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Blood alkaline phosphatase.

 
Author: Alexey Portnov, family doctor
Date created: 03.03.2011
Last reviewed: 27.10.2025

Alkaline phosphatase is widely distributed in human tissues, especially in the intestinal mucosa, osteoblasts, walls of the bile ducts of the liver, placenta and lactating mammary gland. It catalyzes the splitting off of phosphoric acid from its organic compounds; its name is due to the fact that the optimal pH of this enzyme is 8.6-10.1. The enzyme is located on the cell membrane and is involved in the transport of phosphorus. For diagnostic purposes, the activity of the bone and liver forms of alkaline phosphatase is most often determined.

Reference values (norm) of alkaline phosphatase activity in serum (reaction with phenyl phosphate)

Age

Total, IU/L

Bone,%

Newborns

35-106

1 month

71-213

85

3 years

71-142

85

10 years

106-213

85

Adults up to 31 years old

39-92

60

Adults over 31 years old

39-117

40

Bone alkaline phosphatase is produced by osteoblasts, large mononuclear cells that lie on the surface of the bone matrix in areas of intense bone formation. Apparently, due to the extracellular location of the enzyme during calcification, a direct link can be traced between bone disease and enzyme activity in the blood serum.

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