - AST, ALT and GGT Reference Ranges and What Comes Next

The second-stage exam is not triggered by any abnormal finding

The national general health examination is built so that the first stage screens a set of items, and only certain suspected conditions move to a second stage. That list is fixed: suspected hypertension, diabetes, dyslipidaemia, pulmonary tuberculosis, depression (or early psychosis) and hepatitis C. Of those, hypertension, diabetes and tuberculosis proceed to confirmatory testing at a clinic or hospital.

Liver enzymes are not on the list. Even where AST and ALT exceed the reference range and the report reads "suspected liver disease", the NHIS does not attach a free follow-up test. The report simply advises seeing a doctor, and that is the end of it. An ultrasound or a hepatitis panel after that is ordinary outpatient care, with the usual patient share of the cost. The difference between report lines that lead somewhere and lines that do not becomes obvious when set against the fasting glucose band of 100–125.

Reference ranges — the three numbers say different things

The reference ranges published by the Korea Disease Control and Prevention Agency's national health information portal are as follows.

Test	Reference range	What it mainly reflects
AST	0–40 IU/L	Liver cell injury — but also present in muscle and heart
ALT	0–40 IU/L	Liver cell injury; more specific to the liver
GGT	Men 11–63 / women 8–35 IU/L	Biliary system, alcohol, medication
Total bilirubin	0.2–1.2 mg/dL	Bile excretion, haemolysis
Albumin	3.3–5.2 g/dL	The liver's synthetic capacity
ALP	Adults 30–115 IU/L	Biliary system, bone

One point is easy to miss. AST and ALT are not a single "liver number". AST also sits in muscle and heart tissue, so it rises after a punishing workout a few days before the test, or after severe muscle soreness. ALT is weighted towards the liver and reflects hepatocyte injury more accurately. A raised AST on its own therefore reads differently from a raised AST alongside a raised ALT.

GGT belongs to a different system altogether. It responds sensitively to biliary problems and to alcohol and medication. If AST and ALT are normal while GGT alone is high, the first questions go somewhere other than hepatocyte injury. Conversely, a normal GGT with raised AST and ALT points the search away from alcohol first.

Common reasons the numbers move

A result slightly above the reference range does not amount to liver disease. In practice, conditions on the day of the test move these figures often.

• Hard exercise shortly before the test — AST released from muscle is measured along with the rest
• Alcohol — GGT usually responds first
• Fatty liver — worth reading alongside weight and waist measurement
• Medication and supplements — analgesics, anticonvulsants and some supplements have an effect
• Viral hepatitis — hepatitis B and C status is established by separate testing

If you take several supplements together, this is worth auditing. Overlapping ingredients across products are extremely common. How to work out what you are actually taking is set out in reading a supplement label.

Whether it repeats matters more than a single value

What clinicians look at first is not the absolute figure but whether it repeats in the same direction. A value slightly raised once and normal at the next test means something different from the same value holding across two or three check-ups.

So the most practical preparation on receiving a report is to put it beside your previous ones. Past results are available through the National Health Insurance Service website and app under health examination results. Thirty-eight two years ago, 41 last year and 55 this year is a different story. At the consultation, "it has risen like this over three years" is far more useful than "it is 55 this year".

What to bring to the appointment

If you decide to see a doctor, assembling the following makes the consultation shorter and more accurate.

• The original report, including earlier rounds
• Alcohol intake over the past three months — as numbers: how many times a week, how many drinks each time
• Every medication and supplement you take — photographs of the packaging are fine
• Weight change — up or down over the past year
• Whether you have ever been tested for hepatitis B or C, and the result

Which further tests to run, and which causes to exclude first, is for the treating doctor to decide. Searching a number online and reaching your own conclusion is particularly risky with this panel, because the range of possible causes is wide and some of them become hard to reverse with time.

Not missing the check-up is the prior step

Tracking over time only works if the check-ups happen. The general health examination is provided once every two years (annually for non-office workers), and eligibility can be confirmed through NHIS notices and the The Health Insurance app. Let the eligible year pass and there is simply no data for that round. Eligibility and what happens when a check-up is missed are covered in who pays the fine for a missed national health check-up.

If you are putting off care because of the cost, it is worth checking whether part of what you have already paid can come back. The out-of-pocket ceiling and health insurance refunds is the channel for that.

What to do on the day the report arrives

• ① Read AST, ALT and GGT separately. They do not say the same thing
• ② Pull out the previous rounds and look at the trend
• ③ Note exercise, alcohol and medication before the test — the things that could have moved it
• ④ No second-stage exam is coming — book the appointment yourself
• ⑤ Bring the report, drinking volume, medication list and weight change as numbers

Compiled as of August 2026 from the liver function test reference ranges published by the Korea Disease Control and Prevention Agency's national health information portal and from the National Health Insurance Service's general health examination guidance (second-stage examination limited to those with suspected hypertension, diabetes, dyslipidaemia, pulmonary tuberculosis, depression or hepatitis C). Reference ranges vary slightly by laboratory and assay method. This article is general information to help you read a test result and does not replace diagnosis or treatment. If a value falls outside the reference range, take the report to a medical institution and be seen.