High or Low What Your Alkaline Phosphatase Levels Mean for You

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What is an Alkaline Phosphatase Test?

An alkaline phosphatase (ALP) test measures the level of ALP in your blood. ALP is an enzyme that exists in many tissues throughout your body. Each tissue produces a specific type of ALP. The majority of ALP is found in your liver, bones, kidneys, and digestive system.

Abnormal ALP levels in your blood can indicate various health issues, including liver disease, bone disorders, and chronic kidney disease. However, an ALP test alone cannot determine the exact source of the ALP, so additional tests are typically required for an accurate diagnosis.


Other names for this test include: ALP, ALK, PHOS, AlKP, and ALK PHOS.


What is it used for?

An alkaline phosphatase test is primarily used to screen for or help diagnose liver or bone diseases. It can also be used to diagnose or monitor other health conditions.


Why do I need an alkaline phosphatase test?

Your healthcare provider might order an ALP test as part of a routine checkup. Many conditions can affect ALP levels, so it is often performed alongside other blood tests, such as a comprehensive metabolic panel (CMP) or liver function tests, to assess liver health.

An ALP test may also be ordered if you exhibit symptoms of liver damage or a bone disorder. 


Symptoms of liver disease include:


  • Nausea and vomiting
  • Loss of appetite
  • Fatigue
  • Weakness
  • Jaundice (yellowing of the skin and eyes)
  • Swelling or pain in the abdomen
  • Swelling in the ankles and legs
  • Dark urine and/or light-colored stool
  • Frequent itching

Symptoms of bone disorders include:


  • Bone pain
  • Joint inflammation and arthritis
  • Abnormally shaped or oversized bones
  • Frequent bone fractures

What happens during an alkaline phosphatase test?

An ALP test is a simple blood test. A medical professional will use a small needle to take a blood sample from a vein in your arm. Once the needle is in place, a small quantity of blood will be drawn into a test tube or vial. You may experience a slight sting when the needle goes in or comes out. The entire procedure typically takes under five minutes.

Should I Take Any Steps to Get Ready for the Test?

Preparation for an ALP test depends on the lab conducting the test. Some labs may require you to fast (not eat or drink) for 6 to 12 hours before the test. Since ALP tests are often done with other blood tests that may require fasting, your provider will inform you of any specific instructions.


Are there any risks to the test?

Blood tests carry minimal risk. You might experience slight pain or bruising where the needle was inserted, but these symptoms usually resolve quickly.


What do the results mean?

High ALP levels can indicate a liver problem or bone disorder. Liver issues and bone disorders produce different types of ALP, but test results alone cannot specify which type is elevated.

If your ALP levels are high, your healthcare provider might order additional tests to determine the cause. These tests may include:

ALP Isoenzyme Test: Identifies the specific source of ALP, though not widely available.
Liver Function Tests: High results suggest a liver issue.

High ALP levels from the liver may indicate:


  • Bile duct blockages
  • Cirrhosis
  • Hepatitis
  • Mononucleosis (which can cause liver swelling)

If ALP levels are high but liver tests are normal, the issue may be a bone disorder, such as Paget's disease, which causes bones to become unusually large and weak.

Moderately high ALP levels might suggest various conditions, including Hodgkin lymphoma, heart failure, or certain infections.

It is possible to have elevated ALP levels without needing treatment. Your provider will consider your symptoms, medical history, and other test results for a diagnosis.

Low ALP levels are rare but may indicate a zinc deficiency, malnutrition, pernicious anemia, thyroid disease, Wilson disease, or hypophosphatasia (a rare genetic disorder affecting bones and teeth).


Is there anything else I need to know about the alkaline phosphatase test?

Many factors can influence ALP levels. Pregnancy can increase ALP levels. Children and teenagers may have higher ALP levels due to bone growth. Birth control pills and certain medications can lower ALP levels, while other medications can increase them. Even consuming a fatty meal before the test can slightly elevate ALP levels.

For a clear understanding of your results, discuss them with your healthcare provider.