BILIRUBIN - Definition

Meaning of BILIRUBIN

Pronunciation:		`bili'roobin
WordNet Dictionary

	Definition:	[n] 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

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	Synonyms:	haematoidin, hematoidin

	See Also:	animal pigment

Webster's 1913 Dictionary

	Definition:	\Bil`i*ru"bin\, n. [L. bilis biel + ruber red.] (Physiol.) A reddish yellow pigment present in human bile, and in that from carnivorous and herbivorous animals; the normal biliary pigment.

Medical Dictionary

	Definition:	Orange or yellowish pigment that is the result of breakdown of red blood cells. Excess of bilirubin in the blood produces jaundice.

Biology Dictionary

	Definition:	A red-orange pigment found in bile which is formed when old red blood cells are broken down in the liver. It can also form from other types of heme catabolism. It has the chemical formula C₃₃H₃₆N₄O₆. It is transformed from the green bile pigment biliverdin, which is directly formed from heme catabolism. Excessive bilirubin in the blood results in jaundice. Bilirubin is the by-product of breaking down hemoglobin that is measured in a blood sample. The unconjugated form of bilirubin is also called indirect bilirubin. After the liver adds a glucuronide to the unconjugated bilirubin, it is called conjugated bilirubin, also called direct bilirubin. Conjugated bilirubin is excreted into the hepatic ducts, the common bile duct and then the bowel. Serum levels of bilirubin increase when there is excessive breaking down of red blood cells, or when there is liver dysfunction. Jaundice is clinically recognizable when total bilirubin exceeds 50 umol/liter. Normal ranges: Total bilirubin 5.1-17.0 umol/L (adult) and 17-20 umol/L (newborn) Indirect bilirubin 3.4-12.0 umol/L Direct bilirubin 1.7 - 5.0 umol/L

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