What Causes Elevated Bilirubin Levels?

Bilirubin—including total bilirubin, direct (conjugated) bilirubin, and indirect (unconjugated) bilirubin. When red blood cells age and break down, they release hemoglobin. The heme component of hemoglobin is metabolized in the body into water-insoluble indirect bilirubin. This indirect bilirubin is then processed by the liver into water-soluble direct bilirubin, which can be excreted from the body via the kidneys in urine. So, what causes elevated bilirubin levels? Below, we address this question.

Causes of Elevated Bilirubin

1. Hemolytic Jaundice

This may occur in congenital hemolytic anemias, such as thalassemia, or acquired hemolytic anemias, including autoimmune hemolytic anemia, neonatal hemolytic disease, and hemolysis following transfusion of incompatible blood types. Additionally, hepatocellular jaundice may arise from various forms of liver injury—such as viral hepatitis, cirrhosis, toxic hepatitis, leptospirosis, and sepsis.

2. Hematologic Disorders

Hematologic diseases can lead to elevated bilirubin levels. Examples include acute hemolysis and thalassemia—both primarily cause increased indirect bilirubin, thereby raising overall bilirubin levels. Other conditions associated with hyperbilirubinemia include hemolytic anemia, malignant disorders, and neonatal jaundice. Moreover, cholestatic jaundice may also occur—caused by intrahepatic sludge-like stones, tumor thrombi, parasitic infections, drug-induced cholestasis, common bile duct stones, common bile duct strictures, inflammatory edema, tumors, or ascariasis-induced biliary obstruction.

3. Intra- or Extrahepatic Bile Duct Obstruction

Obstruction of the intra- or extrahepatic bile ducts—due to factors such as bile duct stones, tumors, inflammation, congenital cystic dilation of the bile ducts, chronic pancreatitis, benign or malignant tumors of the pancreatic head, or malignant tumors of the ampulla of Vater—can impede bile flow, leading to reflux of bilirubin into the bloodstream and impaired excretion, thereby elevating serum bilirubin levels. Patients with biliary stones often have a history of gallstones; particularly in cases of “filling-type” gallstones, contraction or peristalsis of the gallbladder may propel stones into the bile ducts—even the common bile duct—resulting in secondary obstruction.

The above outlines the main causes of elevated bilirubin. We hope this information is helpful to you.