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Alkalinephosphataseproto

Published: July 31, 2026Updated: August 10, 2026

A blood test that measures the level of alkaline phosphatase, an enzyme found mainly in the liver and bones, to help evaluate liver and bone health.

Quick summary

{"Alkaline phosphatase is an enzyme primarily produced in the liver and bones","Elevated levels may indicate liver disease, bone disorders, or bile duct obstruction","The test requires a simple blood draw, usually after fasting","Certain medications, pregnancy, and growing bones can affect results","Your healthcare provider will interpret results based on your overall health"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 10, 2026Editorial policy

Key facts at a glance

LOINC
62898-2
Short code
ALP
Synonyms
Alkaline phosphatase proto
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or plain red top tube
Units
not specified
Ref low
40
Ref high
129
Critical range
— – 500 not specified
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
phenx
CPT
84075
SNOMED
27084006
Specimen volume
1.0-2.0 mL serum minimum
Stability
Room temperature: 7 days; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 30 days. Avoid repeated freeze-thaw cycles.
Hemolysis max
50
Lipemia max
100
Icterus max
20
TAT
1–24 hours
Order
routine

What is this test?

The alkaline phosphatase (ALP) test measures the amount of this enzyme in your blood. Alkaline phosphatase is produced by various tissues in your body, with the highest concentrations in the liver, bile ducts, and bones. This test is part of a larger group of blood tests called liver function tests or a comprehensive metabolic panel.

Why is this test performed?

Your doctor may order an ALP test to: check for liver diseases such as hepatitis or cirrhosis; detect bone disorders including bone cancer, Paget's disease, or osteomalacia; identify blockages in the bile ducts; monitor the effectiveness of treatment for liver or bone conditions; or evaluate unexplained symptoms like jaundice, abdominal pain, or bone pain.

How to prepare for the test

You may need to fast (not eat or drink anything except water) for 8-12 hours before the test. Inform your doctor about all medications you are taking, as some drugs can affect ALP levels. These include certain antibiotics, birth control pills, and medications for seizures. Avoid alcohol before the test as it can affect liver enzyme levels.

What to expect during the test

A healthcare professional will draw a small blood sample from a vein in your arm. The procedure takes only a few minutes. You may feel a brief sting or pinch when the needle is inserted. The blood sample will be sent to a laboratory for analysis.

Understanding your results

Normal ALP levels vary based on age, sex, and blood type. Generally, adult normal ranges are 20-140 IU/L (international units per liter), though reference ranges differ between laboratories. Your doctor will interpret your results alongside other liver tests and your overall clinical picture.

Reference range

40-129 U/Lnot specified

Specimen: serum

No special preparation or fasting required

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings3

Frequently asked questions

Does a high ALP level always mean I have a serious disease?
Not necessarily. ALP levels can be elevated due to many factors including recent bone growth (common in children and adolescents), healing fractures, pregnancy (especially in the third trimester), or eating a fatty meal. Your doctor will consider these factors and run additional tests to determine the cause.
Can I take my medications before the ALP test?
You should inform your doctor about all medications you are taking. Some medications can affect ALP results. Do not stop taking prescribed medications unless your doctor specifically instructs you to do so.
How long does it take to get results?
Results are typically available within 1-2 days, though this may vary depending on the laboratory. Your healthcare provider will contact you with the results or discuss them at your follow-up appointment.
Do I need to do anything after the test?
After the blood draw, you can resume your normal activities immediately. If you fasted for the test, you may want to bring a snack to eat afterward. There are no special restrictions following the test.
What is the difference between ALP and other liver enzymes?
While ALT and AST are more specific to liver cell damage, ALP is primarily associated with bile duct function and bone metabolism. Elevated ALP with normal ALT/AST suggests a bile duct problem or bone disorder rather than liver cell injury. Your doctor uses all these tests together to understand your liver and bone health.
  1. 1
    MedlinePlus - Alkaline PhosphataseSource
  2. 2
    Mayo Clinic - Alkaline Phosphatase TestSource
  3. 3
    NIH - PhenX ToolkitSource

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.

Medical Disclaimer

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