Alkaline phosphatase is an enzyme primarily found in a number of organs and tissues. Although mostly inactive in blood, alkaline phosphatase can be found in the bloodstream as it's released from organs and tissues. Laboratory analysis of blood samples can detect abnormalities in alkaline phosphatase levels found in the blood. As a result, changes in blood alkaline phosphatase can be an indicator of certain health conditions, including liver disease.
Alkaline Phosphatase
Alkaline phosphatase is an enzyme primarily found in the liver and bone. The primary role of alkaline phosphatase is to cleave phosphate groups off biological molecules, thereby regulating or altering their function. Other tissues including kidneys, intestines and the placenta contain smaller amounts of alkaline phosphatase. Different isozymes or subtypes of alkaline phosphatase are found in various tissues.
Liver and Alkaline Phosphatase
The mucosal cells of the biliary tract are responsible for production of alkaline phosphatase inside the liver. The primary isozyme of alkaline phosphatase found in the liver is ALP-1. Normally, alkaline phosphatase follows bile as it flows from the liver into the biliary tract and gallbladder. In cases of liver disease or biliary obstruction, excess alkaline phosphatase is released into the bloodstream, according to drkaslow.com.
Alkaline Phosphatase Testing
Alkaline phosphatase levels can be obtained from routine blood samples. Because alkaline phosphatase levels spike after eating, patients may be asked to restrict food intake before the test. Normal adult alkaline phosphate levels range between 30 and 126 units per liter. Children and pregnant women normally have even higher levels due to rapid bone growth or the presence of a placenta, says cigna.com.
Significance
Because alkaline phosphatase is primarily found in bone and liver tissue, test abnormalities may be an important indicator of bone or liver disease. Increased alkaline phosphatase levels may indicate the presence of liver disease or biliary obstruction. In addition, abnormalities may also be a result of conditions that cause bone breakdown. Low alkaline phosphatase levels may be indicative of malnutrition. Because many other conditions may cause changes in alkaline phosphatase levels, lab tests alone cannot be used to definitively determine the presence of liver disease, says cigna.com.
Other Factors Affecting Alkaline Phosphatase Levels
Several other factors can affect alkaline phosphatase levels. Medications and alcohol that may cause acute injury to the liver may increase alkaline phosphatase levels. Research has also shown that post-menopausal women may also have higher alkaline phosphatase levels, according to cigna.com.
