Alkaline Phosphatase

An alkaline phosphatase (ALP) test measures the amount of ALP in your blood. ALP is an enzyme, a protein that speeds up certain chemical reactions in your body. ALP is found in all your body tissues, but higher amounts can be found in your liver, bile ducts, and bones.

Each part of your body makes a different type of ALP. Abnormal levels of ALP in your blood may be a sign of a wide range of health conditions, including liver disease, bone disorders, and chronic kidney disease. The amount of ALP released into your blood can be affected by liver damage, conditions that affect bone growth, and certain gastrointestinal diseases.

But an alkaline phosphatase test alone can't identify the source of ALP in your blood, so other tests are usually needed to make a diagnosis.

Why this test is done

Your health care provider may order an alkaline phosphatase test as part of a routine checkup. Many conditions may affect ALP levels, so the test is often done with other blood tests. These other tests can include a comprehensive metabolic panel (CMP) or liver function tests, which check how well your liver is working.

An alkaline phosphatase test may also be ordered if you have symptoms of liver damage or a bone disorder.

Symptoms of liver disease can include:

• Nausea and vomiting
• Lack of appetite
• Fatigue
• Weakness
• Jaundice, a condition that causes your skin and eyes to turn yellow
• Swelling and/or pain in your abdomen (belly)
• Swelling in your ankles and legs
• Dark-colored urine (pee) and/or light-colored stool (poop)
• Frequent itching

Symptoms of bone disorders can include:

• Bone pain
• Inflammation and arthritis in your joints
• Bones that are unusually shaped and/or too large
• Broken bones

How to prepare

Your provider will let you know if there are any special instructions. An ALP test is usually ordered with other blood tests. You usually need to fast (not eat or drink) for several hours before these tests.

You may need to stop taking certain medicines before the test, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to.

Sample type

Blood

Other names for this test

ALP, ALK, PHOS, Alkp, ALK PHOS