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

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.

bilirubin

[‚bil·ə′rü·bən]
(biochemistry)
C33H36N4O6 An orange, crystalline pigment occurring in bile; the major metabolic breakdown product of heme.
References in periodicals archive ?
In full-term neonates, bilirubin levels naturally increase in the week following delivery.
Changes in the bilirubin have been associated with liver injury during hepatic infection.
With the box, BiliScreen was around 90% as accurate as a blood test in identifying concerning levels of bilirubin in a small, 70-person clinical study.
To study the co-relation between serum total bilirubin and acute appendicitis, particularly perforated/gangrenous appendicitis and to know whether hyperbilirubinaemia can be used as a marker for diagnosing the severity of acute appendicitis, particularly appendicular perforation or gangrene in preoperative period.
Our primary outcome was neonatal significant hyperbilirubinemia indicated by a bilirubin concentration of [greater than or equal to]17 mg/dL.
A recent study in the journal Pediatrics showed BiliCam provided accurate estimates of bilirubin levels in 530 infants.
6 Altered Prothrombin time (PT), serum albumin, and serum bilirubin are evident of well-being of liver.
We used the Spearman approach to evaluate the correlations between serum bilirubin and demographics or laboratory parameters.
All neonates of either gender coming with jaundice and having serum bilirubin 13 mg/dl or greater and born to mothers having O positive blood group were included in the study.
001, respectively) compared to baseline levels, and total serum bilirubin also increased (P=0.
Jaundice is the yellow discoloration of the skin and sclera that results from accumulation of bilirubin in the skin and mucous membranes.
In contrast to numerous other antioxidants [8], protective effects of bilirubin against a wide array of aging-associated pathologic conditions have been proved in numerous recent studies.