The first thing you should know is that jaundice is a word that has its etymological origin in Greek. Specifically, it comes from the adjective "ikteros", which can be translated as "yellow".
Jaundice is a term used in the field of medicine to refer to the yellowish hue of the mucous membranes and skin caused by an increase in bile pigments found in the blood.
Jaundice, therefore, is usually linked to an increase in the level of bilirubin (a yellow bile pigment) in the tissues. Bilirubin tends to accumulate in those tissues that have a high amount of elastic fibers, such as the conjunctiva and palate.
It is important to understand that jaundice is not a disease : it is a clinical sign that reveals the existence of a pathological process that occurs in some part of the normal metabolism of bilirubin.
This metabolic process begins with the degradation of red blood cells once they have completed their life cycle. In this instance these cells break down and release their contents into the bloodstream. This allows macrophages (cells that undergo phagocytosis) to phagocytose hemoglobin , a protein that was present in red blood cells. In this way they break it down into the heme group and globin . The heme group, in turn, undergoes a catalyzed oxidation that produces, among other elements, biliverdin , which ends up being reduced into bilirubin.
Bilirubin can appear as simple or unconjugated bilirubin , or be conjugated with glucuronic acid ( conjugated bilirubin ). Depending on which type of bilirubin is detected in excess, jaundice takes on different names.
Prehepatic jaundice arises from a release of unconjugated bilirubin linked to hemolytic anemia or from an increase in simple bilirubin due to a low level of albumin . Hepatic jaundice , meanwhile, appears due to problems in the liver , while posthepatic jaundice is linked to the slow transit of bilirubin caused by stones in the gallbladder or another disorder.
It should be noted that jaundice is common in newborn babies, and can be physiological (due to lack of maturity of metabolism) or pathological (requires medical treatment).