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Alkaline Phosphatase (ALP)

Published: July 27, 2026Updated: August 25, 2026

Alkaline phosphatase (ALP) is an enzyme found in various tissues throughout the body, with high concentrations in the liver, bones, and bile ducts. It is commonly measured to assess liver function and diagnose conditions affecting these organs.

Quick summary

ALP is an enzyme primarily used to evaluate liver and bone health.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
U/L
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche ALP, Abbott ALP, Siemens ALP
interpretation: {"text":"ALP levels within the range of 44–147 U/L are generally considered normal.","label":"Normal"}; {"text":"Levels above 147 U/L may indicate liver disease, bile duct obstruction, or bone disorders.","label":"Elevated"}

Alkaline phosphatase (ALP) is an enzyme present in multiple body tissues, with significant levels found in the liver, bones, and bile ducts. Elevated ALP levels can indicate liver diseases, such as hepatitis or cirrhosis, or conditions affecting bone metabolism, like Paget's disease.

In clinical practice, ALP is often used alongside other liver function tests to diagnose and monitor liver disorders. It is also a key marker in evaluating bone disorders and certain cancers.

The reference range for ALP is typically between 44–147 U/L. Values above this range may necessitate further diagnostic evaluation to identify the underlying cause.

Frequently asked questions

What causes elevated ALP levels?
Elevated ALP levels can be caused by liver diseases such as hepatitis, cirrhosis, or bile duct obstruction, as well as bone disorders like Paget's disease and certain cancers.
How is an ALP test performed?
An ALP test is performed through a simple blood draw. The sample is then analyzed in a laboratory to measure the enzyme levels.
  1. 1
    Alkaline Phosphatase - Lab Tests OnlineSource
  2. 2
    Alkaline Phosphatase - MedlinePlusSource

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 25, 2026. · Read our editorial policy