ALP

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ALP

Definition:

This is a blood test that measures the amount of the enzyme ALP (alkaline phosphatase).

Alternative Names:
Alkaline phosphatase
How the test is performed:

Blood is drawn from a vein or from a capillary on the heel, finger, toe, or earlobe. The laboratory centrifuges the blood to separate the serum from the cells. The ALP test is done on the serum.

How to prepare for the test:

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Fast for 6 hours.

Your health care provider may advise you to discontinue drugs that may affect the test, such as:

antibiotics
narcotics
methyldopa
propranolol
cortisone
allopurinol
tricyclic antidepressants
chlorpromazine
oral contraceptives (birth control pills)
anti-inflammatory analgesics
androgens
tranquilizers
some antiarthritic drugs
oral antidiabetic drugs

Why the test is performed:

Alkaline phosphatase is an enzyme found in all tissues. Tissues with particularly high concentrations of ALP include the liver, bile ducts, placenta, and bone.

Damaged or diseased tissue releases enzymes into the blood, so serum ALP measurements can be abnormal in many conditions, including bone disease and liver disease. Serum ALP is also increased in some normal circumstances (for example, during normal bone growth) or in response to a variety of drugs.

There are multiple varieties of ALP, called isoenzymes. Different types of isoenzymes, each with different structures, are found in different tissues (for example, liver and bone ALP isoenzymes have different structures) and can be quantified separately in the laboratory. To differentiate the location of damaged or diseased tissue in the body, ALP isoenzyme testing must be done.