Alkaline phosphatase

alkaline phosphatase /al·ka·line phos·pha·tase/ (ALP) (fos´fah-tas) an enzyme that catalyzes the cleavage of orthophosphate from orthophosphoric monoesters under alkaline conditions. Differing forms of the enzyme occur in normal and malignant tissues. The activity in serum is useful in the clinical diagnosis of many illnesses. Deficient bone enzyme activity, an autosomal recessive trait, causes hypophosphatasia.

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leukocyte alkaline phosphatase  (LAP) the isozyme of alkaline phosphatase occurring in the leukocytes, specifically in the neutrophils; LAP activity is used in the differential diagnosis of neutrophilia, being lowered in chronic myelogenous leukemia but elevated in a variety of other disorders.

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alkaline phosphatase

n.

A phosphatase with an optimum functioning at pH 8.6; it is present throughout the body.

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Alkaline phosphatase

An enzyme found throughout the body, primarily in liver, bone, placenta, and intestine.

Mentioned in: Alkaline Phosphatase Test

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alkaline phosphatase 'Alk phos' Clinical chemistry A 69 kD homodimeric metalloenzyme with broad specificity, which is widely distributed in nature, has an optimal activity at a high–± 10 pH, and occurs in multiple forms–isoenzymes in the liver, intestines, and bone; AP hydrolyzes phosphate esters, yielding alcohol and phosphate; because ↑ total AP indicates either liver or bone disease, additional clinical studies–eg, evaluation of AP isoenzymes, are required to determine the cause of the elevation Physiologic ↑ in AP: During bone growth, infants, children and adolescents-levels are 3-fold > than adults, pregnancy, hepatobiliary disease–eg viral hepatitis, severe biliary obstruction, biliary cirrhosis, intrahepatic cholestasis, Paget's disease of bone, osteomalacia, osteogenic sarcoma, bone metastasis, hyperparathyroidism, infectious mononucleosis, vitamin D deficiency rickets; ↓ in hypoposphatasia, protein deficiency, magnesium deficiency Ref Range AP ranges differ according to method and lab. See Alkaline phosphatase isoenzyme, Immunoperoxidase.