This test measures the amount of alkaline phosphatase in blood. Alkaline phosphatase is an enzyme found throughout the body. Like all enzymes, it is needed, in small amounts, to trigger specific chemical reactions. When it is present in large amounts, it may signify bone or liver disease or a tumor. Growing bones need alkaline phosphatase. Any condition of bone growth will cause alkaline phosphatase levels to rise. It rises in diseases, such a bone cancer, Paget's disease, or rickets. Some tumors, however, start production of the same kind of alkaline phosphatase produced by the placenta. These tumors are called germ cell tumors and include testicular cancer and certain brain tumors. It is a part of Liver Function Test. It is always advisable to go for complete profile, as level of each test in profile are considered while making decision on diagnosis as well as monitoring the treatment.