Definition

1. Noun:
   • A reddish-yellow pigment in bile: Bilirubin is an orange-yellow substance formed in the liver as a breakdown product of hemoglobin from old red blood cells. It is a normal component of bile.
   • A clinical indicator: Elevated levels of bilirubin in the bloodstream are responsible for the yellow discoloration of the skin and eyes seen in jaundice.

Usage Examples

• Noun:
  • The blood test showed a high level of bilirubin, indicating a possible liver problem.
  • Bilirubin is excreted from the body in bile and gives feces its characteristic brown color.
  • Newborns often have physiological jaundice due to immature liver function and a temporary rise in bilirubin.

Advanced Usage

• "Conjugated bilirubin" (or direct bilirubin): This form has been processed by the liver and is water-soluble, ready for excretion.
  • A rise in conjugated bilirubin often suggests a blockage in the bile ducts.
• "Unconjugated bilirubin" (or indirect bilirubin): This is the form that has not yet been processed by the liver; it is fat-soluble and bound to proteins in the blood.
  • Hemolytic anemia causes an increase in unconjugated bilirubin.

Variants and Related Words

• Hyperbilirubinemia (n): The medical term for an abnormally high level of bilirubin in the blood.
  • Hyperbilirubinemia is the direct cause of jaundice.
• Bilirubinuria (n): The presence of bilirubin in the urine, which is an abnormal finding.
  • Bilirubinuria is a sign that conjugated bilirubin is leaking into the bloodstream.

Synonyms

• Bile pigment: A general term for coloring substances in bile, including bilirubin.
• Hematoidin (in older or histological contexts): A pigment identical to bilirubin that can be found in tissues after bleeding.

Related Phrases and Terms

• Bilirubin encephalopathy (also known as kernicterus): A rare but serious type of brain damage in infants caused by very high levels of unconjugated bilirubin.
  • Early treatment of severe jaundice is essential to prevent bilirubin encephalopathy.
• Total bilirubin: A laboratory measurement that includes both the conjugated (direct) and unconjugated (indirect) forms.
  • The doctor ordered a test for total bilirubin and a liver panel.

Noun

1. an orange-yellow pigment in the bile that forms as a product of hemoglobin; excess amounts in the blood produce the yellow appearance observed in jaundice