Bilirubin, a byproduct of heme breakdown, can exist conjugated to glucuronic acid (direct) and as unconjugated (indirect). The unconjugated form is found in the blood bound to albumin and is transported to the liver. Bilirubin becomes conjugated to glucuronic acid in the liver, making it more soluble and allowing for excretion into bile. High levels of bilirubin have been correlated with jaundice and Gilbert’s syndrome while low levels have been associated with cardiovascular disease and diabetes mellitus.
Our Bilirubin Assay Kit measures total and direct bilirubin in plasma, serum, urine, or lysates. This assay is based on the Jendrassik-Grof method, in which diazotized sulfanilic acid reacts with conjugated (direct) bilirubin, forming azobilirubin that is detectable colorimetrically at 540nm. Since unconjugated (indirect) bilirubin reacts slowly, an accelerant can be added to the reaction to measure total bilirubin.