Blood tests are a central part of health checkups in Korea.

A typical screening program may include tests for:

• Anemia and blood cell abnormalities
• Blood glucose and diabetes
• Cholesterol and cardiovascular risk
• Liver abnormalities
• Kidney function

Depending on the center and package, additional tests may include:

• HbA1c
• Uric acid
• Thyroid function
• Hepatitis B and C tests
• Iron and ferritin
• Vitamin D
• ESR or high-sensitivity CRP
• Tumor markers
• Other metabolic, hormonal, or nutritional tests

The exact panel varies between Korea’s national health screening program and private comprehensive health checkups.

More tests do not necessarily mean a better checkup. Some tests are useful for general screening, while others are more meaningful when selected according to age, sex, medical history, medication use, previous results, and individual risk.

This guide explains the blood tests commonly encountered in Korean health checkups and how to understand them.

Before Interpreting a Blood Test

A blood test should not be interpreted only by checking whether a result is marked “high” or “low.”

Results may be affected by:

• Recent meals
• Alcohol
• Exercise
• Dehydration
• Acute illness
• Pregnancy
• Medication
• Vitamins and supplements
• Smoking
• Temporary biological variation
• Differences between laboratory methods

A result slightly outside the reference range does not automatically indicate disease.

The significance of an abnormal result depends on:

• How abnormal it is
• Whether related tests are also abnormal
• Whether the abnormality is new or persistent
• Whether the value has changed over time
• Symptoms and medical history
• Medication and supplement use

Previous results are often more useful than a single isolated measurement.

Do You Need to Fast?

Many Korean health checkup centers instruct patients to fast overnight, commonly for approximately 8–12 hours.

For routine blood testing, fasting is mainly relevant to:

• Fasting glucose
• Triglycerides and, in some cases, calculated LDL cholesterol

A lipid profile can often be interpreted without fasting. However, triglycerides may rise after eating, and significantly elevated triglycerides can affect some methods used to calculate LDL cholesterol.

Korean health screening centers commonly measure fasting glucose and lipids together after an overnight fast.

Most other routine blood tests do not require fasting by themselves.

Health checkups also frequently include abdominal ultrasound, upper endoscopy, sedation, or other examinations that require fasting. Centers therefore usually provide one fasting instruction for the entire checkup rather than separate instructions for each test.

Unless the center gives different instructions:

• Do not eat during the fasting period.
• Avoid alcohol.
• Avoid sweetened drinks, milk, juice, and coffee.
• Plain water is usually permitted.
• Avoid unusually strenuous exercise before the examination.

Do not stop prescribed medication without medical instructions.

People taking insulin or medications that can cause hypoglycemia should receive individualized instructions.

Tell the center if you accidentally ate before the examination. Most of the checkup may still be possible, but fasting-dependent results may need to be interpreted differently or repeated.

Complete Blood Count

A complete blood count, or CBC, measures the major cellular components of blood.

It commonly includes:

• White blood cell count
• Red blood cell count
• Hemoglobin
• Hematocrit
• Platelet count
• Red blood cell indices such as MCV, MCH, and MCHC

Some reports also include a differential count showing the different types of white blood cells.

Hemoglobin and Anemia

Hemoglobin carries oxygen in red blood cells.

A low hemoglobin level may indicate anemia.

Possible causes include:

• Iron deficiency
• Menstrual blood loss
• Gastrointestinal bleeding
• Vitamin B12 or folate deficiency
• Kidney disease
• Chronic disease or inflammation
• Bone marrow disorders
• Inherited blood conditions

The CBC can suggest the general pattern of anemia, but it usually cannot determine the cause by itself.

For example, a low MCV indicates that red blood cells are smaller than usual. Iron deficiency is a common cause, but inherited conditions such as thalassemia can produce a similar pattern.

Ferritin, iron studies, vitamin levels, or evaluation for blood loss may be needed.

A mildly low hemoglobin value should not automatically lead to iron supplementation without determining whether iron deficiency is actually present.

White Blood Cells

White blood cells are involved in immune and inflammatory responses.

A high white blood cell count may occur with:

• Infection
• Inflammation
• Physical stress
• Smoking
• Steroid use
• Certain blood disorders

A low count may occur with:

• Viral illness
• Medication effects
• Autoimmune disease
• Nutritional deficiency
• Bone marrow disorders
• Normal individual variation

A single mildly abnormal white blood cell count often requires comparison with previous results or repeat testing rather than an extensive immediate evaluation.

Platelets

Platelets help form blood clots.

A low platelet count can increase bleeding risk when sufficiently reduced.

A high platelet count may occur temporarily with:

• Infection
• Inflammation
• Blood loss
• Iron deficiency

Persistent or substantial abnormalities may require further evaluation.

Occasionally, platelets clump in the blood collection tube and produce a falsely low result. An unexpected low platelet count may therefore need to be confirmed.

Blood Glucose and HbA1c

Fasting glucose is commonly measured during Korean health checkups. Many private programs also include HbA1c.

Fasting Glucose

Fasting glucose measures the blood glucose concentration after an overnight fast.

It may be affected by:

• Recent food intake
• Acute illness
• Stress
• Poor sleep
• Steroid medication
• Alcohol
• Changes in physical activity

HbA1c

HbA1c reflects average glucose exposure over approximately the previous two to three months and does not require fasting.

However, HbA1c may be misleading when the relationship between red blood cells and glucose is altered.

Examples include:

• Some types of anemia
• Recent significant bleeding
• Blood transfusion
• Certain hemoglobin variants
• Conditions affecting red blood cell turnover
• Pregnancy

When HbA1c is unreliable, plasma glucose measurements may be preferred.

In a person without clear symptoms of diabetes, an abnormal screening result generally requires confirmation rather than diagnosis from a single measurement alone.

Fasting glucose and HbA1c provide related but different information, so looking at both can sometimes be useful.

Lipid Profile

A standard lipid profile usually includes:

• Total cholesterol
• LDL cholesterol
• HDL cholesterol
• Triglycerides

LDL Cholesterol

LDL cholesterol is an important contributor to atherosclerotic cardiovascular disease.

The appropriate LDL level should not be determined only by the laboratory reference range.

The desirable level depends on overall cardiovascular risk, including factors such as:

• Age
• Smoking
• Blood pressure
• Diabetes
• Kidney disease
• Previous heart attack or stroke
• Known atherosclerosis
• Family history

A result that is not marked abnormal by the laboratory may therefore still be higher than desirable for someone at high cardiovascular risk.

HDL Cholesterol

HDL is commonly called “good cholesterol,” but a high HDL level does not cancel out elevated LDL cholesterol or other cardiovascular risks.

It should be interpreted as part of the overall cardiovascular profile rather than as an isolated protective score.

Triglycerides

Triglycerides are particularly sensitive to recent food intake.

They may also be elevated with:

• Alcohol use
• High intake of refined carbohydrates
• Poorly controlled diabetes
• Obesity
• Certain medications
• Genetic conditions

This is the main reason fasting still matters when a traditional fasting lipid panel is performed.

Liver Blood Tests

Health checkup reports often group several tests under terms such as “liver function tests” or “liver panel.”

Common measurements include:

• AST
• ALT
• GGT
• ALP
• Total bilirubin
• Direct bilirubin in some panels
• Albumin
• Total protein

These tests do not all measure the same aspect of liver health.

AST, ALT, GGT, and ALP primarily help identify patterns of liver or biliary abnormality, while albumin provides different information, including the liver’s ability to produce proteins.

AST and ALT

AST and ALT are enzymes that may rise when liver cells are injured.

Common causes include:

• Metabolic dysfunction-associated steatotic liver disease
• Alcohol use
• Viral hepatitis
• Medication or supplement effects
• Strenuous exercise
• Muscle injury
• Other liver diseases

ALT is more closely associated with the liver, while AST is also present in skeletal muscle and other tissues.

Normal AST and ALT levels do not completely exclude liver disease, and a mild elevation does not identify the cause by itself.

GGT

GGT may rise with:

• Alcohol use
• Fatty liver
• Bile duct abnormalities
• Certain medications
• Other hepatobiliary conditions

An elevated GGT result alone does not prove excessive alcohol consumption.

ALP

ALP can originate from both the liver and bone.

An elevated level may occur with:

• Bile duct disease
• Increased bone turnover
• Growth in younger people
• Pregnancy
• Other conditions

GGT can sometimes help determine whether an elevated ALP is more likely to be hepatobiliary in origin.

Bilirubin

Bilirubin is produced during the breakdown of heme, much of which comes from aging red blood cells. It is transported to the liver, conjugated, and eventually excreted into bile.

Laboratory reports may distinguish between:

• Total bilirubin, or T-bil
• Direct bilirubin, or D-bil
• Indirect bilirubin

Total bilirubin includes both conjugated and unconjugated bilirubin.

Direct bilirubin largely represents conjugated bilirubin. Indirect bilirubin is commonly estimated by subtracting direct bilirubin from total bilirubin.

Many routine screening panels measure total bilirubin only. Direct bilirubin may be added when total bilirubin is elevated or when further evaluation of a liver or bile duct abnormality is needed.

Predominantly indirect bilirubin elevation may occur with conditions such as:

• Gilbert syndrome
• Hemolysis
• Impaired bilirubin conjugation

Predominantly direct bilirubin elevation is more suggestive of hepatobiliary disease or impaired bile excretion.

A mild isolated bilirubin elevation with otherwise normal results may have a very different meaning from bilirubin elevation accompanied by abnormal AST, ALT, ALP, or GGT.

Albumin and Total Protein

Albumin is produced by the liver, but a low albumin level is not specific to liver disease.

It may also occur with:

• Inflammation
• Malnutrition
• Kidney protein loss
• Fluid overload
• Other systemic illness

Total protein includes albumin and other circulating proteins, including immunoglobulins.

Albumin and total protein should therefore not be interpreted as liver tests in isolation.

Kidney Function Tests

Common blood measurements include:

• Creatinine
• Estimated glomerular filtration rate, or eGFR
• Blood urea nitrogen, or BUN

Creatinine

Creatinine is commonly used to assess kidney filtration, but its concentration is also influenced by:

• Muscle mass
• Age
• Recent meat intake
• Exercise
• Hydration
• Certain medications and supplements

A muscular person may have a relatively high creatinine despite normal kidney function.

Conversely, a person with very low muscle mass may have a normal-looking creatinine despite reduced kidney function.

eGFR

eGFR is an estimate of kidney filtration calculated from serum creatinine using a standardized equation.

It is generally more useful than interpreting the creatinine value alone.

A single reduced eGFR does not necessarily establish chronic kidney disease. Chronicity and other evidence of kidney damage are also important.

Urine testing, particularly urine albumin, may provide additional information when kidney disease is suspected.

BUN

BUN may be affected by:

• Kidney function
• Dehydration
• Protein intake
• Gastrointestinal bleeding
• Liver function
• Certain medications

A mildly elevated BUN by itself is often nonspecific.

Uric Acid

Uric acid is commonly included in many Korean private health checkup panels, although it is not part of every package.

A high uric acid level may occur with:

• Reduced kidney excretion
• Alcohol intake
• Obesity and metabolic disease
• Certain medications
• High cell turnover
• Genetic factors

An elevated uric acid level does not mean that a person currently has gout.

Many people with asymptomatic hyperuricemia never develop gout, so treatment decisions should not be based solely on whether the number is marked high.

Thyroid Function Tests

Thyroid testing is commonly available in private Korean health checkups.

The most useful initial test for primary thyroid dysfunction is generally TSH.

Depending on the package, tests may include:

• TSH
• Free T4
• T3
• Thyroid antibodies

TSH and Free T4

In primary hypothyroidism, TSH is usually elevated.

In primary hyperthyroidism, TSH is usually suppressed.

Free T4 helps determine the pattern and severity when TSH is abnormal.

Thyroid results may be affected by:

• Acute illness
• Pregnancy
• Thyroid medication
• Amiodarone
• Lithium
• Steroids
• Biotin supplements
• Other medications

Biotin supplements can interfere with some thyroid laboratory assays, so supplement use should be reported to the center.

Thyroid Antibodies

Thyroid antibodies may support the diagnosis of autoimmune thyroid disease.

However, a positive antibody result does not necessarily mean that thyroid hormone levels are abnormal or that treatment is required.

They are therefore not simply a more comprehensive version of TSH and free T4.

Hepatitis B Tests

Hepatitis B testing is commonly available in Korean health checkup programs but is not automatically included in every package.

Common markers include:

• HBsAg
• Anti-HBs, sometimes written HBsAb
• Total anti-HBc

HBsAg

HBsAg is the hepatitis B surface antigen.

A positive result generally indicates current hepatitis B infection, although interpretation depends on the clinical context.

Anti-HBs

Anti-HBs is the hepatitis B surface antibody.

A positive result generally indicates immunity following vaccination or previous infection.

Total Anti-HBc

Anti-HBc is the antibody to the hepatitis B core antigen.

It indicates previous exposure to hepatitis B and is not produced by vaccination alone.

For initial adult hepatitis B screening, a three-test panel consisting of HBsAg, anti-HBs, and total anti-HBc provides more complete information about current infection, previous exposure, and immunity.

Some Korean checkup programs measure only HBsAg and anti-HBs. This can identify surface-antigen positivity and surface-antibody status but does not provide the same information as the full three-marker panel.

Hepatitis C Tests

Hepatitis C screening generally begins with an anti-HCV antibody test.

A positive antibody result means that the person has been exposed to hepatitis C at some point.

It does not by itself prove that active infection is currently present.

Active infection is confirmed with HCV RNA testing.

Iron and Ferritin

Some comprehensive health checkups include tests such as:

• Ferritin
• Serum iron
• Total iron-binding capacity
• Transferrin saturation

Ferritin is commonly used to assess iron stores.

A low ferritin level strongly supports depleted iron stores.

However, ferritin can also rise with inflammation, liver disease, infection, and other conditions. Therefore, a normal or elevated ferritin value may occasionally be more difficult to interpret in someone with significant inflammation.

Iron studies are particularly useful when:

• The CBC suggests anemia
• Menstrual blood loss is substantial
• Iron deficiency is suspected
• Gastrointestinal blood loss is a concern

Vitamin D

Vitamin D testing is commonly offered as an optional test in Korean private screening programs.

A low level is frequently encountered, particularly in people with limited sunlight exposure.

However, vitamin D should not be treated as a general blood marker for fatigue, immunity, or overall health.

Testing may be more relevant in people with conditions such as:

• Osteoporosis
• Fragility fractures
• Malabsorption
• Certain kidney or liver disorders
• Other risk factors for vitamin D deficiency or bone disease

Pancreatic Enzymes

Some health checkup programs include amylase or lipase.

These enzymes are primarily useful when pancreatitis or another pancreatic disorder is clinically suspected.

A mild isolated elevation in an asymptomatic person is nonspecific.

Normal amylase and lipase also do not screen effectively for pancreatic cancer.

They should not be interpreted as pancreatic cancer blood tests.

ESR and High-Sensitivity CRP

Some private Korean health screening programs include ESR or high-sensitivity CRP.

They are not specific tests for a single disease.

ESR

The erythrocyte sedimentation rate, or ESR, is a nonspecific marker influenced by many factors, including:

• Inflammation
• Infection
• Anemia
• Age
• Pregnancy

An elevated ESR does not identify the cause of an abnormality.

High-Sensitivity CRP

High-sensitivity CRP, or hs-CRP, measures the same C-reactive protein measured by a standard CRP test, but the assay is designed to measure much lower concentrations more precisely.

Standard CRP is generally used when clinically significant inflammation or infection is being evaluated.

hs-CRP may be used as an additional cardiovascular risk marker in people who are not experiencing an acute inflammatory illness.

However, hs-CRP can also rise because of infection, injury, smoking, obesity, or other inflammatory conditions.

For this reason, an elevated hs-CRP should not automatically be interpreted as cardiovascular disease.

Tumor Markers

Tumor marker panels are frequently offered in Korean private health checkups.

The markers most commonly encountered are:

• AFP
• CEA
• CA 19-9
• CA 125 in women
• PSA in men

Some programs also offer additional markers such as:

• PIVKA-II
• CA 15-3
• CYFRA 21-1
• NSE
• Other selected tumor markers

The term “tumor marker” can create two common misconceptions:

• A normal tumor marker means that cancer is absent.
• An elevated tumor marker means that cancer is present.

Neither is correct.

Many tumor markers can remain normal despite cancer and can become elevated because of benign conditions.

Most are therefore not suitable as stand-alone cancer screening tests in healthy people.

AFP

AFP is associated particularly with hepatocellular carcinoma but may also be abnormal in other conditions.

It can be useful in selected people at increased risk of liver cancer, especially when combined with appropriate liver imaging.

A normal AFP result does not exclude liver cancer.

CEA

CEA may be elevated in several cancers but may also be elevated in smokers and various benign conditions.

It is generally more useful for monitoring selected patients with known cancer than as a screening test in healthy adults.

CA 19-9

CA 19-9 is associated with pancreatic and biliary cancers but may also rise with benign conditions such as:

• Bile duct obstruction
• Cholangitis
• Pancreatitis

Some people genetically produce little or no CA 19-9.

A normal CA 19-9 does not exclude pancreatic cancer, and an elevated value does not diagnose it.

CA 125

CA 125 is associated with ovarian cancer but can also rise with benign conditions, including:

• Menstruation
• Endometriosis
• Uterine fibroids
• Pregnancy
• Pelvic inflammation
• Liver disease

CA 125 is not an effective stand-alone ovarian cancer screening test for women at average risk.

PSA

PSA differs somewhat from most other tumor markers because it can have a role in prostate cancer screening.

However, PSA is not specific for cancer.

It may also rise with:

• Benign prostate enlargement
• Prostatitis
• Urinary retention
• Recent prostate manipulation
• Recent sexual activity

PSA screening can lead to further imaging or biopsy and carries the possibility of false-positive results, overdiagnosis, and overtreatment.

The decision to test should therefore consider age, family history, individual risk, general health, and personal preferences.

Additional Tumor Markers

Markers such as PIVKA-II, CA 15-3, CYFRA 21-1, and NSE may appear in premium or organ-specific Korean health screening packages.

They are not required in every general health checkup.

For example, CA 15-3 is mainly used in selected patients with known breast cancer and does not replace mammography or breast ultrasound.

Adding more tumor markers does not necessarily improve cancer screening.

Other Optional Blood Tests

Premium health checkups may offer additional tests such as:

• Insulin
• Apolipoproteins
• Lipoprotein(a)
• Homocysteine
• Autoimmune antibodies
• Sex hormones
• Testosterone
• Cortisol
• Allergy panels
• Micronutrient panels

Some may be useful for a specific person or clinical question, but they should not automatically be considered better simply because they are included in a more expensive package.

Broad testing increases the chance of borderline or unexplained abnormalities that may lead to repeated testing and unnecessary follow-up.

A useful question before adding an optional blood test is:

What would I do differently if this result were abnormal?

If there is no clear answer, the value of the test may be limited.

Why Reference Ranges Differ

Laboratories may use different:

• Analyzers
• Reagents
• Measurement methods
• Units
• Reference populations
• Calculation formulas

Reference ranges can therefore differ between hospitals and screening centers.

Use the reference range provided by the laboratory that performed the test.

When comparing results from different countries or different centers, check:

• The unit
• The assay method when relevant
• Whether the sample was fasting
• The laboratory reference range

This is particularly important for thyroid tests, tumor markers, hormones, and antibody measurements.

Common Abbreviations on Korean Health Checkup Reports

Foreign patients may receive reports containing a mixture of Korean terminology and English abbreviations.

Common examples include:

• CBC: complete blood count
• WBC: white blood cell count
• RBC: red blood cell count
• Hb or Hgb: hemoglobin
• Hct: hematocrit
• PLT: platelet count
• MCV: mean corpuscular volume
• FBS or FPG: fasting blood sugar or fasting plasma glucose
• HbA1c: glycated hemoglobin
• TC: total cholesterol
• TG: triglycerides
• HDL-C: HDL cholesterol
• LDL-C: LDL cholesterol
• AST: aspartate aminotransferase
• ALT: alanine aminotransferase
• GGT or γ-GTP: gamma-glutamyl transferase
• ALP: alkaline phosphatase
• T-bil: total bilirubin
• D-bil: direct bilirubin
• BUN: blood urea nitrogen
• Cr: creatinine
• eGFR: estimated glomerular filtration rate
• UA: uric acid
• TSH: thyroid-stimulating hormone
• FT4 or free T4: free thyroxine
• HBsAg: hepatitis B surface antigen
• HBsAb or anti-HBs: hepatitis B surface antibody
• HBcAb or anti-HBc: hepatitis B core antibody
• HCV Ab or anti-HCV: hepatitis C antibody
• ESR: erythrocyte sedimentation rate
• hs-CRP: high-sensitivity C-reactive protein

Abbreviations can occasionally vary between laboratories, so check the test category and units shown on the report.

Borderline Abnormal Results

Comprehensive health checkups may measure dozens of different values.

Even in a healthy person, one or more results may be slightly outside the laboratory reference range.

Examples commonly encountered during screening include:

• Mildly elevated liver enzymes
• Borderline glucose
• Slightly reduced white blood cell count
• Mild isolated bilirubin elevation
• Borderline TSH
• Mildly elevated uric acid
• A small change in creatinine
• Mildly elevated hs-CRP
• A nonspecific tumor marker elevation

The appropriate next step may be:

• No further action
• Lifestyle modification
• Comparison with previous results
• Repeat testing
• A more specific laboratory test
• Imaging
• Primary care or specialist evaluation

Not every abnormal result requires immediate extensive investigation.

At the same time, persistent or substantial abnormalities should not be ignored simply because there are no symptoms.

When Blood Tests Are Not Enough

Blood tests provide important information, but they cannot replace imaging, endoscopy, physical examination, or established cancer screening methods.

For example:

• Normal liver enzymes do not exclude fatty liver or significant chronic liver disease.
• Normal pancreatic enzymes and CA 19-9 do not exclude pancreatic cancer.
• Normal tumor markers do not exclude cancer.
• A normal-looking creatinine does not always exclude reduced kidney function.
• Normal thyroid function does not exclude a thyroid nodule.
• Normal hemoglobin does not necessarily mean iron stores are adequate.

Tumor marker panels should not replace established cancer screening examinations.

What to Ask When Booking

Before selecting a blood test package, ask:

• Which exact tests are included?
• Does the diabetes testing include HbA1c as well as fasting glucose?
• Does the lipid profile include LDL, HDL, and triglycerides?
• Which hepatitis B markers are included?
• Is hepatitis C testing included?
• Does the thyroid panel include TSH only or additional tests?
• Are ferritin and iron studies included?
• Which tumor markers are included?
• How long should I fast?
• Can I drink water?
• How should I take my regular medication on the morning of the examination?
• Will the report include numerical results, units, and reference ranges?
• Is an English report available?
• Is consultation available if an abnormality is found?

Do not rely only on package names such as “basic,” “premium,” “cancer,” or “anti-aging.”

The actual test list is more important than the package name.

Tips for Foreigners

Bring a list of medications and supplements, including products purchased outside Korea.

Bring previous laboratory reports when available. The original values, dates, units, and reference ranges are more useful than simply saying that a previous test was “normal.”

Confirm whether the center can provide:

• Preparation instructions in English
• An English laboratory report
• An English-speaking medical consultation
• Electronic or printed copies of the numerical results

Be careful when comparing Korean results with tests performed abroad.

Glucose, cholesterol, creatinine, thyroid hormones, and other measurements may use different units in different countries. Confirm the unit before comparing the numbers directly.

Final Thoughts

Blood tests are an important part of health screening, but more testing is not always better.

The most useful general screening panels usually assess:

• Blood cells
• Glucose regulation
• Lipids and cardiovascular risk
• Liver abnormalities
• Kidney function

Other tests—including thyroid tests, hepatitis testing, iron studies, vitamin D, hs-CRP, and tumor markers—may be added depending on the health screening program and individual circumstances.

For routine blood testing, overnight fasting is mainly relevant to fasting glucose and triglycerides. Many of the other blood tests included in a health checkup do not require fasting by themselves.

Blood test results should be interpreted as patterns and trends rather than isolated numbers marked in red.

Medication, supplements, temporary illness, laboratory methods, previous results, and individual risk all matter.

Tumor markers deserve particular caution. AFP, CEA, CA 19-9, CA 125, and PSA are commonly encountered in Korean private health checkups, but most should not be interpreted as stand-alone cancer screening tests.

Choose additional blood tests according to a clear purpose rather than simply selecting the package with the largest number of items.

Have a general question about health checkups in Korea? Feel free to reach out through our Contact page. Please do not submit personal medical information or urgent medical questions.