What is an alkaline phosphatase test?
An alkaline phosphatase (ALP) test measures the amount of ALP in your blood. ALP is an enzyme found throughout the body, but it is mostly found in the liver, bones, kidneys, and digestive system. When the liver is damaged, ALP may leak into the bloodstream. High levels of ALP can indicate liver disease or bone disorders.
Other names: ALP, ALK, PHOS, Alkp, ALK PHOS
What is it used for?
An alkaline phosphatase test is used to detect diseases of the liver or bones.
Why do I need an alkaline phosphatase test?
Your health care provider may have ordered an alkaline phosphatase test as part of a routine checkup or if you have symptoms of liver damage or a bone disorder. Symptoms of liver disease include:
- Nausea and vomiting
- Weight loss
- Jaundice, a condition that causes your skin and eyes to turn yellow
- Swelling and/or pain in your abdomen
- Dark-colored urine and/or light-colored stool
- Frequent Itching
Symptoms of bone disorders include:
- Pain in the bones and/or joints
- Enlarged and/or abnormally shaped bones
- Increased frequency of bone fractures
What happens during an alkaline phosphatase test?
An alkaline phosphatase test is a type of blood test. During the test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
You don’t need any special preparations for an alkaline phosphatase test. If your health care provider has ordered other blood tests, you may need to fast (not eat or drink) for several hours before the test. Your health care provider will let you know if there are any special instructions to follow.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
High alkaline phosphatase levels may mean there is damage to your liver or that you have a type of bone disorder. Liver damage creates a different type of ALP than bone disorders do. If the test results show high alkaline phosphatase levels, your health care provider may order additional tests to find out where the extra ALP is coming from. High alkaline phosphatase levels in the liver can indicate:
- A blockage in the bile duct
- Mononucleosis, which can sometimes cause swelling in the liver
There are several other types of blood tests that check your liver function. These include bilirubin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) tests. If these results are normal and your alkaline phosphatase levels are high, it may mean the problem is not in your liver. Instead, it can indicate a bone disorder, such as Paget’s Disease of Bone, a condition that causes your bones to become abnormally large, weak, and prone to fractures.
Moderately high levels of alkaline phosphatase may indicate conditions such as Hodgkin lymphoma, heart failure, or a bacterial infection.
Low levels of alkaline phosphatase may indicate hypophosphatasia, a rare genetic disease that affects bones and teeth. Low levels may also be due to a deficiency of zinc or malnutrition. To learn what your results mean, talk to your health care provider.
Is there anything else I need to know about alkaline phosphatase test?
ALP levels can vary for different groups. Pregnancy can cause higher than normal ALP levels. Children and teens may have high levels of ALP because their bones are growing. Certain drugs, such as birth control pills, may lower ALP levels, while other medicines can cause the levels to increase.