Bilirubin (from lat. bilis - gall, ruber - red; With33N36About6N4) - one of bile pigments, yellow-orange colour in solution and brown in crystals. Bilirubin - dibasic acid soluble in chloroform, benzene; salt of bilirubin with alkaline metals soluble in water. Bilirubin is a breakdown product of hemoglobin and other remasterizada proteins formed by the restoration of the green pigment of bile biliverdin occurring mainly in the liver. Small amounts of bilirubin are in the blood plasma and tissues (see Bilirubinemia). Bilirubin accumulation in blood plasma evidence of breaking of system of its allocation is the blockage of the bile duct, hepatitis, acute liver necrosis and other Indicator of these diseases is the appearance of serum free bilirubin, with Ehrlich's reagent (see Ehrlich desireable) gives a pink coloring (direct reaction to the bilirubin). Normal bilirubin in the blood is in connection with the protein. Associated bilirubin gives staining with Ehrlich's reagent only after deposition of serum proteins ethyl alcohol (indirect reaction to bilirubin). Cm. also Bilirubinuria, Bile pigments.

Bilirubin is one of bile pigments. In human bile and carnivores prevails bilirubin, giving bile Golden-yellow color. In bile some herbivorous animals and birds contains biliverdin. Crystal bilirubin is rhomboidalis prism and plates, sometimes subtle leaflets with color from light yellow to reddish-brown; not soluble in water, glycerin and ether, slightly soluble in alcohol, it is better in chloroform, chlorobenzene and dilute alkali solutions. Golden-yellow color chloroform solutions bilirubin is stored for a significant period of time only in the dark.
The presence of two carboxylic groups in the molecule of bilirubin 1 causes the acid properties and the ability to form salts. Because of alkaline salts are soluble bilirubin, and salt ferrous metals do not dissolve, bilirubin in the form of the calcium salt (bilirubinemia lime) can come out of solution and be part of gallstones. Water-alkaline solutions B. fugitive, their Golden color quickly turns into a green due to oxidation B. in biliverdin.
For bilirubin, as for other bile pigments, typical reaction Gmelin (see Gmelin test) and its modification for urine - reaction of Rosenbach: 10 ml of urine is filtered, then straightened filter is applied drop conc. nitric acid mixed with nitrous acid. In the presence of bilirubin around the droplets formed a number of colored rings; this is most pronounced is a green ring, caused by formation of biliverdin. Greenish ring at the boundary of two liquids is formed and in that case, if the urine containing bilirubin, layering 1% alcoholic iodine solution (reaction Rosina). B. can be precipitated from the urine of limy milk. Washing of precipitates and adding acidified with hydrochloric acid alcohol, and then a few drops of chloroform, B. translate into solution. This liquid is painted in yellow color (with the reaction of Huppert - Salkovsky). Widely used in response to B. is the formation of azo dye (usually with diazotized ex tempore sulfanilic acid), which converts the liquid red with slightly reaction and blue with highly acidic or alkaline reaction.
This reaction, open Iliham (P. Ehrlich), was used by van-den-Berg (A. A. Himans van den Bergh, 1916) the basis for qualitative and quantitative determination B. in the serum. The qualitative determination of bilirubin to serum add double the amount of water and a quarter of detractive. If the liquid will be painted in red or pink color within 1 min after addition of the reagent, the reaction is considered to be "immediate", from 1 to 3 minutes - straight-time-lapse", if the color comes only by the addition of alcohol,- "indirect". The first type reactions characterized for parenchymatous and mechanical jaundice, two last - for healthy and sick form of hemolytic jaundice. In the quantitative determination of bilirubin serum proteins of blood previously precipitated double the volume of alcohol and centrifuged. To 1 ml of a transparent centrifugate add 0.25 ml of detractive and 0.5 ml of alcohol, and the resulting pink color measure kalorimetricheskim using for comparison, in much the same reaction standard solutions B. or artificially manufactured dyed standards (solutions cobalt sulfate, Rodenstock iron and other). Quantitative determination B. there is also a dilution method without protein deposition alcohol (method of Herzfeld - Bakalchuk).
The limits of contents B. in the plasma of healthy people are judged by different authors differently: from 0.2 to 0.8 mg% (Baptist, Borovskaya and Margolin, 1950), an average of 0.75 mg%, but not greater than 1.5 mg% [Lemberg and Legge (R. Lemberg, J. W. Legge), 1949]. The high content B. in the blood occurs in diseases associated with significant destruction of red blood cells (hemolytic jaundice) or failure of the excretory functions of liver parenchymal and mechanical jaundice). To investigate this liver function of the proposed test with the introduction of bilirubin. To do this, B. in the amount of 1 mg per 1 kg of weight of a body (but not more than 70 mg) dissolved in 15 ml of 0.1 M solution of carbonic sodium and injected. The blood to determine the number B. take three times: before the introduction of the b (sample I), after 5 minutes after injection (sample (II) and 4 hours later (sample (III). The difference in the content B. in samples II and I take over 100% and referred to it, the difference in the samples III and I. If liver function is not broken, this difference does not exceed 5% .
Education bilirubin occurs mainly from the hemoglobin in the reticuloendothelial system, coppersky the cells of the liver, spleen, bone marrow. B. produced in the liver and out, attaches in the liver balance glukuronova acids in the reactions with participation of orientirovat (UDF). This gives glucuronic ether (glucuronide) B. this form B. gives direct reaction with datareactor ("direct B."), while poorly soluble free B. it reacts only after the addition of alcohol ("indirect B."). Neonatal jaundice, apparently, are caused by congenital deficiency of enzymes that contribute to education glukuronida bilirubin (UDF-glucophagehydrocodone and transferase). Body, bringing B. from the body is the liver.
During the day a person is 0.2 - 0.3 g b Bilirubin, dedicated to jelchew in intestine, subject with the participation of the microbial flora restoration and through intermediate products (Meuse upholstered ruby, metabolising) becomes stercobilinogen (urobilinogen), which is partly absorbed in the large intestine, gets in the liver and in violation of its functions excreted with urine. In the oxidation of these substances form stercobilin (see) and the urobilin (see). Cm. also Gall pigments, Bile.