What Is Serum Alkaline Phosphatase?

Serum alkaline phosphatase (ALP) belongs to the class of phosphomonoester hydrolases—a group of relatively specific phosphatases. It is normally distributed widely in human tissues and body fluids; the majority is produced by bone cells, while a small portion originates from the liver and is excreted into the intestine via bile. ALP activity is primarily measured using colorimetric or continuous monitoring (kinetic) assays. Elevated serum ALP levels may occur in conditions such as cirrhosis, hepatocellular carcinoma, or chronic renal insufficiency.