Alkaline phosphataseALP
An enzyme from the liver and bones, read as part of a liver panel.
Alkaline phosphatase (ALP) is an enzyme found mainly in the liver and bones, with smaller amounts elsewhere. Levels rise when there is activity or obstruction in the bile ducts of the liver, or increased bone turnover.
It matters because ALP helps tell different kinds of liver issue apart from the other enzymes, and because it also reflects bone activity — which is why it can be naturally higher in growing adolescents and in pregnancy. It contributes to blood-based biological-age scoring.
In practice, ALP is interpreted alongside ALT and the rest of the liver panel; whether a raised level points to liver or bone is usually clarified by the pattern of the other markers.
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Written and reviewed by Mathew Beale, MSc Biotechnology, University of Reading.
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