Doctors test for alkaline phosphatase, or ALP, levels by drawing a patient's blood and ordering a laboratory test, according to Lab Tests Online. The test measures ALP levels in the blood sample.
Alkaline phosphatase is an enzyme found in a number of tissues throughout the body, explains Lab Tests Online. The highest concentrations of ALP are found in bone and liver tissue. The ALP test is often used as part of a routine blood test, such as a liver panel, or as part of a targeted diagnostic panel for specific liver or bone conditions. Tumors, obstructions or other problems can cause these tissues to release increased amounts of ALP into the bloodstream.