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 ?
Direct bilirubin is the key factor which determines postoperative as well as long term survival in patients with malignant obstructive jaundice.
Conjugated bilirubin: a better indicator of impaired hepatobiliary excretion than direct bilirubin.
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.
Quantitative determination of total and direct bilirubin.
This allows for the determination of the total and the direct bilirubin.
Serum direct bilirubin concentration increases, as does the amount of conjugated bilirubin in the urine, leading to very dark urine.
4) Normal values of complete blood count, prothrombin time (PT), activated prothromboplastin time (aPTT), serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyl transpeptidase (GGT), total and direct bilirubin
On the other hand, no significant difference on plasma albumin, total bilirubin, direct bilirubin, creatinin, blood urea nitrogen, total protein, calcium, sodium, chloride, and magnesium levels among the normocholesterolemic, hypercholesterolemic, and mushroom-fed hypercholesterolemic rats (Table 4).
The liver, despite the effects of alcohol and tumors, was still able to produce glucuronic acid, since the direct bilirubin was also increased as well as the urinary urobilinogen (shown on Table 1).
9]/l; mean cell volume 82 fl; peripheral smear showed anisocytosis, target cells and schistocytes; lactate dehydrogenase 612 U/l; alanine transaminase 446 U/l; aspartate transaminase 191 U/l; total bilirubin 34 mmol/l; direct bilirubin 12 mmol/l; total protein 46 g/l; albumin 20 g/dl; international normalised ratio 2.
It would be helpful if a separate section were included for the evaluation of patients with elevated LFTs at baseline," the firms comments state In particular, Wyeth requested that that section "emphasize the need to differentiate the presence of direct bilirubin elevations from indirect bilirubin elevations, by obtaining both total and direct bilirubin levels.