Page 12 - Clinical Biochemistry 08PB804

Functions

• Drugs are eliminated in the bile.

• Red blood cells are re-circulated through the bile system.

• Fats are absorbed from intestines into the blood stream only in the presence of bile.

• Fat soluble vitamins, A, D, E, and K, require bile for proper absorption from intestines.
These vitamins are stored in the liver, and are converted to active compounds as the liver
maintains normal physiology (homeostasis).

Bilirubin

• Bilirubin is the main bile pigment that is formed from the breakdown of heme in red blood
cells.

• Serum bilirubin is considered a true test of liver function, as it reflects the liver's ability to
take up, process, and secrete bilirubin into the bile.

• This "free bilirubin", is in a lipid-soluble form that must be made water-soluble to be
excreted.

• The free, or unconjugated, bilirubin is carried by albumin to the liver, where it is converted
or conjugated and made water soluble.

• Once it is conjugated into a water-soluble form, bilirubin can be excreted in the urine.

Jaundice

• Jaundice is the discoloration of body tissues caused by abnormally high levels of bilirubin.

• Bilirubin levels greater than 3 mg/dl usually produce jaundice.

• Once the jaundice is recognized clinically, it is important to determine whether the
increased bilirubin level is prehepatic or posthepatic jaundice.

• A rise in unconjugated bilirubin indicates prehepatic or hepatic jaundice and is treated
medically, whereas a rise in conjugated bilirubin indicates posthepatic jaundice or biliary
obstruction, a condition that may require bile duct surgery or therapeutic endoscopy.

Physiologic jaundice