Scleral Icterus · What Is It, Causes, and More

Bilirubin is normally produced when red blood cells (RBCs) break down. It is then taken up by the liver and secreted into the bile. Excessive destruction of RBCs (hemolysis) or disruption of the bilirubin pathway at some point can lead to the development of scleral icterus. 

The causes of scleral icterus tend to vary depending on the age of the affected individual. In babies, the most common cause is the physiologic jaundice of the newborn, which occurs mostly during the first week of life. The newborn’s liver is immature and cannot take up enough bilirubin. At the same time, fetal RBCs have a shorter lifespan. Combined, these factors can contribute to the buildup of bilirubin in the fetal blood, leading to scleral icterus. Newborns can also develop breast milk jaundice due to factors in the breast milk that increase the absorption of bilirubin from the intestines. Conversely, breastfeeding failure jaundice can occur in babies that do not receive a sufficient breast milk intake, as the subsequent decrease in bowel movements allows the intestines to absorb more bilirubin. When bilirubin levels rise severely in the blood of a newborn, it can travel up to their brain, cross the blood brain barrier, and ultimately lead to neurological dysfunction. 

Other, less common, causes of scleral icterus in babies and adolescents include inherited diseases, such as Gilbert’s disease and Crigler–Najjar syndrome; in these disorders, bilirubin cannot be taken up by the liver due to the absence or low activity of an enzyme responsible for bilirubin processing. Finally, viral hepatitis is the most severe disease responsible for scleral icterus and jaundice among children. Infected liver cells start to die off and lose their ability to take up and process bilirubin, leading to the accumulation of bilirubin in blood.

In the elderly, scleral icterus is most often caused by obstruction of the bile ducts, referred to as obstructive jaundice. The most common causes include gallstones and malignancy, such as pancreatic cancer and cholangiocarcinoma. 

In adults, scleral icterus can also occur due to liver dysfunction. Causes include drug-induced liver disease, parasites (liver fluke), viral hepatitis, and alcoholic and non-alcoholic cirrhosis. In these disorders, damage to the liver cells leads to liver dysfunction. As a result, bilirubin cannot be processed by the liver and therefore builds up in the blood, leading to scleral icterus.