DIRECT BILIRUBIN, 250 mL

PRINCIPLE

Total bilirubin is determined by reaction with diazotized sulphanilic acid, in the presence of caffeine, with the final production of an azopigment. The same reaction, but in the absence of caffeine, is used to measure direct bilirubin.

DIAGNOSTIC USE

Bilirubin is a metabolic hemoglobin product which is transported to the liver, where there is conjugated with glucuronic acid, and it is secreted through bile. This conjugated bilirubin is the direct bilirubin, while unconjugated bilirubin is called indirect bilirubin. The total serum bilirubin is direct bilirubin plus indirect bilirubin. Direct bilirubin increases in biliary obstruction, cirrhosis, and hepatitis. High level of indirect or total bilirubin may indicate hemolytic diseases, physiological neonatal jaundice, Gilbert’s disease or fructose intolerance. A single test result could not be used to make a clinical diagnosis. It should integrate clinical and laboratory data.