Alkaline Phosphatase (ALP) Blood Test
A blood test that measures the amount of alkaline phosphatase in your blood, an enzyme produced mainly by the liver and bones that helps doctors evaluate liver function and bone health.
{"ALP is an enzyme found mainly in the liver and bones","High levels may indicate liver disease, bone disorders, or bile duct problems","Low levels are less common but may indicate malnutrition or zinc deficiency","The test is often part of routine liver function panels","Results are interpreted together with other liver enzymes for accurate diagnosis"}
Key facts at a glance
- LOINC
- 32135-6
- Short code
- ALP
- Synonyms
- ALP Liver SerPl HS-cCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST/gold top) or plain red top tube
- Units
- not specified
- Ref low
- 40
- Ref high
- 129
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- heat-stability
- CPT
- 84075
- SNOMED
- 271253001
- Specimen volume
- 0.5-1.0 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
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–24 hours
- Order
- routine
What is this test?
The Alkaline Phosphatase (ALP) test measures the amount of this enzyme in your blood. ALP is produced primarily by the liver and bones, with smaller amounts coming from the intestines and kidneys. This test is commonly included in routine blood work to assess liver function and bone health.
Why is it performed?
Your doctor may order an ALP test to: evaluate liver function and check for liver diseases such as hepatitis or cirrhosis; investigate bile duct blockages or gallstones; diagnose bone disorders including bone cancer, Paget's disease, or osteoporosis; monitor the effectiveness of treatments for liver or bone conditions; or as part of a comprehensive metabolic panel during routine check-ups.
How is the test performed?
A healthcare professional will draw a small blood sample from a vein in your arm. The sample is then sent to a laboratory for analysis. You do not need to fast before this test unless specifically instructed by your doctor. The procedure takes only a few minutes and carries minimal risks, such as slight bruising or soreness at the needle site.
Understanding your results
Normal ALP levels vary by age, sex, and blood type. Generally, adult normal ranges are between 20 to 140 IU/L, though laboratory reference ranges may differ. Elevated ALP may indicate liver disease, bile duct obstruction, gallstones, bone disorders, or certain medications. Low ALP levels are less common but can result from malnutrition, zinc deficiency, hypothyroidism, or certain genetic conditions. Your doctor will interpret your results in context with other tests and your overall health condition.
Reference range
40-129 U/Lnot specified
No fasting or special preparation required
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated ALP is commonly associated with liver conditions such as hepatitis, cirrhosis, or liver tumors; bile duct obstruction from gallstones or strictures; bone diseases including Paget's disease, osteomalacia, or bone metastases; and pregnancy (due to placental ALP). Isolated ALP elevation requires additional testing, such as GGT or ALT/AST, to determine whether the source is liver or bone. Low ALP may indicate malnutrition, zinc deficiency, hypothyroidism, or rare genetic disorders. This test helps doctors differentiate between liver and bone pathology when combined with clinical symptoms and other laboratory findings.
Frequently asked questions
Do I need to fast before the ALP test?
Can medications affect ALP levels?
What happens if my ALP is high?
Is the ALP test dangerous?
How often should ALP be tested?
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