- Last Update On : 2013-10-06
Alkaline phosphatase refers to a family of enzymes that catalyze hydrolysis of phosphate esters at an alkaline pH.ALP is present (in decreasing order of abundance) in placenta, intestine, kidney, bone and liver. In adults, more than 80% of serum ALP activity derives from liver and bone. In late pregnancy, placental ALP is increased. In children and adolescents most serum ALP activity originates in osteoblasts and correlates with the rate of bone growth. The serum half‑life is seven days.
Several caveats must be remembered in interpreting ALP results:
- ALP levels should always be measured after fasting because enzyme levels increase as much as 30 U/L after food ingestion. Patients with blood group O and B who are secretors can have increased ALP levels after eating a fatty meal because of the release of intestinal enzyme.
- African Americans have 10 to 15% higher ALP serum levels than Caucasians.
- In children, ALP is increased up to 3 times th