Bilirubin

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Bilirubin

The predominant orange pigment of bile. It is the major metabolic breakdown product of heme, the prosthetic group of hemoglobin in red blood cells, and other chromoproteins such as myoglobin, cytochrome, and catalase. The breakdown of hemoglobin from the old red cells takes place at a rapid rate in the reticuloendothelial cells of the liver, spleen, and bone marrow. The steps in this breakdown process include denaturation and removal of the protein globin, oxidation and opening of the tetrapyrrole ring, and the removal of iron to form the green pigment biliverdin, which is then reduced to bilirubin by the addition of hydrogen. The formed bilirubin is transported to the liver, probably bound to albumin, where it is conjugated into water-soluble mono- and diglucuronides and to a lesser extent with sulfate. See Liver

In mammalian bile essentially all of the bilirubin is present as a glucuronide conjugate. Bilirubin glucuronide is passed through the liver cells into the bile caniculi and then into the intestine. The bacterial flora further reduces the bilirubin to colorless urobilinogen. Most of the urobilinogen is either reduced to stercobilinogen or oxidized to urobilin. These two compounds are then converted to stercobilin, which is excreted in the feces and gives the stool its brown color. See Hemoglobin

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Bilirubin

 

C33H36O6N4, a bile pigment; molecular mass 584.68. Brown crystals. Bilirubin is an intermediate product of the decomposition of hemoglobin that takes place in the macrophages of the spleen, liver, and bone marrow. It is formed by the enzymatic reduction of biliverdin. It is present in small quantities in the plasma of vertebrate animals and man (0.2–1.4 mg percent in a healthy person). When the outflow of bile is made difficult (obstruction of the bile ducts), and in some liver diseases, the bilirubin concentration increases in the blood (causing jaundice), and it appears in the urine. Hence, the presence of bilirubin in blood or urine is a diagnostic test.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

bilirubin

[‚bil·ə′rü·bən]
(biochemistry)
C33H36N4O6 An orange, crystalline pigment occurring in bile; the major metabolic breakdown product of heme.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Out of a total of 106 patient records included in the study, 37 were female out of which lab investigations including total and direct bilirubin were available in 23 cases.
Three months after the Kasai procedure, there were 120 patients (120/210, 57.1%) in the jaundice-resolved group (direct bilirubin [less than or equal to] 17.1 [micro]mol/L) and 90 patients (90/210, 42.9%) in the jaundice-unresolved group (direct bilirubin > 17.1 [micro]mol/L).
The increase in globulin (77%), total bilirubin (33%), direct bilirubin (17%), creatinine (45%) and uric acid (131%) after zeolite treatment is significantly lesser than for CuSO4 exposure.
As shown in Table 2, the continuous (natural log transformed) measure of both cumulative and 2005/2006 modeled serum PFOA concentrations were associated with increased ALT and decreased direct bilirubin (p < 0.05), but neither exposure measure was associated with GGT.
Quantitative determination of total and direct bilirubin. Biochem.
An interesting and progressive method determining the amount of both total and direct bilirubin (yellow) was described by Doumas.
Serum direct bilirubin concentration increases, as does the amount of conjugated bilirubin in the urine, leading to very dark urine.
(ii) Measurement of serum total and direct bilirubin colorimetrically according to the method of Walters and Gerarde [14], using Biodiagnostic kits, Egypt.
In our study the rats on high cholesterol diet showed a non significant increase in direct bilirubin and a highly significant increase in total bilirubin showing the hepatocellular injury (Figure 9) as is also revealed by the histopathololgical study when compared with its controls.
All it takes is a simple bike dynamo to operate the machine, which would yield the 23 medical results including glucose, urea, uric acid, heamoglobin, cholesterol, albumin, direct bilirubin, among others.
Albumin transports unconjugated bilirubin to the liver where it is metabolized using glucuronic acid into direct bilirubin. A portion of bilirubin is converted to urobilinogen in the intestine and eventually gets excreted into the urine and feces.
Other laboratory tests revealed acute hepatitis with AST 653 IU/L, ALT 1134 IU/L, alkaline phosphatase (ALP) 340 IU/L, total bilirubin 3.8 mg/dl (direct bilirubin 2.7 mg/dl).