When the check-up results arrive, most people read only the verdict on page one — "normal A / normal B / suspected condition" — and file it away. Yet the numbers inside flag trouble long before symptoms appear.
That matters most for the liver and kidneys, the "silent organs." They don't hurt until damage is well advanced. So these two are checked with numbers, not symptoms.
Korea's national health check-up includes liver function (AST, ALT, γ-GTP), kidney function (serum creatinine, eGFR, urine protein), fasting glucose, hemoglobin and cholesterol. The answers are already in the report you've been handed.
Liver numbers — AST, ALT, γ-GTP
AST and ALT are enzymes inside liver cells. When those cells are damaged, the enzymes leak into the blood and the values rise. In other words, a rise means liver cells are being injured.
- ALT is relatively liver-specific, so an isolated rise points first to fatty liver or hepatitis.
- γ-GTP responds sensitively to alcohol and bile-duct problems, and falls fairly quickly when you cut back.
- Fatty liver can exist with normal values — it's often found on ultrasound instead.
Note: AST is also present in muscle, so hard exercise before the test can raise it temporarily. The trend across repeat tests matters more than one reading.
Kidney numbers — creatinine, eGFR, urine protein
- Serum creatinine — a waste product from muscle use that the kidneys filter out. When function drops, it accumulates in the blood and rises. (High muscle mass can raise it even with normal kidneys.)
- eGFR — an estimate of how much blood the kidneys filter per minute, adjusted for age and sex. Broadly, 90 or above is good, while below 60 persisting three months or more raises suspicion of chronic kidney disease.
- Urine protein — checks whether protein is leaking into urine; healthy results are usually negative. A positive can signal a filtering problem and warrants repeat and detailed testing. (Intense exercise or fever can cause a temporary positive.)
The "late" signs your body shows
These symptoms tend to appear once things have already progressed — another reason to check the numbers first.
- Kidneys — foamy urine that doesn't settle, swelling around the eyes and ankles, frequent night urination, unexplained fatigue or itching
- Liver — heavy fatigue, poor appetite, discomfort under the right ribs, yellowing of the eyes or skin (jaundice), darker urine
If your numbers are borderline high
- Cut alcohol — the most direct lever on γ-GTP and liver values.
- Lose 5–10% of body weight — the most effective step for fatty liver.
- Manage blood pressure and glucose — hypertension and diabetes are the two leading causes of chronic kidney disease. (See also the prediabetes signs guide.)
- Be careful with painkillers and supplements — they can burden the liver and kidneys. Tell your doctor what you take.
- Repeat the test — don't judge on a single value; recheck when your doctor advises.
FAQ
Is "normal B" fine?
It means no suspected disease, but you're in a borderline zone needing lifestyle change. Ignored, it often becomes "suspected condition" at the next check.
My liver values are slightly high but I feel nothing.
The liver typically causes no symptoms until damage is significant. Treat feeling fine as expected, and focus on finding the cause (fatty liver, alcohol, medication, hepatitis).
Does a low eGFR mean dialysis?
No. Early on, the goal is slowing progression through blood-pressure and glucose control and lifestyle. Earlier detection means more room to manage.
How should I prepare for the test?
Generally fast for 8+ hours and avoid heavy drinking or intense exercise the day before, which can distort values.
By the time the liver and kidneys hurt, it's late. The numbers in that filed-away report speak long before symptoms do.
This is general health information and does not replace medical diagnosis or treatment. Reference ranges vary by laboratory and individual — always review results with a healthcare professional.
