Alkaline Phosphatase (ALP) Blood Test
The alkaline phosphatase (ALP) blood test measures the level of an enzyme found in your liver, bones, intestines, and other tissues. Doctors use this test to help evaluate liver function, bone health, and to investigate symptoms or monitor certain medical conditions as part of your routine care.
{"ALP is an enzyme that helps detect liver and bone disorders","Higher-than-normal levels may indicate liver disease, bone disease, or other conditions","The test is often part of a routine blood panel called a comprehensive metabolic panel (CMP)","Normal levels vary by age, gender, and blood type","Your doctor will interpret results based on your overall health and other test results"}
Key facts at a glance
- LOINC
- 6768-6
- Short code
- ALP
- Synonyms
- ALP SerPl-cCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST/gel tube) 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
- 0–120 years
- Method
- Enzymatic spectrophotometric assay using p-nitrophenyl phosphate (pNPP) as substrate with measurement of product formation at 405 nm
- CPT
- 84075
- SNOMED
- 27550007
- Specimen volume
- 1.0-2.0 mL serum minimum
- Stability
- Room temperature: 7 days; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 40
- TAT
- 1–24 hours
- Order
- routine
What is the Alkaline Phosphatase Test?
The Alkaline Phosphatase (ALP) test is a blood test that measures the amount of ALP enzyme in your bloodstream. ALP is produced by various tissues in your body, including the liver, bones, intestines, and kidneys. This test is commonly performed as part of a routine health checkup or when doctors suspect certain medical conditions.
Why is this Test Performed?
Doctors order the ALP test to help diagnose and monitor conditions affecting the liver and bones. It can detect liver damage, bile duct obstruction, bone disorders such as Paget's disease or osteomalacia, and certain cancers. The test is also useful for monitoring the effectiveness of treatments for these conditions.
How is the Test Done?
A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The sample is then sent to a laboratory for analysis. You do not need to fast before this test unless your doctor instructs otherwise. The procedure only takes a few minutes and is generally safe with minimal risks, such as slight bruising or soreness at the injection site.
Understanding Your Results
Normal ALP levels vary depending on age, sex, and blood type. Generally, adult normal ranges are between 20 to 140 U/L (units per liter), but values outside this range do not always indicate a problem. Your doctor will consider your complete medical history and other test results when interpreting your ALP levels. Slightly elevated levels may be normal for children and pregnant women due to bone growth and placental production of ALP.
Reference range
44-147 U/Lnot specified
No special preparation needed
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated ALP levels can indicate liver diseases such as hepatitis, cirrhosis, or bile duct obstruction. They may also signal bone disorders including Paget's disease, osteomalacia, or bone metastases. Certain medications, heavy alcohol use, and heart failure can also raise ALP levels. Low ALP levels are less common but may occur in malnutrition, zinc deficiency, or certain genetic disorders. Since ALP alone cannot diagnose a specific condition, doctors typically order additional tests (such as GGT or ALT) to determine the exact cause of abnormal levels.
Frequently asked questions
Do I need to fast before the ALP test?
What does a high ALP level mean?
Can a high ALP level mean cancer?
Is the ALP test dangerous?
How long does it take to get results?
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 16, 2026. · Read our editorial policy