Bilirubin

• 635-65-4
• 18422-02-1 (calcium salt)
• 93891-87-3 ( dihydrochloride)

Red solid

Fixed

• Insoluble in water
• Moderately in ethanol and diethyl ether
• Well in benzene, chloroform, chlorobenzene, carbon disulfide, acids and bases

Template: Infobox chemical / molecular formula search available

Bilirubin (Latin: bilis " bile " ruber "red") is a yellow breakdown product of the heme component of the red blood pigment hemoglobin and thus a bile pigment. The pigment is found in nature, not only in animals but also in plants; 2009 it was first detected in the seeds of tree - strelitzias.

Metabolism

Red blood cells live about 120 days, after which they are broken down in the liver and spleen. For hemoglobin, the red blood pigment that accumulates in the degradation, a yellowish substance via intermediates bilirubin is formed. Produced every day, about 300 mg of bilirubin in the human organism, of which around 80 percent from the degradation of aged erythrocytes. This is for unconjugated bilirubin (Synonyms: indirect bilirubin ) well in fat ( lipophilic), but very poorly soluble in water. It must therefore be to transport in the blood bound to albumin, a blood protein, are coupled.

Bilirubin is then coupled in the liver by the enzyme UDP - glucuronosyltransferase to glucuronic acid ( conjugated), and in these water-soluble form called " direct bilirubin " because it is no longer bound to albumin ( and directly, ie without solubilizer in aqueous medium is soluble, the indirect bilirubin, however, requires as a transport protein albumin ). So it can be excreted with the bile into the intestine. In the intestine, bilirubin is then transferred through the intermediate stages Mesobilirubinogen and stercobilinogen (Latin stercus = chair) to stercobilin. About 20 percent of the votes in the intestinal bilirubin and urobilinogen are as stercobilinogen enterohepatic circulation, are so taken up again. The majority, however, is excreted in the feces. A small portion of the absorbed urobilinogen is eliminated through the urinary tract. In liver dysfunction, these products are increasingly excreted in the urine.

Diseases

The normal value of total bilirubin in serum is below 21 micromol / L ( 1.2 mg / dl). If the serum bilirubin increased ( hyperbilirubinemia ), it comes to jaundice ( deposition of bilirubin in the skin, jaundice gr ), which turn yellow from a double normal value first the sclera (the white sclera) and later, the remaining skin. Case of severe hyperbilirubinemia finally almost all the organs that change color by the massive storage into the tissues yellow. Depending on the cause and nature of the rise in bilirubin, there are other symptoms, such as itching (Latin: pruritus).

In Crohn's Meulengracht can occur almost without clinical significance by mining disorder of bilirubin jaundice. The Rotor syndrome and Dubin -Johnson syndrome are rare inherited disorders of bilirubin metabolism.

In neonates, an increased bilirubin level is normal, the fetal hemoglobin is broken down, the liver is not yet working fully and excretion is not yet sufficient (up to the 30th week of pregnancy reaches the activity of the enzyme glucuronyl transferase, which catalyzes the conversion in the direct bilirubin, 0, 1 percent of the adult value at term approximately 1 percent). So it is at about 60 percent to a neonatal jaundice. Due to the not yet fully developed blood -brain barrier may occur ( in the cerebrum deposits in the basal ganglia ) is exceeded in age-and weight- dependent exposure limits to developmental disorders due to kernicterus. The deposited in the skin bilirubin can be converted by means of phototherapy for water-soluble Lumirubin and so resigned.