Veterinary Clinical Biochemistry and Laboratory Diagnosis

INTRODUCTION

• Bilirubin is an orange coloured bile pigment produced by the breakdown of heme to biliverdin and further reduction of biliverdin.
• It normally circulates in plasma and is taken up by liver cells and conjugated to form bilirubin diglucuronide; the water-soluble pigment excreted in the bile.
• Failure of the liver cells to excrete bile, or obstruction of the bile ducts, can cause an increased amount of bilirubin in the body fluids. And thus it leads to obstructive or regurgitation jaundice.
• Another type of jaundice results from excessive destruction of erythrocytes (hemolytic or retention jaundice).
• The more rapid the destruction of red blood cells and the degradation of hemoglobin, the greater the amount of bilirubin in the body fluids.
• Most bilirubin is excreted in the feces. A small amount is excreted in the urine as urobilinogen.