Hyperbilirubinemia in adults

Overview of hyperbilirubinemia in adults

Hyperbilirubinemia in adults refers to an elevated level of bilirubin in the blood. Bilirubin is a yellow compound that occurs in the normal catabolic pathway that breaks down heme in red blood cells. When bilirubin levels are elevated, it can lead to jaundice, a yellowing of the skin and eyes.

Pathophysiology

Bilirubin is produced from the breakdown of hemoglobin in red blood cells. The process begins in the reticuloendothelial system, where hemoglobin is broken down into heme and globin. Heme is further degraded into biliverdin and then reduced to bilirubin. This unconjugated bilirubin is transported to the liver, where it is conjugated with glucuronic acid to become water-soluble. Conjugated bilirubin is then excreted into the bile and eventually into the intestine.

Bilirubin metabolism

Causes

Hyperbilirubinemia can be caused by several factors, which can be broadly categorized into pre-hepatic, hepatic, and post-hepatic causes:

Pre-hepatic

Pre-hepatic causes are due to increased production of bilirubin, often from hemolysis. Conditions such as hemolytic anemia, sickle cell disease, and thalassemia can lead to increased breakdown of red blood cells.

Schistocytes, indicative of hemolysis

Hepatic

Hepatic causes involve the liver's inability to properly process bilirubin. This can be due to liver diseases such as hepatitis, cirrhosis, or Gilbert's syndrome.

Post-hepatic

Post-hepatic causes are due to obstruction of bile flow, which can occur in conditions such as gallstones, pancreatic cancer, or cholestasis.

Symptoms

The primary symptom of hyperbilirubinemia is jaundice, characterized by yellowing of the skin and sclera. Other symptoms may include dark urine, pale stools, and fatigue. In severe cases, it can lead to kernicterus, a form of brain damage.

Kernicterus, a severe complication

Diagnosis

Diagnosis of hyperbilirubinemia involves measuring serum bilirubin levels. Additional tests may include liver function tests, complete blood count, and imaging studies such as ultrasound or CT scan to identify underlying causes.

Treatment

Treatment depends on the underlying cause. In cases of hemolysis, managing the underlying condition is crucial. For hepatic causes, addressing liver disease is essential. In post-hepatic cases, relieving bile duct obstruction is necessary. Phototherapy and exchange transfusion are rarely used in adults but may be considered in severe cases.

Prevention

Preventive measures include managing risk factors for liver disease, such as avoiding excessive alcohol consumption, maintaining a healthy weight, and getting vaccinated against hepatitis.

Related pages

• Jaundice
• Liver disease
• Hemolytic anemia
• Bile duct obstruction