An alkaline phosphatase (ALP) test measures the amount
enzyme ALP in the blood. ALP is made mostly in the
liver and in bone with some made in the
kidneys . It also is made by the
placenta of a pregnant woman.
makes more ALP than the other organs or the bones. Some conditions cause large
amounts of ALP in the blood. These conditions include rapid bone growth (during
puberty), bone disease (such as
Paget's disease or cancer that has spread to the bones), a disease that affects how much
calcium is in the blood (hyperparathyroidism), vitamin D deficiency, or damaged liver cells.
If the ALP level is high, more tests may be done to find the
cause. The amounts of different types of ALP in the blood may be measured and used to determine whether a high level is from the liver or bones. This is called an alkaline phosphatase isoenzymes test.
Why It Is Done
A test for alkaline phosphatase (ALP) is
- Check for liver disease or damage to the liver.
Symptoms of liver disease can include
jaundice, belly pain, nausea, and vomiting. An ALP
test may also be used to check the liver when medicines that can damage the
liver are taken.
- Check bone problems (sometimes found on
X-rays), such as
rickets, bone tumors, Paget's disease,
or too much of the hormone that controls bone growth (parathyroid hormone). The ALP level can be used to check how well treatment for
Paget's disease or a vitamin D deficiency is working.
How To Prepare
An alkaline phosphatase test is often
done at the same time as a routine blood test. You do not need to do anything
before having a routine blood test.
If you are having a follow-up
ALP test, you may be asked to not eat or drink for 10 hours before the test.
The ALP level generally goes up after eating, especially after eating fatty
Many medicines may change the results of this test. Be sure
to tell your doctor about all the
nonprescription and prescription medicines you
Talk to your doctor about any concerns you have regarding the
need for the test, its risks, how it will be done, or what the results will
mean. To help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
The health professional drawing your
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure to the site and then a bandage.