All You Need to Know about Liver Function Tests

Cholestasis tests

These tests include the classic bilirubin test and another enzyme known as alkaline phosphatase. Bilirubin is the result of the catabolism of hemoglobin and other sources of protein heme. It is a water-insoluble substance transported in the blood bound to a protein known as albumin. The liver should conjugate bilirubin to make it water-soluble, and only then it is included in the bile, collected in the gallbladder, and eliminated in the gut. When the liver cannot process bilirubin, this substance stays in the blood as conjugated or unconjugated bilirubin.

On the other hand, alkaline phosphatase is a substance found in the bile canaliculus. But it is also found in the placenta, the intestines, and the bones. Their levels tend to be higher in adolescents during growth spurts. Additionally, there’s an enzyme known as gamma-glutamyltransferase or GGT. This one is located on cell membranes. It is also found in other tissues but not in the bone, making it a great candidate to increase the specificity of alkaline phosphatase.