Liver Alkaline Phosphatase (ALP) Blood Test
A blood test that measures alkaline phosphatase (ALP), an enzyme made mainly by your liver and bones, to help your doctor check how well your liver is working and find out whether symptoms you may be having are related to liver disease or a bone disorder. The results can guide any further testing or treatment decisions.
{"Alkaline phosphatase is an enzyme mainly made in the liver and bones","Elevated levels may indicate liver damage, bone disease, or other conditions","The test is performed on a blood sample taken from your arm","Certain medications, pregnancy, or growing bones can affect results","Your doctor will interpret results based on your overall health and other tests"}
Key facts at a glance
- LOINC
- 40795-7
- Short code
- ALP
- Synonyms
- ALP Liver 2 SerPl Ql
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST/gold top) or plain red top tube
- Units
- not specified
- Ref low
- 44
- Ref high
- 147
- Critical range
- — – 500 not specified
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Spectrophotometry with p-nitrophenyl phosphate substrate
- CPT
- 84075
- SNOMED
- 271509001
- Specimen volume
- 1.0-2.0 mL of serum minimum
- Stability
- Room temperature (20-25°C): 7 days; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 1–24 hours
- Order
- routine
What is this test?
The Liver Alkaline Phosphatase test measures the amount of alkaline phosphatase (ALP) in your blood. ALP is an enzyme—a type of protein that helps speed up chemical reactions in your body. While ALP is found throughout the body, it is primarily produced in the liver, bones, intestines, and kidneys. This test specifically focuses on the liver-derived form of ALP.
Why is it performed?
Your doctor may order this test as part of a routine liver function panel or if you have symptoms of liver disease such as jaundice (yellowing of skin or eyes), abdominal pain, nausea, or unexplained fatigue. The test helps determine if your liver is functioning properly or if there is damage to liver cells. It can also help distinguish between liver and bone disorders when elevated ALP levels are detected.
How is the test done?
A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The blood is collected into a tube and sent to a laboratory for analysis. You do not need to fast before this test, though your doctor may instruct you to do so based on other tests being performed at the same time. The procedure typically takes only a few minutes.
What do the results mean?
Normal ALP levels vary by age, sex, and laboratory reference ranges. Generally, adults have lower ALP levels than growing children and adolescents. High ALP levels may indicate liver diseases such as hepatitis, cirrhosis, bile duct obstruction, or gallstones. They can also signal bone disorders like Paget's disease, bone fractures, or certain cancers. Low ALP levels are less common but may occur in malnutrition, zinc deficiency, or certain genetic disorders.
Reference range
Negativenot specified
No special preparation or fasting required
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated liver alkaline phosphatase is a key indicator of cholestasis—a condition where bile flow from the liver is reduced or blocked. This can result from gallstones, liver inflammation (hepatitis), primary biliary cholangitis, or tumors pressing on bile ducts. The test is often interpreted alongside other liver enzymes (ALT, AST, GGT, bilirubin) to determine whether liver injury is primarily hepatocellular or cholestatic in nature. In bone diseases, elevated ALP reflects increased bone remodeling activity, particularly in conditions with high bone formation rates.
Frequently asked questions
Do I need to fast before the test?
Can medications affect my ALP results?
Is a high ALP level always serious?
How is the liver ALP test different from bone ALP?
What happens if my ALP is low?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 10, 2026. · Read our editorial policy