A yellow coloring to the eyes and/or skin due to an increased level of bilirubin bilirubin: (bil-i-ROO-bun) A reddish yellow substance formed when red blood cells break apart. It is found in the bile and in the blood. Yellowing of the skin and eyes can occur with high levels of bilirubin. Also called total bilirubin. , which is a breakdown product of hemoglobin hemoglobin: A protein in the red blood cells. Hemoglobin picks up oxygen in the lungs and brings it to cells in all parts of the body. .
