Search results
Results from the WOW.Com Content Network
Bilirubin (BR) (from the Latin for "red bile") is a red-orange compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates.This catabolism is a necessary process in the body's clearance of waste products that arise from the destruction of aged or abnormal red blood cells. [3]
When total bilirubin levels exceed 40 μmol/L, bilirubin deposition at the sclera, skin, and mucous membranes will give these areas a yellow colour, thus it is called jaundice. [6] The increase in predominantly unconjugated bilirubin is due to overproduction, reduced hepatic uptake of the unconjugated bilirubin and reduced conjugation of bilirubin.
In both settings of hemolysis mentioned above, only low levels of conjugated bilirubin may accumulate in the serum, with the amount falling within the normal limits of 4 percent of total bilirubin as conjugated bilirubin can be efficiently excreted in bile through being secreted across canalicular membrane. [25]
The level of total bilirubin is often further increased if the blood sample is taken after fasting for two days, [40] and a fast can, therefore, be useful diagnostically. A further conceptual step that is rarely necessary or appropriate is to give a low dose of phenobarbital: [41] the bilirubin will decrease substantially.
Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. [3] [6] Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme metabolism, liver dysfunction, or biliary-tract obstruction. [7]
Urobilinogen is a yellow by-product of bilirubin reduction. It is formed in the intestines by the bacterial enzyme bilirubin reductase. [1] About half of the urobilinogen formed is reabsorbed and taken up via the portal vein to the liver, enters circulation and is excreted by the kidney.
[2] [1] A bilirubin level more than 34 μmol/L (2 mg/dL) may be visible. [1] Concerns, in otherwise healthy babies, occur when levels are greater than 308 μmol/L (18 mg/dL), jaundice is noticed in the first day of life, there is a rapid rise in levels, jaundice lasts more than two weeks, or the baby appears unwell. [1]
Bilirubin levels are often mildly elevated (1–4 mg/dL). [14] If bilirubin levels are more significantly elevated, alternate or additional diagnoses should be considered such as gallstone blocking the common bile duct (common bile duct stone). [1] Less commonly, blood aminotransferases are elevated. [13]