ALP
Alternative names:
alkaline phosphatase; hypophosphatasia
How the test is performed:
Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test:
Fast for 6 hours.
The 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.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
How the test will feel:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed:
This test helps determine the location of damaged or diseased tissue in the body.
Alkaline phosphatase is an enzyme in all tissues. Tissues with particularly high concentrations include liver, bile ducts, and bone cells. There are multiple varieties of ALP, called isoenzymes, with slightly different structures. Different types of isoenzymes are in different tissues (for example, liver and bone ALP isoenzymes have different structures and can be quantified separately in the laboratory). Since damaged or diseased tissue releases enzymes into the blood, serum ALP measurements can differentiate bone disease from liver disease. However, serum ALP is also increased in some normal circumstances (for example, during normal bone growth) or in response to a variety of drugs.
|
