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Blood alkaline phosphatase.
Last reviewed: 05.07.2025
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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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