Alkaline Phosphatase (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 (especially those involving increased bone-building cell activity), and certain gastrointestinal diseases. Mild increases in ALP can also occur with conditions that don't involve the liver or bones. 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.

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.

High alkaline phosphatase (ALP) levels may be a sign of a liver problem or a bone disorder. Liver problems and bone disorders create different types of ALP, but a standard ALP test can't tell which type is high.

Very high ALP levels (often more than four times normal) often point to a blockage in the bile ducts, such as from a gallstone, a tumor, or scarring of the ducts. The level usually drops once the blockage is treated.

Smaller increases (less than two to three times normal) are more typical of liver inflammation (hepatitis) or a side effect of certain medicines.

If alkaline phosphatase levels are high and the results of liver tests are normal, the problem may be a bone disorder, such as Paget's disease of bone, healing fractures, or growing bones in children and teens. This type of disease makes your bones unusually large and weak, which can cause them to break more easily.

If your test results show high ALP levels, your provider may order other tests, such as a GGT, to help figure out whether the source is your liver or your bones.