Comprehensive Liver Function Panel
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Quick Guide
A liver function test (LFT) measures proteins and enzymes in your blood to check how well your liver is working. This panel covers 12 markers across three tests from a single blood draw, processed at a CLIA-certified (Clinical Laboratory Improvement Amendments) lab.
| Detail | Value |
|---|---|
| Sample type | Blood |
| Collection method | In-person at a lab or clinic |
| Turnaround time | Typically one to three business days |
| Fasting required | Not always required; check your full order |
| Age requirement | 18 or older |
If you’ve had fatigue, yellowing of the skin or eyes, dark urine, or stomach pain, this test helps figure out whether your liver is involved. Tell your provider about any medications or supplements you take, since some can shift your results. If you’re on a long-term medication known to affect the liver, like a statin or methotrexate, this test is often part of routine monitoring.
About the Liver Function Test
Purpose of the test
The liver function test looks for signs of liver damage, disease, or stress before symptoms show up. Many liver conditions don’t cause noticeable symptoms early on, so this test catches problems a physical exam alone would miss.
Your liver handles over 500 tasks. It filters blood, breaks down food, removes toxins, makes proteins for blood clotting, and regulates blood sugar. When something goes wrong, the markers on this panel shift in ways that point toward specific types of problems.
Liver function tests are most often used to help find out if liver disease or damage could be causing certain symptoms, learn how serious liver disease is after it has been diagnosed, monitor liver disease over time, and check for side effects of certain medicines that can affect the liver, according to the MedlinePlus. Conditions this test helps evaluate include metabolic dysfunction-associated steatotic liver disease (MASLD, formerly called nonalcoholic fatty liver disease), viral hepatitis, alcohol-related liver disease, autoimmune liver conditions, and drug-induced liver injury (DILI).
The test serves two purposes:
- Diagnosis: Consider testing if you have jaundice (yellowing of the skin or eyes), stomach pain, dark urine, light-colored stool, or unexplained fatigue.
- Monitoring: Tracks liver health over time if you have a known liver condition or take hepatotoxic (liver-stressing) medications like statins, methotrexate, antifungals, or antiepileptics.
This test doesn’t diagnose a specific liver disease on its own. Your provider reads results alongside your symptoms, history, and sometimes imaging like an ultrasound.
What does the liver function test measure?
This panel covers 12 markers across three tests from a single blood sample at a CLIA-certified lab.
- Hepatic Function Panel: 10-component panel measuring:
- Total Protein: The combined amount of albumin and globulin proteins in your blood.
- Albumin: The liver’s main blood protein, which carries hormones and keeps fluid inside blood vessels.
- Globulin (calculated): Total protein minus albumin; reflects proteins involved in immune function and blood clotting.
- Albumin/Globulin Ratio (calculated): Compares albumin to globulin to spot imbalances between these two protein groups.
- Total Bilirubin: The total amount of bilirubin, a yellow waste product made when red blood cells break down.
- Direct Bilirubin: The portion of bilirubin the liver has processed and attached to sugar (conjugated).
- Indirect Bilirubin (calculated): Total minus direct bilirubin; reflects the unprocessed form not yet handled by the liver.
- Alkaline Phosphatase: An enzyme found mainly in the liver and bones that rises when bile flow is blocked or liver cells are damaged.
- AST: Aspartate aminotransferase, an enzyme in the liver and other tissues that spills into the blood when cells are damaged.
- ALT: Alanine aminotransferase, an enzyme found mainly in liver cells that rises when the liver is injured.
- Gamma Glutamyl Transferase (GGT): An enzyme in the liver that helps remove harmful substances and rises with liver stress or alcohol use.
- Lactate Dehydrogenase (LD): An enzyme found in tissues throughout the body, released into the blood when cells are damaged.
When should I get a liver function test?
Consider testing if any of these apply:
- Yellowing of the skin or eyes (jaundice)
- Stomach pain, especially in the upper right side
- Dark-colored urine or light-colored stool
- Unexplained fatigue or nausea
- A known risk factor for liver disease (obesity, type 2 diabetes, heavy alcohol use)
- Long-term use of a medication that can affect the liver
- A family history of liver disease or a genetic liver condition
- Exposure to hepatitis B or hepatitis C
If you’re experiencing yellowing of the eyes or skin right now, see a provider right away. Don’t wait for a routine test result. That symptom can signal a condition needing urgent care.
No major guideline recommends universal LFT screening by age alone. Testing is driven by risk factors, including:
- Obesity, type 2 diabetes, or metabolic syndrome, which raise the risk for MASLD. MASLD (also referred to as nonalcoholic fatty liver disease, or NAFLD) is a condition in which excess fat builds up in your liver, as described by the NIDDK.
- Heavy or long-term alcohol use
- Long-term hepatotoxic medications (statins, methotrexate, antifungals, antiepileptics, tuberculosis drugs)
- A personal or family history of viral hepatitis, hemochromatosis, Wilson’s disease, or alpha-1 antitrypsin deficiency
- A prior abnormal liver result that needs follow-up
- Private Results in a Secure Online Portal
- Thousands of CLIA-Certified U.S. Labs
- Results Typically Ready in 1 to 3 Business Days
- Upfront pricing, no surprise bills
How It Works
How to get tested
You can order the Liver Function Test (LFT) yourself online, with no doctor visit or referral needed. A licensed physician reviews and authorizes your order as part of the process. Most results are ready in one to three business days and appear in your secure online account.
Before the test
Fasting is not always required, but your provider may ask you to fast if this test is ordered alongside others such as a lipid panel or glucose test. Check your full order before your appointment.
Tell your provider about every medication and supplement you take. Many things can affect your ALT results, such as your age, sex, weight, and certain medicines and dietary supplements, and ALT levels can also be affected by intense exercise, according to MedlinePlus’s ALT blood test resource. Your provider will decide whether to pause any medications before testing.
Heavy alcohol use and intense exercise in the day or two before the draw can raise AST and ALT temporarily. Neither will ruin your results, but both can push borderline values higher.
During the test
- Check in at the lab or clinic with a photo ID and any order from your provider.
- A phlebotomist cleans a spot on your inner arm and draws blood from a vein. You’ll feel a brief pinch.
- The sample goes into a vial and is sent to the lab. A small bandage covers the draw site.
The visit takes about 15 minutes. Some people notice mild bruising over the next day or two. That’s normal. Call your provider if you have lasting pain, swelling, or any sign of infection at the site.
After the test
Results are typically ready within one to three business days after the lab receives your sample, though timing can vary by lab. You’ll usually get them in your secure online account. If results fall outside the expected range, some providers will reach out directly.
What Do My Results Mean?
Each marker is reported as a number in units per liter (U/L) or grams per deciliter (g/dL). Your report shows your value next to a reference range. Reading the whole panel together gives a clearer picture than any single marker alone.
Reference ranges vary by lab, age, and sex. The table below shows approximate adult ranges based on Mayo Clinic’s liver function test reference values. Your report’s ranges are the ones that apply to you.
| Marker | Approximate Adult Reference Range | What it reflects |
|---|---|---|
| ALT | 7 to 56 U/L | Liver cell health |
| AST | 10 to 40 U/L | Liver and other tissue health |
| Alkaline Phosphatase | 44 to 147 U/L | Bile duct and bone health |
| Total Bilirubin | 0.1 to 1.2 mg/dL | Red blood cell breakdown and liver processing |
| Direct Bilirubin | 0 to 0.3 mg/dL | Liver’s ability to process bilirubin |
| Albumin | 3.5 to 5.0 g/dL | Liver protein production |
| Total Protein | 6.3 to 8.2 g/dL | Overall protein balance |
| GGT | Varies by age and sex (see lab report) | Liver stress, bile flow, alcohol use |
| LD | Varies by age and sex (see lab report) | Tissue damage across the body |
Ranges are approximate and vary by lab. Use the reference range on your own report.
If your results are normal
All markers fall within the reference ranges on your report. That’s a good sign. It means no obvious stress or damage showed up in this snapshot, though it doesn’t rule out every liver condition.
If you had the test because of symptoms that haven’t gone away, your provider may want to recheck or look at other causes. One normal result doesn’t always close the book.
If your results are high
High ALT and AST together are the clearest signal of liver cell damage. The higher the values and the longer they stay high, the more likely something ongoing is driving them. Common causes include MASLD, viral hepatitis, alcohol-related liver disease, DILI, and autoimmune hepatitis.
Liver function tests are blood tests that measure different substances produced by your liver, including proteins, enzymes, and bilirubin. Values that are higher or lower than normal may indicate disease, as explained by Cleveland Clinic. A few things can push ALT and AST up temporarily without serious disease: intense exercise, acetaminophen use, certain supplements, or a recent illness. Mildly high values often get rechecked in four to six weeks.
High ALP with normal or mildly high ALT and AST points more toward bile duct problems or bone disease than liver cell injury. ALP, ALT, AST, and GGT are enzymes that are mainly made in your liver, and high GGT alongside high ALP makes a bile duct cause more likely, per MedlinePlus.
High bilirubin with otherwise normal markers can suggest a problem with how your body processes bilirubin, not necessarily liver cell damage. Low albumin or low total protein, especially when other markers are off too, can mean the liver isn’t making proteins well enough.
Your provider looks at the full pattern, not one number. Follow-up often includes hepatitis B and C serology, imaging like an ultrasound, or a repeat panel in four to six weeks.
If your results are low
Low albumin is the most significant low result on this panel. Values that are higher or lower than normal may indicate disease. Low albumin can mean the liver isn’t producing enough protein, which may point to chronic liver disease, malnutrition, or inflammation. Low total protein follows a similar pattern.
Low LD isn’t usually a concern. Low ALP can occasionally show up with certain nutritional deficiencies but is less commonly flagged.
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- Private Results in a Secure Online Portal
- Thousands of CLIA-Certified U.S. Labs
- Results Typically Ready in 1 to 3 Business Days
- Upfront pricing, no surprise bills
Sources
- MedlinePlus. Liver Function Tests. 2023.
- MedlinePlus. ALT Blood Test. 2023.
- MedlinePlus. AST Test. 2023.
- MedlinePlus. Gamma-Glutamyl Transferase (GGT) Test. 2023.
- Cleveland Clinic. Liver Function Tests: Types, Purpose & Results Interpretation. 2022.
- Cleveland Clinic. Liver Disease: Signs & Symptoms, Causes, Stages, Treatment. 2025.
- Mayo Clinic. Liver Function Tests. 2025.
- Mayo Clinic. Liver Problems: Symptoms and Causes. 2025.
- NIDDK. Definition & Facts of NAFLD & NASH. 2021.
- CDC National Center for Health Statistics. Chronic Liver Disease or Cirrhosis. 2025.
Frequently Asked Questions
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What causes a liver function test to be high?
Several things can raise liver enzyme levels. The most common causes of persistently high ALT and AST include MASLD, viral hepatitis, heavy alcohol use, and medications or supplements that stress the liver. Temporary spikes can come from intense exercise, acetaminophen, or a recent illness. Mildly high results don’t always mean serious disease, but they do need follow-up.
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What enzymes are measured in a liver function test?
This panel measures four enzymes: ALT (alanine aminotransferase), AST (aspartate aminotransferase), alkaline phosphatase (ALP), and GGT (gamma glutamyl transferase). ALT and AST are the primary markers for liver cell damage. ALP and GGT are more closely tied to bile duct function and liver stress from alcohol or metabolic causes.
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What is a normal liver function test level?
Normal ranges vary by lab, age, and sex, so use the range printed on your own report. Liver function tests use a sample of your blood to measure several substances made by your liver, and as a general guide from MedlinePlus, results are interpreted alongside your symptoms and history rather than as standalone numbers.
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Is the liver function test the same as a comprehensive metabolic panel?
No, but there’s overlap. A comprehensive metabolic panel (CMP) includes liver markers like ALT, AST, ALP, bilirubin, albumin, and total protein, along with kidney markers, electrolytes, and glucose. The LFT focuses on liver-related markers and goes deeper, adding GGT and lactate dehydrogenase (LD). If you’ve had a CMP at a routine physical, you’ve already seen some of the same liver markers.
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Can cirrhosis or liver fibrosis be reversed?
Fibrosis (scarring of liver tissue) can improve if caught early and the cause is treated. The inflammation and liver damage of NASH can cause fibrosis, or scarring, of the liver. NASH may lead to cirrhosis, in which the liver is scarred and permanently damaged. Early cirrhosis may improve when the cause is addressed, but late-stage cirrhosis rarely does. That’s why catching liver stress early matters.
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Do I need to fast before a liver function test?
Fasting is not always required for this panel. However, if your provider ordered this test alongside a lipid panel or glucose test, fasting may be required for those. Check your full order before you go and follow any instructions your provider gives you.
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How do I improve my liver function test results?
There’s no quick fix, but several things can bring high markers down over time: reducing or stopping alcohol, losing weight if you’re carrying excess body fat, and treating a condition like hepatitis or diabetes. Don’t stop any prescription medication on your own. Talk with your provider about what’s driving your results before making changes.
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Will anyone see my results besides me?
Your results go to your secure online account. You can download or print them to share with your own doctor. The lab that runs your test and the ordering provider may also see your results. Our Privacy Policy explains how we handle your information.
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Can I use insurance to pay for this test?
Testing.com does not bill insurance, so no insurance claim is created. You can pay with HSA or FSA funds, and we can provide an itemized receipt if you want to request reimbursement.
