bilirubin

noun

bil·​i·​ru·​bin ˌbi-li-ˈrü-bən 

ˈbi-li-ˌrü-

: a reddish-yellow water-insoluble pigment C₃₃H₃₆N₄O₆ that is formed by the breakdown of heme, is excreted in a water-soluble form by liver cells into bile, and occurs in blood and urine especially in diseased states see jaundice

Examples of bilirubin in a Sentence

Recent Examples on the Web

Jaundice may result due to bilirubin building up in your body because your liver can’t keep up with processing it. —Bruce Y. Lee, Forbes.com, 16 Sep. 2025

OregonLive and Oregon Public Broadcasting reported that a medical examiner found that Hayden had suffered acute bilirubin encephalopathy, a neurological condition that is caused by jaundice, which was brought on by hyperbilirubinemia, an excessive amount of bilirubin in the blood. —Sean Neumann, PEOPLE, 9 Sep. 2025

High bilirubin might also indicate gallbladder disease or difficulty breaking down too many red blood cells.8 Because the CMP measures so many substances, interpretation can be tricky. —Ruth Jessen Hickman, Health, 9 Aug. 2025

An autopsy revealed that Abigail died from a high level of bilirubin in her brain, which the application points out would have manifested as jaundice. —Chris Spargo, People.com, 13 June 2025

Word History

Etymology

Latin bilis + ruber red — more at red

First Known Use

1871, in the meaning defined above

Rhymes for bilirubin

• reuben
• rubin

Medical Definition

bilirubin

noun

bil·​i·​ru·​bin ˌbil-i-ˈrü-bən, ˈbil-i-ˌ 

: a reddish-yellow, crystalline, water-insoluble pigment C₃₃H₃₆N₄O₆ that is formed by the breakdown of heme, is excreted in a water-soluble conjugated form by liver cells into bile, and occurs in blood and urine especially in diseased states (such as cirrhosis, gallstones, and hemolytic anemia)

… they may become jaundiced, their skin tinged yellow by the release of the pigment bilirubin from their damaged liver.

—Larry Thompson, Discover