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Published on: April 12, 2019
Serum alkaline phosphatase in hypophosphatasia
The Journal of Clinical Investigation
|October 1, 1971
Summary
In hypophosphatasia, intestinal alkaline phosphatase is the main enzyme component in serum after consuming long-chain fats. This finding highlights the role of intestinal alkaline phosphatase in this genetic disorder.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Background:
- Serum alkaline phosphatase (ALP) activity originates from multiple tissues, including bone, liver, and intestine.
- Hypophosphatasia is a rare genetic disorder affecting bone mineralization, often associated with altered ALP levels.
Purpose of the Study:
- To investigate the source and behavior of serum alkaline phosphatase in individuals with hypophosphatasia.
- To determine the impact of fat digestion on serum intestinal alkaline phosphatase levels in hypophosphatasia.
Main Methods:
- Analysis of serum alkaline phosphatase isoenzymes in two siblings with hypophosphatasia.
- Administration of long-chain and medium-chain triglycerides to assess changes in serum ALP activity.
- Enzyme inhibition studies using l-phenylalanine to identify the origin of ALP.
- Starch block electrophoresis to separate and visualize different ALP components.
Main Results:
- Serum ALP in hypophosphatasia patients was predominantly of intestinal origin after long-chain triglyceride intake, confirmed by l-phenylalanine inhibition.
- Starch block electrophoresis revealed additional l-phenylalanine-sensitive ALP bands beyond the main intestinal isoenzyme.
- Medium-chain triglycerides, absorbed via the portal system, did not significantly increase intestinal ALP activity.
Conclusions:
- Serum intestinal alkaline phosphatase levels increase normally following long-chain fat ingestion in hypophosphatasia.
- Intestinal alkaline phosphatase can be the primary contributor to total serum ALP activity in hypophosphatasia patients.
- These findings contribute to understanding the metabolic profile and diagnostic markers in hypophosphatasia.
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