Bilirubin - Indirect (Unconjugated)

Overview

Bilirubin is a yellowish substance produced during the normal breakdown of red blood cells. When these cells reach the end of their lifespan, hemoglobin (the protein that carries oxygen) is released and broken down into heme and globin. The heme component undergoes further processing to form biliverdin, which is then converted into unconjugated (indirect) bilirubin. This form of bilirubin is not water-soluble and travels through the bloodstream bound to a protein called albumin. The liver takes up this unconjugated bilirubin and processes it into a water-soluble form known as conjugated (direct) bilirubin, which can then be excreted from the body. Measuring indirect bilirubin levels helps assess how well the body is managing the breakdown and processing of red blood cells.

Testing Levels:

• High ( μmol/L) - Elevated indirect bilirubin levels may indicate that the body is breaking down red blood cells more rapidly than normal or that the liver is not processing bilirubin efficiently. This can occur in conditions like hemolytic anemia, where red blood cells are destroyed prematurely, or in liver disorders that impair bilirubin processing. Symptoms may include jaundice, which is a yellowing of the skin and eyes.
  
  
• Mid - Indirect bilirubin levels within the normal range suggest that red blood cells are being broken down at a typical rate and that the liver is effectively processing bilirubin. This indicates a healthy balance in the body's management of red blood cell turnover and liver function.
  
  If indirect bilirubin levels are near the upper limit of the normal range, it could be an early sign of increased red blood cell breakdown or a mild impairment in liver function. Monitoring these levels can help detect potential issues before they become more serious.
  
  Indirect bilirubin levels near the lower limit of normal are generally not a cause for concern. They indicate that red blood cell breakdown and bilirubin processing are occurring as expected.
  
  
• Low ( μmol/L) - Low indirect bilirubin levels are uncommon and typically not problematic. They suggest that the processes of red blood cell breakdown and bilirubin processing are functioning normally.

Why We Test Bilirubin - Indirect (Unconjugated)

Testing indirect bilirubin levels can help identify conditions where there is increased destruction of red blood cells or issues with liver function. It is useful in diagnosing and monitoring diseases like hemolytic anemia and certain liver disorders.

What Affects It

Several factors can influence indirect bilirubin levels. Conditions that cause increased breakdown of red blood cells, such as hemolytic anemia, can raise these levels. Genetic disorders like Gilbert's syndrome, where the liver has a reduced ability to process bilirubin, can also lead to elevated indirect bilirubin. Additionally, liver diseases that impair the organ's ability to process bilirubin can affect these levels.

How to Improve

If indirect bilirubin levels are high or approaching the upper limit, it's important to identify and address the underlying cause. This may involve treating conditions that cause increased red blood cell destruction or managing liver disorders. Maintaining a healthy lifestyle, including a balanced diet and avoiding substances that can harm the liver, can support normal bilirubin levels. If levels are low or near the lower limit, no specific action is typically required, as this is generally not a concern.

Common Name: Bilirubin Unconjugated