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Alkaline Phosphatase Test

An alkaline phosphatase (ALP) test measures the amount of ALP enzyme in your blood. Abnormal levels may signal liver, bone, or other health conditions, but the test alone cannot identify the source.

What this test measures

The alkaline phosphatase (ALP) test measures the amount of ALP enzyme in your blood. ALP is found in all body tissues, with higher amounts in the liver, bile ducts, and bones.

What your results mean

Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.

Higher-than-normal results

High ALP levels may be a sign of a liver problem (such as bile duct blockages, cirrhosis, hepatitis, or mononucleosis) or a bone disorder (like Paget's disease). Moderately high levels may also occur with Hodgkin lymphoma, heart failure, or certain infections.

Lower-than-normal results

Low ALP levels may be a sign of zinc deficiency, protein deficiency, malnutrition, pernicious anemia, thyroid disease, Wilson disease, or hypophosphatasia (a rare genetic disease affecting bones and teeth).

Frequently asked questions

What is an alkaline phosphatase test?

It measures the amount of ALP enzyme in your blood. ALP is found in many tissues, especially the liver, bile ducts, and bones.

Why might I need this test?

It is often used to screen for or help diagnose liver or bone diseases, and may also help monitor other health conditions.

What do high ALP levels mean?

High levels may indicate a liver problem (like bile duct blockage, cirrhosis, or hepatitis) or a bone disorder (like Paget's disease). Moderately high levels can also occur with other conditions.

What do low ALP levels mean?

Low levels are less common and may be due to zinc or protein deficiency, malnutrition, pernicious anemia, thyroid disease, Wilson disease, or hypophosphatasia.

Can this test alone diagnose a condition?

No. The test alone cannot identify the source of ALP. Your provider will consider your symptoms, medical history, and other test results to make a diagnosis.

Related lab tests

Sources

Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.