unconjugated bilirubin

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Related to unconjugated bilirubin: indirect bilirubin

in·di·rect re·act·ing bil·i·ru·bin

the fraction of serum bilirubin which has not been conjugated with glucuronic acid in the liver cell; so called because it reacts with the Ehrlich diazo reagent only when alcohol is added; increased levels are found in hepatic disease and hemolytic conditions.

unconjugated bilirubin

the majority of bilirubin in plasma. 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 ?
To prevent unconjugated bilirubin being deposited in tissues it is bound to albumin (a protein) and then transported in the blood to the liver where it is converted to its conjugated form by an enzyme called glucuronyltransferase (England, 2010; McIntosh and Stenson, 2008).
4) Reabsorption of blood following internal haemorrhage or haematomas may also generate a transient rise in unconjugated bilirubin.
In the setting of most liver diseases, hemoglobinuria, increases in primarily unconjugated bilirubin, and otherwise unexplained high LDH measurements generally are the most useful in diagnosing hemolysis.
In the newborn period, immaturity of the liver and the increased breakdown of red blood cells mean that most healthy babies have a raised unconjugated bilirubin level.
Our interpretation of the binding isotherms requires that both the Bf probe and unconjugated bilirubin are monomers in solution.
9) found that enzymatic and some Jaffe procedures demonstrated similar slight positive or negative interferences with unconjugated bilirubin, whereas other Jaffe procedures exhibited >10% negative interference.
A study showed that the change of amino acid at either codon 130 (Asn130Asp) or codon 174 (Val174Ala) of SLCO1B1 may reduce elimination of unconjugated bilirubin (54).
Bilirubin proficiency testing using specimens containing unconjugated bilirubin and human serum: results of a College of American Pathologists study.
Pooled human serum was supplemented with unconjugated bilirubin (>99%; Bilirubin, Mixed isomers; Sigma-Aldrich).
Laboratory findings of low Hb, increased reticulocytosis, increased unconjugated bilirubin and LD, and decreased haptoglobin are suggestive of hemolytic anemia (5).
Kernicterus could usually be prevented by administering an exchange transfusion to infants whose serum unconjugated bilirubin concentration reached 341 [micro]mol/L (20 mg/dL), but the diagnostic specificity of 341 [micro]mol/L (20 mg/dL) was quite poor.