What are liver function tests?
Liver function tests, also called a liver panel or hepatic panel, are a group of blood tests with a variable composition. They may include enzymes, bilirubin, and blood proteins.
Liver function tests, also called a liver panel or hepatic panel, are a group of blood tests with a variable composition. They may include enzymes, bilirubin, and blood proteins.
Not every component directly measures liver function. Some values are more closely associated with cell injury, while others provide information about bile flow, bilirubin metabolism, or protein synthesis.
What do liver function tests show?
A liver panel can reveal patterns involving liver-related enzymes, bile duct-related enzymes, bilirubin, and proteins. These patterns may help guide further assessment but do not identify a specific diagnosis on their own.
A liver panel can reveal patterns involving liver-related enzymes, bile duct-related enzymes, bilirubin, and proteins. These patterns may help guide further assessment but do not identify a specific diagnosis on their own.
| Group | Common tests | What they may reflect |
|---|---|---|
| Cell-associated enzymes | ALT, AST | Enzymes that may rise with cell injury; AST is not specific to the liver |
| Cholestatic enzymes | Alkaline phosphatase, ALP; gamma-glutamyl transferase, GGT | Values assessed in the context of the liver and bile ducts |
| Bilirubin | Total, direct, and indirect bilirubin | Bilirubin production, processing, and excretion |
| Proteins | Albumin, total protein, sometimes globulins and A/G ratio | Protein synthesis and overall protein balance in a broader context |
| Additional tests | Prothrombin time or INR and other selected tests | Information used for specific clinical purposes and not included in every panel |
When are liver function tests ordered?
Liver-related tests may be ordered to investigate symptoms, monitor a known condition, assess medicine safety, evaluate an abnormal result, or as part of a broader blood chemistry panel.
Liver-related tests may be ordered to investigate symptoms, monitor a known condition, assess medicine safety, evaluate an abnormal result, or as part of a broader blood chemistry panel.
| Situation | Why the tests may be useful |
|---|---|
| Yellowing of the skin or eyes, dark urine, pale stools, itching, or upper abdominal discomfort | To assess bilirubin and liver- or bile-related patterns |
| Nausea, fatigue, reduced appetite, or unexplained symptoms | As part of a broader assessment |
| Use of medicines that may affect liver-related values | To monitor safety when indicated |
| Known liver or bile duct condition | To monitor changes over time |
| Alcohol use, metabolic risk factors, or exposure to viral hepatitis | To assess relevant laboratory values within a broader evaluation |
| Abnormal ALT, AST, ALP, GGT, or bilirubin | To repeat and expand the assessment |
| Before a procedure or treatment | To obtain baseline information when required |
How to prepare for liver function tests
Preparation depends on the exact panel and the other blood tests collected at the same time. A clinician or laboratory may request fasting.
Preparation depends on the exact panel and the other blood tests collected at the same time. A clinician or laboratory may request fasting.
| Question | Recommendation |
|---|---|
| Do I need to fast? | Follow the instructions for the specific panel. Fasting may be required when the tests are part of a broader blood chemistry group |
| Can I drink water? | During prescribed fasting, plain water is usually allowed |
| What about medicines? | Tell the clinician or laboratory about all medicines and supplements. Do not stop them on your own |
| What about alcohol? | Follow the clinician or laboratory’s preparation instructions because alcohol may affect some values |
| Can I exercise? | Intense exercise can affect AST and other values. Mention recent unusual exercise when relevant |
| What time should I take the test? | Follow the instructions for the panel and use similar conditions for repeat monitoring |
Before attending the laboratory, confirm:
What is included in a liver panel?
The exact composition varies. Products called “liver function tests,” “liver panel,” “hepatic panel,” or “hepatogram” may contain different combinations.
The exact composition varies. Products called “liver function tests,” “liver panel,” “hepatic panel,” or “hepatogram” may contain different combinations.
| Group | Common tests | What they reflect |
|---|---|---|
| Cell-associated enzymes | ALT and AST | Enzymes that may rise with cell injury; AST is also found in muscle and other tissues |
| Cholestatic enzymes | ALP and GGT | Values interpreted in the context of the liver and bile ducts |
| Bilirubin | Total, direct, and indirect bilirubin | Bilirubin metabolism; the available fractions depend on the panel |
| Proteins | Albumin, total protein, sometimes globulins and A/G ratio | Protein synthesis and balance, with possible influence from other organs and conditions |
| Additional tests | Prothrombin time or INR, LDH, and other tests | May be ordered separately and are not included in every panel |
Packages with the same general name should not be compared without reviewing their full composition.
Adult liver test reference ranges
There is no single universal “normal liver panel.” Each component has its own reference range, which depends on the laboratory method, sex, age, and other factors.
There is no single universal “normal liver panel.” Each component has its own reference range, which depends on the laboratory method, sex, age, and other factors.
The following are examples of adult ranges from one NHS laboratory service.
| Test | Example adult range | Units |
|---|---|---|
| ALT | 10–50 | U/L |
| Alkaline phosphatase, ALP | 30–130 | U/L |
| Total bilirubin | <21 | µmol/L |
| Albumin | 35–50 | g/L |
| Total protein | 60–80 | g/L |
| GGT, men | 10–71 | U/L |
| GGT, women | 6–42 | U/L |
Why AST is not included in one universal example table
AST is not included in every liver panel, laboratory limits vary, and the enzyme is not specific to the liver. When AST is reported, use the reference range printed by the testing laboratory.
Important points:
How to interpret liver function tests
Interpret the panel as a pattern rather than one enzyme at a time. ALT and AST are more closely associated with cell injury. ALP and GGT help assess a possible cholestatic or bile duct-related pattern. Bilirubin reflects production, processing, and excretion, while albumin provides different information about protein synthesis in a broader clinical context.
Interpret the panel as a pattern rather than one enzyme at a time. ALT and AST are more closely associated with cell injury. ALP and GGT help assess a possible cholestatic or bile duct-related pattern. Bilirubin reflects production, processing, and excretion, while albumin provides different information about protein synthesis in a broader clinical context.
Step-by-step approach
- Check the panel composition and laboratory reference ranges.
- Compare ALT and AST.
- Review ALP together with GGT.
- Review total and direct bilirubin when both are available.
- Review albumin, total protein, and INR if it was ordered.
- Consider symptoms, alcohol use, medicines, supplements, exercise, and other conditions.
- If a result is unexpected, repeat testing or additional investigations may be needed.
Common patterns
| Pattern | What may need clarification |
|---|---|
| ALT and AST are the main elevated values | Possible liver cell injury, but medicines, alcohol, muscle injury, and other causes are also considered |
| High ALP with high GGT | More supportive of a liver or bile duct source of ALP |
| High ALP with normal GGT | May require assessment for bone or another non-liver source |
| High bilirubin | Possible changes in bilirubin production, conjugation, or excretion; fractions and other values matter |
| Low albumin | May be associated with liver, kidney, nutrition, inflammation, or protein loss |
| Abnormal enzymes together with bilirubin | Requires a combined assessment rather than one automated conclusion |
| Normal enzymes | Does not rule out every liver condition |
Individual tests
A liver panel should not be used by itself to diagnose hepatitis or fatty liver disease, identify alcohol as the cause, recommend a “detox,” or advise stopping prescribed medicine.
What additional tests may be ordered?
Liver tests show a laboratory pattern but usually do not establish its cause. Further testing depends on which values are abnormal, symptoms, and risk factors.
Liver tests show a laboratory pattern but usually do not establish its cause. Further testing depends on which values are abnormal, symptoms, and risk factors.
| Situation | Additional tests | Purpose |
|---|---|---|
| High ALT or AST | Repeat liver panel, creatine kinase when muscle injury is possible, and hepatitis tests | To confirm the result and assess possible sources |
| High ALP and GGT | Ultrasound of the liver and bile ducts, bilirubin, and other tests | To assess a possible cholestatic pattern |
| High ALP with normal GGT | Calcium, phosphate, vitamin D, and other bone-related values | To assess a possible non-liver source |
| High bilirubin | Direct and indirect bilirubin, CBC, reticulocyte count, and other tests | To distinguish liver, bile duct, and hemolytic causes |
| Low albumin | Urine protein or UACR, kidney-related tests, nutrition, and inflammatory context | To assess production and possible protein loss |
| Possible chronic liver disease | INR or prothrombin time, CBC, imaging, and specialized tests | To provide a broader assessment |
| High ferritin or relevant family history | Transferrin saturation and other iron studies | To assess possible iron overload |
| Possible autoimmune process | Selected antibodies and immunoglobulins | Specialized tests used in the appropriate clinical context |
How much do liver function tests cost?
The price depends on panel composition. Different laboratories may include ALT, AST, bilirubin, GGT, alkaline phosphatase, albumin, and other tests in different combinations.
The price depends on panel composition. Different laboratories may include ALT, AST, bilirubin, GGT, alkaline phosphatase, albumin, and other tests in different combinations.
When comparing offers, check:
If panel compositions differ, compare the individual tests or select an equivalent set before comparing total prices.
How much does this test cost?
Price depends on city, laboratory, panel composition, and blood collection fee. Compare equivalent offers and total cost.
A single minimum price is hidden until panel composition normalization.
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Authorship, sources, and limitations
This material explains the laboratory test, preparation, and result interpretation principles. For your own report, prioritize the exact test name, units, and reference ranges printed by your laboratory.
- MedlinePlus — Liver Function Tests
- MedlinePlus — ALT Blood Test
- MedlinePlus — AST Test
- MedlinePlus — Alkaline Phosphatase
- MedlinePlus — Gamma-Glutamyl Transferase (GGT) Test
- MedlinePlus — Bilirubin Blood Test
- MedlinePlus — Albumin Blood Test
- Gloucestershire Hospitals NHS — Liver Function Tests
This material and Vitametria automated explanation are informational only and are not a diagnosis, medical opinion, or treatment recommendation.
Prices, panel composition, turnaround times, and promotional terms may change. Verify current details before payment.