| Subject | Contents |
| Definition | A test that measures the amount of the enzyme ALP (alkaline phosphatase) in serum. |
| Alternative Names | Alkaline phosphatase |
| How the test is performed | Blood is drawn from a vein ( venipuncture ) or a capillary sample is obtained from a 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 | 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. |
| How the test will feel | |
| Why the test is performed | Alkaline phosphatase is an enzyme in all tissues. Tissues with particularly high concentrations include liver, bile ducts, placenta and bone. Since damaged or diseased tissue releases enzymes into the blood, serum ALP measurements can be abnormal in many conditions, including bone disease and 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. There are multiple varieties of ALP, called isoenzymes, which have 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. To differentiate the location of damaged or diseased tissue in the body, ALP isoenzymes must be done. |
| Normal Values | The normal range is 44 to 147 IU/L. Note: IU/L = international units per liter Normal values may vary slightly from laboratory to laboratory. They also can vary with age and gender. |
| What abnormal results mean | Greater-than-normal ALP levels may indicate:anemiabiliary obstructionbone disease healing fracturehepatitishyperparathyroidismleukemialiver diseasesosteoblastic bone cancersosteomalaciaPaget's diseaserickets Lower-than-normal ALP levels (hypophosphatasemia) may indicate: malnutritionprotein deficiency Additional conditions under which the test may be performed:alcoholic liver disease (hepatitis/cirrhosis)alcoholismbiliary stricturegiant cell (temporal, cranial) arteritismultiple endocrine neoplasia (MEN) IIrenal cell carcinoma |
| What the risks are | |
| Special considerations | The ALP levels vary with age and gender. It is normal for young children experiencing rapid growth and for pregnant women to have high levels of ALP. |
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