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→Hyperbilirubinaemia
==Hyperbilirubinaemia==
==Hyperbilirubinaemia==
Bilirubin increases when the production of bilirubin exceeds the ability of the liver to recover unconjugated bilirubin from the bloodstream and process it, or when clearance of the conjugated form is altered by impaired hepatocyte processes or obstruction to the discharge of bilirubin into the intestines. Clinically, this means that hyperbilirubinaemia can be cased by heamolysis or choleostasis.
Bilirubin increases when the production of bilirubin exceeds the ability of the liver to recover unconjugated bilirubin from the bloodstream and process it, or when clearance of the conjugated form is altered by impaired hepatocyte processes or obstruction to the discharge of bilirubin into the intestines. Clinically, this means that hyperbilirubinaemia can be cased by heamolysis or choleostasis - the next step diagnostically is to establish if the inciting cause is prehepatic, hepatic or posthepatic.
==Distinguishing Conjugated from Unconjugated Bilirubin==
The '''Van de Berg test''' can be used to distinguish conjugated from unconjugated bilirubin. Plasma from an icteric animal is treated with an aqueous solution of the reagent diazotised sulphanilic acid and this produces a red-purple colour reaction. The intensity of this colour is directly proportional to the amount of water soluble (conjugated ) bilirubin in the sample. Further addition of alcohol intensifies the colour if there is non-water soluble (unconjugated) bilirubin also present. The intensified colour is directly proportional to the total amount of bilirubin present in the sample and the difference between the two readings gives the amount of unconjugated bilirubin in the sample.
The '''Van de Berg test''' can be used to distinguish conjugated from unconjugated bilirubin. Plasma from an icteric animal is treated with an aqueous solution of the reagent diazotised sulphanilic acid and this produces a red-purple colour reaction. The intensity of this colour is directly proportional to the amount of water soluble (conjugated ) bilirubin in the sample. Further addition of alcohol intensifies the colour if there is non-water soluble (unconjugated) bilirubin also present. The intensified colour is directly proportional to the total amount of bilirubin present in the sample and the difference between the two readings gives the amount of unconjugated bilirubin in the sample.