Bilirubin metabolism

Applied physiology

Xia Wang, Jayanta Roy-Chowdhury, Namita Roy Chowdhury

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

Bilirubin is the breakdown product of the haem moiety of haemoglobin and other haemoproteins. Because of internal hydrogen bonding, bilirubin is water-insoluble and requires enzyme-mediated glucuronidation in the liver for biliary excretion. In normal circumstances, plasma bilirubin is mostly unconjugated and is tightly bound to circulating albumin. It is taken up by hepatocytes by facilitated diffusion, stored in hepatocytes bound to glutathione-S-transferases and conjugated to glucuronides by microsomal UGT1A1. Bilirubin glucuronides are actively transported into the bile canaliculi by the ATP-utilizing pump MRP2. Bilirubin is degraded in the intestine by bacteria into urobilinogens, which are partly excreted in the urine. Increased production, reduced uptake and low glucuronidation capacity can increase plasma unconjugated bilirubin levels. In cases of inherited or acquired deficiencies of bilirubin storage or excretion, both conjugated and unconjugated bilirubin accumulate in the plasma. Conjugated bilirubin is less tightly bound to albumin and is excreted in the urine. The capacities of the various steps of bilirubin throughput are finely balanced, and the expression of the gene products mediating these steps is coordinated by nuclear receptors.

Original languageEnglish (US)
Pages (from-to)70-74
Number of pages5
JournalCurrent Paediatrics
Volume16
Issue number1
DOIs
StatePublished - Feb 2006

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Bilirubin
Hepatocytes
Albumins
Urobilinogen
Bile Canaliculi
Facilitated Diffusion
Urine
Glucuronides
Hydrogen Bonding
Cytoplasmic and Nuclear Receptors
Glutathione Transferase
Heme
Intestines
Hemoglobins
Adenosine Triphosphate
Bacteria
Gene Expression
Water
Liver
Enzymes

Keywords

  • ABCC2
  • Bilirubin
  • Bilirubin glucuronides
  • UGT1A1

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health

Cite this

Bilirubin metabolism : Applied physiology. / Wang, Xia; Roy-Chowdhury, Jayanta; Chowdhury, Namita Roy.

In: Current Paediatrics, Vol. 16, No. 1, 02.2006, p. 70-74.

Research output: Contribution to journalArticle

Wang, Xia ; Roy-Chowdhury, Jayanta ; Chowdhury, Namita Roy. / Bilirubin metabolism : Applied physiology. In: Current Paediatrics. 2006 ; Vol. 16, No. 1. pp. 70-74.
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