Alkaline Phosphatase Isoenzymes and Leukocyte Alkaline Phosphatase Score in Patients with Acute and Chronic Disease: A Brief Review

Aims: To conduct a review of the literature concerning existing methods to detect alkaline phosphatase (ALP) in human serum and to examine the dietary factors that modulate ALP-intestinal isoenzyme (IAP) activity, in light of new findings about its additional functions.
Background: Alkaline phosphatase (ALP) testing is used to detecting liver diseases and bone disorders. When the liver is impaired, damaged hepatocytes release increased amounts of ALP into the blood. If the results of other liver tests, such as for bilirubin, aspartate aminotransferase (AST), and/or alanine aminotransferase (ALT), are high, usually the ALP is usually coming from the liver. If it is not clear from the patient’s signs and symptoms or from the results of other routine tests whether the high ALP originates from is due to liver or bone, then a test for ALP isoenzymes, produced by different types of tissue, may be necessary to distinguish the sources of APL.
There are 4 gene ALP families: 1), intestinal (found on chromosome 2); placental (2); germ cell (3) and non–tissue-specific (4). The tissue nonspecific isoenzyme includes the common serum forms of ALP from bone and liver.
Discussion of Testing Methods: The total ALP activity is typically measured colorimetrically using the p-nitrophenol method. ALP isoenzyme levels can be measured via a method described by the Japanese Society of Clinical Chemistry, in which the ALP isoenzymes are separated electrophoretically with Titan III supporting media. A mouse monoclonal antibody specific to the bone alkaline phosphatase (BAP) is available and, has been adapted to an immunoassay to detection this enzyme.
Conclusion: Isoenzyme testing is crucial before an accurate diagnosis can be made; this option should be considered when the signs and symptoms of certain diseases fail to provide a clear answer that explains clinical or laboratory features in acute or chronic diseases.