What is the definition or description of: blood test for jaundice?

Bilirubin : Total and direct bilirubin are yellow pigmented substances that when excessive will cause jaundice.

Increased bilirubin: Jaundice is a layman's term for elevated bilirubin in the blood, often visible as a yellow color in the eyes and skin. Bilirubin is a break down product of hemoglobin, done in the liver, so it often indicates liver problems. There are many causes of elev bilirubin, so blood tests are helpful to differentiate between these many causes.