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Alkaline phosphatase (ALP) is an enzyme in your blood that comes mainly from your liver, your bile ducts and your bones. A high level can point to a problem with your liver or your bones, and a low level can point to, among other things, a shortage of zinc or protein.[1]
On this page you can read what alkaline phosphatase is, what the guidelines say about a value that is too low or too high, what affects your value and which other values are best looked at alongside it.
Also known as: ALP, ALK PHOS, Alkp. At the lab: AP.
ALP is an enzyme. That is a protein that makes certain chemical reactions in your body happen faster.[1]
ALP is found in all the tissues of your body. There is more of it in your liver, your bile ducts and your bones.[1]
Each part of your body makes its own type of ALP. The standard test measures how much ALP is in your blood, but not which type.[1]
An abnormal level can be a sign of many kinds of conditions. Think of a liver condition, a bone condition or a long-term kidney condition.[1]
A doctor often requests the test as part of a routine check-up, together with other blood tests. Liver tests are often among them. They show how well your liver is working.[1]
The test can also be useful if you have symptoms that fit with your liver or your bones. Think of tiredness, yellow skin and yellow eyes, itching or pain in your bones.[1]
You can have a higher level without a condition that needs care. Your doctor looks at your symptoms, your medical history and your other results.[1]
The lab BioProfile works with, Labplusarts, uses a reference range of 0 to 98 u/l for ALP. The lab calls a level between those limits normal.[2]
| Value | What it can mean | Who it is for |
|---|---|---|
| 0 to 98 u/l[2] | The lab calls a value between these limits normal | As the lab reports it, without a separate group |
The Labplusarts laboratory's reference value for alkaline phosphatase (AP), for the test at this lab.[2]
A low level is less common. It can point to a shortage of zinc or protein, to malnutrition or to a certain type of anaemia. A thyroid condition or a rare inherited condition of the bones and teeth can also be behind it.[1]
A high level can point to a problem with your liver or your bones. If your liver tests are high too, the ALP most likely comes from your liver, for example because of a blockage in the bile ducts or inflammation of the liver. If your liver tests are normal, it may be a bone condition. A moderately high level can fit with many kinds of conditions, including a heart condition.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
If you are pregnant, your ALP can be higher than normal.[1]
Children and teenagers can have a high ALP, because their bones are still growing.[1]
The contraceptive pill and certain medicines can lower your ALP. Other medicines can raise it. Tell your doctor what you take, and do not stop taking anything without talking to them first.[1]
A fatty meal before the test can raise your ALP slightly. You are often asked not to eat or drink for a few hours before your blood is taken.[1]
ALP is included in BioProfile 77, 98, 121 and 150.[3]
The BioProfile editorial team wrote this page on 8 October 2026 from the sources below, which we read on 8 October 2026. Every number on this page appears in one of those sources, with the number of that source next to it. An expert will still review this page; after that review, the expert's name and the date of the review will appear at the top. This page offers explanation, not a diagnosis. Discuss an abnormal level with your GP.
