DefinitionAlkaline phosphatase (ALP) is a protein found in all body tissues. Tissues with particularly high amounts of ALP include the liver, bile ducts, and bone.A blood test can be done to measure the level of ALP.See also: ALP isoenzyme test
Alternative NamesAlkaline phosphatase
How the test is performedA blood sample is needed. For information on how this is done, see: Venipuncture
How to prepare for the testYou should not to eat or drink anything for 6 hours before the test, unless otherwise instructed by your doctor.Many drugs affect the level of alkaline phosphatase in the blood. Your health care provider may tell you to stop taking certain drugs before the test. Never stop taking any medicine without first talking to your doctor. Drugs that may affect the ALP level may include:AllopurinolAntibioticsBirth control pillsCertain diabetes medicinesChlorpromazineCortisoneMale hormonesMethyldopaNarcotic pain medicinesNonsteroidal anti-inflammatory drugs (NSAIDs), used for arthritis and pain)PropranololTranquilizersTricyclic antidepressants
How the test will feelWhen 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 performedThis test is done to diagnose liver or bone disease, or to see if treatments for those diseases are working. It may be included as part of a routine liver function test.
Normal ValuesThe normal range is 44 to 147 IU/L (international units per liter).Normal values may vary slightly from laboratory to laboratory. They also can vary with age and gender. High levels of ALP are normally seen in children undergoing growth spurts and in pregnant women.The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What abnormal results meanHigher-than-normal ALP levels may be due to:Biliary obstructionBone diseaseEating a fatty meal if you have blood type O or BHealing fractureHepatitisHyperparathyroidismLeukemiaLiver diseaseLymphomaOsteoblastic bone tumorsOsteomalaciaPaget's diseaseRicketsSarcoidosisLower-than-normal ALP levels (hypophosphatasemia) may be due to:MalnutritionProtein deficiencyWilson's diseaseAdditional conditions under which the test may be performed:Alcoholic liver disease (hepatitis/cirrhosis)AlcoholismBiliary strictureGallstonesGiant cell (temporal, cranial) arteritisMultiple endocrine neoplasia (MEN) IIPancreatitisRenal cell carcinoma
ReferencesBerk PD, Korenblat KM. Approach to the patient with jaundice or abnormal liver test results. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 150.Pratt DS. Liver chemistry and function tests. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 73.