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Encyclopedia > Bilirubin
The structure of bilirubin

Bilirubin Image File history File links Bilirubin. ...

Systematic (IUPAC) name
3-[2-[(3-(2-carboxyethyl)-5-[(3-ethenyl-
4-methyl-5-oxo-pyrrol-2-ylidene)methyl]-
4-methyl-1H-pyrrol-2-yl]methyl)-5-[(4-ethenyl-
3-methyl-5-oxo-pyrrol-2-ylidene)methyl]-
4-methyl-1H-pyrrol-3-yl] propanoic acid
Identifiers
PubChem         250
Chemical data
Formula C33H36N4O6 
Mol. weight 584.662
Complete data

Bilirubin is a yellow breakdown product of normal heme catabolism. Its levels are elevated in certain diseases and it is responsible for the yellow color of bruises and the brown color of feces. Bilirubin reduction in the gut leads to a product called urobilinogen, which is excreted in urine. IUPAC nomenclature is a systematic way of naming organic chemical compounds. ... PubChem is a database of chemical molecules. ... This article or section does not cite any references or sources. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... Physical properties Hazard properties Chemical properties Pharmacological properties Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) a  PubChem 250 Categories: | | | ... Breakdown may refer to: Look up Breakdown in Wiktionary, the free dictionary. ... Structure of Heme b A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. ... Anabolism is the aspect of metabolism that contributes to growth. ... A bruise or contusion or ecchymosis is a kind of injury, usually caused by blunt impact, in which the capillaries are damaged, allowing blood to seep into the surrounding tissue. ... Feces, faeces, or fæces (see spelling differences) In humans, defecation may occur (depending on the individual and the circumstances) from once every two or three days to several times a day. ... Urobilinogen is a colourless product of bilirubin reduction. ...

Contents

Chemistry

Bilirubin consists of an open chain of four pyrroles (tetrapyrrole); by contrast, the heme molecule is a ring of four pyrroles, called porphyrin. Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N. Pyrroles are components of larger aromatic rings, including the porphyrins of heme, the chlorins and bacteriochlorins of chlorophyll, and the corrin ring of vitamin B12. ... Core porphyrin structure 3D representation A porphyrin is a heterocyclic macrocycle made from 4 pyrrole subunits linked on opposite sides (α position) through 4 methine bridges (=CH-). The macrocycle, therefore, is more aromatic than the related corrins, chlorins (2,3-dihydroporphyrin) and bacteriochlorins (2,3,12,13-tetrahydroporphyrin). ...


Bilirubin is very similar to the pigment phycobilin used by certain algae to capture light energy, and to the pigment phytochrome used by plants to sense light. All of these contain an open chain of four pyrroles. Natural Ultramarine pigment in powdered form. ... Phycobilins are the chromophores of phycobiliproteins (photosynthetic pigments) found in cyanobacteria and in the chloroplasts of red algae, glaucophytes and some cryptomonads (though not in green algae and higher plants). ... Phytochrome is a photoreceptor, a pigment that plants use to detect light. ...


Like these other pigments, bilirubin changes its conformation when exposed to light. This is used in the phototherapy of jaundiced newborns: the illuminated version of bilirubin is more soluble than the unilluminated version. Light therapy or phototherapy consists of exposure to specific ranges of light wavelengths (using lasers or LEDs), or very bright, full-spectrum light, for a prescribed amount of time. ...


Several textbooks and research articles show incorrect chemical structures for the two isoforms of bilirubin. [1] In biology, a protein isoform is a version of a protein with some small differences, usually a splice variant or the product of some posttranslational modification. ...


Function

Bilirubin is created by the activity of biliverdin reductase on biliverdin. Bilirubin, when oxidized, reverts to become biliverdin once again. This cycle, in addition to the demonstration of the potent antioxidant activity of bilirubin, has led to the hypothesis that bilirubin's main physiologic role is as a cellular antioxidant [2]. Biliverdin reductase is an enzyme (EC 1. ... Biliverdin is a green pigment formed as a byproduct of hemoglobin breakdown. ...


Metabolism

Erythrocytes (red blood cells)generated in the bone marrow are destroyed in the spleen when they get old or damaged. This releases haemoglobin, which is broken down to haem, as the globin parts are turned into amino acids. The haem is then turned into unconjugated bilirubin in the macrophages of the spleen. It is then bound to albumin and sent to the liver. Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... Grays Anatomy illustration of cells in bone marrow. ... The spleen is an organ located the abdomen, where it functions in the destruction of old white blood cells and holding a reservoir of blood. ... A hæm or heme is a metal-containing cofactor that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... A macrophage of a mouse stretching its arms to engulf two particles, possibly pathogens Macrophages (Greek: big eaters, makros = long, phagein = eat) are white blood cells, more specifically phagocytes, acting in the nonspecific defense as well as the specific defense system of vertebrate animals. ... You may be looking for albumen, or egg white. ... The liver is an organ present in vertebrates and some other animals. ...


In the liver it is conjugated with glucuronic acid, making it water soluble. Much of it goes into the bile and thus out into the small intestine. Some of the conjugated bilirubin remains in the large intestine and is metabolised by colonic bacteria to stercobilinogen and then oxidised to stercobilin. The α-D form of glucuronic acid. ... The reddish-brown color of human feces is derived from stercobilin, a tetrapyrrole chemical compound created by bacterial action on bilirubin and subsequent oxidation. ...


Some is reabsorbed, and excreted in the urine as urobilinogen and the oxidised form, urobilin. If the liver’s function is impaired, or biliary drainage blocked, some of the conjugated bilirubin appears in the urine, turning it dark amber. Urobilinogen is a colourless product of bilirubin reduction. ... Urobilin is a yellow breakdown product of haem (heme in American English) catabolism. ...


Bilirubin toxicity

Unconjugated hyperbilirubinaemia in the neonate can lead to accumulation of bilirubin in certain brain regions, a phenomenon known as kernicterus, with consequent irreversible damage to these areas manifesting as various neurological deficits, seizures, abnormal reflexes and eye movements. Aside from specific chronic medical conditions that may lead to hyperbilirubinaemia, neonates in general are at increased risk since they lack the intestinal bacteria that facilitate the breakdown and excretion of conjugated bilirubin in the feces (this is largely why the feces of a neonate are paler than those of an adult). Instead the conjugated bilirubin is converted back into the unconjugated form by the enzyme b-glucoronidase and a large proportion is reabsorbed through the enterohepatic circulation. Kernicterus is damage to the brain centers of infants caused by jaundice. ... This article is about the medical term, epileptic seizure, as distinct from psychogenic non-epileptic seizure. ... A reflex action or reflex is a biological control system linking stimulus to response and mediated by a reflex arc. ... Jaundice, technically known as icterus, is yellowing of the skin, sclera (eyes) and mucous membranes caused by increased levels of bilirubin in the system. ... Enterohepatic circulation, is the excretion of a drug (or a metabolite of it) through the bile to be re-absorbed in the gut and sent again to the liver along the portal vein, so the excretion-reabsortion cycle can start again. ...


Bilirubin benefits

Reasonable levels of bilirubin can be beneficial to the organism. Evidence is accumulating that suggests bilirubin can protect tissues against oxidative damage caused by free radicals and other reactive oxygen species. Statistical analysis of people with high normal or slightly elevated bilirubin levels in blood shows that they have a lower risk of developing cardiovascular diseases. In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ... Reactive oxygen species (ROS) include oxygen ions, free radicals and peroxides both inorganic and organic. ...


Bilirubin blood tests

Bilirubin is in one of two forms:

Abb. Name Soluble? Reaction
"BC" conjugated or direct Yes (bound to glucuronic acid) Reacts directly when dyes are added to the blood specimen.
"BU" unconjugated or indirect No Free bilirubin does not react to the reagents until alcohol is added to the solution. Therefore, the measurement of this type of bilirubin is indirect. (It is transformed into a soluble or direct form, in the liver. )

Total bilirubin measures both BU and BC. Total and direct bilirubin levels can be measured from the blood, but indirect bilirubin is calculated from the total and direct bilirubin. The α-D form of glucuronic acid. ...


To further elucidate the causes of jaundice or increased bilirubin, it is usually simpler to look at other liver function tests (especially the enzymes ALT, AST, GGT, Alk Phos), blood film examination (hemolysis, etc.) or evidence of infective hepatitis (e.g., Hepatitis A, B, C, delta E, etc). Liver function tests (LFTs or LFs), which include liver enzymes, are groups of clinical biochemistry laboratory blood assays designed to give information about the state of a patients liver. ... Alanine transaminase or ALT is an enzyme (EC 2. ... Aspartate transaminase (AST) also called Serum Glutamic Oxaloacetic Transaminase (SGOT) or aspartate aminotransferase (ASAT) (EC 2. ... Gamma glutamyl transpeptidase (GGT) (EC 2. ... Ball and stick model of alkaline phosphatase Alkaline phosphatase (ALP) (EC 3. ... Blood films, Giemsa stained A blood film or peripheral blood smear is a slide made from a drop of blood, that allows the cells to be examined. ... Hemolysis (alternative spelling haemolysis) literally means the excessive breakdown of red blood cells. ... Hepatitis (plural hepatitides) implies injury to liver characterised by presence of inflammatory cells in the liver tissue. ...


Bilirubin is an excretion product, and the body does not control levels. Bilirubin levels reflect the balance between production and excretion. Thus, there is no "normal" level of bilirubin.


Bilirubin is broken down by light, and blood collection tubes (especially serum tubes) should therefore be protected from such exposure.


Interpretation

The reference range for total bilirubin is 2 - 14 μmol/L or 0.3 - 1.9 mg/dL. For direct bilirubin, it is 0 - 4 μmol/L or 0 - 0.3 mg/dL. A reference range is a set of values used by a health professional to interpret a set of medical test results. ...


Mild rises in bilirubin may be caused by

  • Hemolysis or increased breakdown of red blood cells.
  • Gilbert's syndrome - a genetic disorder of bilirubin metabolism which can result in mild jaundice, found in about 5% of the population.

Moderate rise in bilirubin may be caused by Hemolysis (alternative spelling haemolysis) literally means the excessive breakdown of red blood cells. ... Gilberts syndrome (pr. ...

  • Drugs (especially anti-psychotic, some sex hormones, and a wide range of other drugs).
  • Hepatitis (levels may be moderate or high).

Very high levels of bilirubin may be caused by This article does not cite its references or sources. ... The term antipsychotic is applied to a group of drugs used to treat psychosis. ... Sex hormones are hormones that affect the reproductive system. ... Hepatitis (plural hepatitides) implies injury to liver characterised by presence of inflammatory cells in the liver tissue. ...

Cirrhosis may cause normal, moderately high or high levels of bilirubin, depending on exact features of the cirrhosis Jaundice, also known as icterus (adjective:Icteric), is yellowing of the skin, sclera (the white of the eyes) and mucous membranes caused by increased levels of bilirubin in the human body. ... Jaundice, also known as icterus (attributive adjective: icteric), is a yellowing of the skin, conjunctiva (a clear covering over the sclera, or whites of the eyes) and mucous membranes caused by increased levels of bilirubin in red blooded animals. ... Cirrhosis of the liver is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrotic scar tissue as well as regenerative nodules, leading to progressive loss of liver function. ... Crigler-Najjar syndrome is a disorder of bilirubin metabolism. ... Dubin-Johnson syndrome is an autosomal recessive disease which presents shortly after birth with an increase of conjugated bilirubin without elevation of liver enzymes (ALT, AST). ... Cirrhosis of the liver is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrotic scar tissue as well as regenerative nodules, leading to progressive loss of liver function. ...


Indirect bilirubin is fat soluable and direct bilirubin is water soluable.


Jaundice

Jaundice may be noticeable in the sclera (white) of the eyes at levels above about 30-50 μmol/l, and in the skin at higher levels. Jaundice is classified depending upon whether the bilirubin is free or conjugated to glucuronic acid into: Jaundice, also known as icterus (attributive adjective: icteric), is a yellowing of the skin, conjunctiva (a clear covering over the sclera, or whites of the eyes) and mucous membranes caused by increased levels of bilirubin in red blooded animals. ... Schematic diagram of the human eye. ... The α-D form of glucuronic acid. ...

  • Conjugated jaundice
  • Unconjugated jaundice

Cultural references

Bilirubin was used as a wordplay in the novel The Silence of the Lambs. The incarcerated psychopathic psychiatrist Hannibal Lecter assists the FBI in capturing a killer. Lecter gives the name of the killer as "Billy Rubin". After Lecter escapes from custody, they find a piece of paper in his cell on which he had written his warden's name (Chilton) and, from the C,H,N,O in the name, given the formula for bilirubin. This article or section does not cite any references or sources. ... Hannibal Lecter is a fictional character in a series of novels by author Thomas Harris. ...


In Juan Luis Guerra's song, 'Me sube la bilirrubina', the protagonists' Bilirubin levels increase as a result of unrequited love. Juan Luis Guerra (born June 7, 1957 in Santo Domingo, Dominican Republic) is one of the most internationally recognized Dominican singer/songwriters. ...


German industrial band Einstürzende Neubauten have a song called Bili Rubin Einstürzende Neubauten is an experimental music band, originally from West Berlin, formed in 1980. ...


References

  • Baranano et al. "Biliverdin reductase: A major physiologic cytoprotectant" Proc Natl Acad Sci U S A. 2002 December 10; 99(25): 16093–16098.

See also


  Results from FactBites:
 
MedlinePlus Medical Encyclopedia: Bilirubin (660 words)
Heme is converted to bilirubin, which is then carried by albumin in the blood to the liver.
Conjugated bilirubin is released into the bile by the liver and stored in the gallbladder, or transferred directly to the small intestines.
Jaundice is the discoloration of skin and the sclera of the eye, which occurs when bilirubin accumulates in the blood at a level greater than approximately 2.5 mg/dL.
Bilirubin: The Test (701 words)
Too much bilirubin may mean that too much is being produced (usually due to increased destruction of red blood cells (hemolysis) or that the liver is incapable of adequately removing bilirubin in a timely manner (due to blockage of bile ducts, liver diseases ((such as cirrhosis, acute hepatitis), or inherited problems with bilirubin handling).
A bilirubin level may be ordered when a patient shows evidence of jaundice (yellowing of eyes or skin), has a history of drinking excessive amounts of alcohol, suspected drug toxicity, or has been exposed to hepatitis viruses.
If conjugated bilirubin is elevated, there may be some kind of blockage of the liver or bile duct, hepatitis, trauma to the liver, a drug reaction, or long-term alcohol abuse.
  More results at FactBites »

 
 

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