conjugated bilirubin

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Related to conjugated bilirubin: Unconjugated bilirubin

di·rect re·act·ing bil·i·ru·bin

the fraction of serum bilirubin which has been conjugated with glucuronic acid in the liver cell to form bilirubin diglucuronide; so called because it reacts directly with the Ehrlich diazo reagent; increased levels are found in hepatobiliary diseases, especially of the obstructive variety.

conjugated bilirubin

See bilirubin.

conjugated bilirubin

Direct bilirubin Bilirubin chemically bound to a glucuronide in the liver, which is excreted in bile by the liver and stored in the gallbladder or transferred to the duodenum Ref range Direct BR: 0–0.3 mg/dL ↑ in Bile duct obstruction, cirrhosis, Crigler-Najjar syndrome, Dubin-Johnson syndrome, hepatitis. See Bilirubin.


an orange bile pigment produced by the breakdown of heme and reduction of biliverdin; it normally circulates in plasma and is taken up by liver cells and conjugated to form bilirubin diglucuronide, the water-soluble pigment excreted in the bile. Failure of the liver cells to excrete bile, or obstruction of the bile ducts, can cause an increased amount of bilirubin in the body fluids and thus lead to obstructive or regurgitation jaundice.
Another type of jaundice results from excessive destruction of erythrocytes (hemolytic or retention jaundice). The more rapid the destruction of red blood cells and the degradation of hemoglobin, the greater the amount of bilirubin in the body fluids.
Most bilirubin is excreted in the feces. A small amount is excreted in the urine as urobilinogen.

conjugated bilirubin
bilirubin that has been conjugated, mainly to glucuronic acid, in the liver and gives a direct result to the van den bergh test. High blood levels indicate obstructive or hepatocellular origin of the jaundice.
delta bilirubin
bilirubin diglucuronide
see conjugated bilirubin (above).
free bilirubin
see unconjugated bilirubin (below).
bilirubin toxicity
unconjugated bilirubin
bilirubin that has not been conjugated in the liver. It gives an indirect reaction to the van den bergh test. A high level of it in the blood is indicative of hemolysis or a lack of bilirubin clearance by the liver. Called also free bilirubin.
References in periodicals archive ?
13] The total and conjugated bilirubin were similarly raised across all groups.
For infants with increased conjugated bilirubin concentrations, practitioners should review the bilirubin measurements in the newborn period to help make the diagnosis.
Glucuronyltransferase, which converts unconjugated bilirubin to conjugated bilirubin, is thought to be less active in the newborn while conversely the enzyme that converts conjugated bilirubin to unconjugated bilirubin in the intestine (beta-glucuronidase) is thought to be more active (Preer and Phillip, 2011).
Conjugated bilirubin is also secreted into the renal tubules by transporters.
When the measured conjugated bilirubin fraction is >20% of the total bilirubin, the report should include a comment recommending "prompt evaluation to assess for biliary atresia".
The traditional definition of cholestasis is a conjugated bilirubin of more than 2 mg/dL or a level that's more than 20% of total bilirubin.
Conjugated bilirubin making its way through the bowel comes in contact with other chemicals (enzymes) that chop off the conjugating chemical.
Results: The mean aminotransferase levels and conjugated bilirubin levels at the time of diagnosis were significantly higher in Group I than in Group II.
Several reports regarding the study of placental metabolism of bilirubin suggest that conjugated bilirubin does not cross the placental barrier.
Chemistry tests prone to spurious results from samples containing a monoclonal protein include conjugated bilirubin, (1,2) total bilirubin, (1,3-5) creatinine, (6,7) phosphate, (8,9) calcium, (10) glucose, (11,12) urea nitrogen, (13) uric acid, (14) [gamma]-glutamyltransferase, (12) iron, (15,16) low-density lipoprotein cholesterol, (17) and high-density lipoprotein cholesterol.
Exclusion criteria were neonatal infection, haemolysis, direct hyperbilirubinaemia (serum conjugated bilirubin >17.