The alkaline phosphatase test measures the amount of the enzyme ALP in the blood, says WebMD. The test is used to check for liver disease or damage, or to look for bone problems such as rickets, bone tumors, Paget's disease or abnormal bone growth.
The alkaline phosphatase test consists of a simple blood test, and it is often taken at the same time as other routine blood testing. If a follow-up alkaline phosphatase test is required, a patient may be asked to abstain from eating or drinking for 10 hours prior to testing, reports WebMD. Some medications may alter the results of the test, so patients need to let their physician know about any prescription or nonprescription drugs they are taking.