Bilirubin, Indirect

Indirect Bilirubin by Access Medical Labs is a single-biomarker lab test that measures the level of indirect Bilirubin in the blood. Indirect bilirubin is a waste product produced by the breakdown of red blood cells. It is then transported to the liver, where it is converted into a water-soluble form called direct bilirubin.

The Indirect Bilirubin test is typically ordered as part of a liver function panel or when a healthcare provider suspects liver or blood disorders. It is a simple blood test that requires a small sample of blood to be drawn from a vein in the arm.

What is Indirect Bilirubin?

Indirect bilirubin, also known as unconjugated bilirubin, is a form of bilirubin that is produced during the breakdown of red blood cells in the body. It is insoluble in water and cannot be directly excreted by the liver. Instead, it binds to albumin, a protein in the blood, and is transported to the liver where it undergoes a process called conjugation. 

Conjugation involves the attachment of a molecule called glucuronic acid to bilirubin, converting it into a water-soluble form known as direct bilirubin or conjugated bilirubin. Indirect bilirubin levels are typically measured in blood tests to assess liver function and diagnose conditions related to bilirubin metabolism, such as jaundice, liver disease, or hemolytic anemia. The indirect (or unconjugated) bilirubin level is attained through subtraction of the conjugated bilirubin level from the total bilirubin level.

Elevated levels of indirect bilirubin can indicate a problem with the liver's ability to process bilirubin or an increased breakdown of red blood cells.

Who should get an Indirect Bilirubin test?

Indirect bilirubin testing is typically completed to evaluate liver function and can support diagnose certain disorders. It is often included in a comprehensive liver panel or liver function tests. The following patients may be ideal candidates for indirect bilirubin testing:

Patients with symptoms of liver dysfunction: Individuals experiencing symptoms such as jaundice (yellowing of the skin and eyes), dark urine, pale stools, fatigue, abdominal pain, or unexplained weight loss may benefit from indirect bilirubin testing to assess liver function.

Patients with suspected liver diseases: Individuals with a family history of liver diseases or those at risk of developing liver disorders, such as chronic hepatitis B or C infection, alcoholic liver disease, non-alcoholic fatty liver disease (NAFLD), autoimmune hepatitis, or drug-induced liver injury, may require indirect bilirubin testing.

Monitoring liver disease progression: Patients already diagnosed with liver diseases, such as cirrhosis, hepatitis, or liver cancer, may need regular monitoring of their liver function, including indirect bilirubin levels, to assess disease progression and treatment effectiveness.

Evaluating medication or toxin-induced liver damage: Certain medications, herbal supplements, or exposure to toxins can cause liver damage. Indirect bilirubin testing can help identify drug-induced liver injury or assess the extent of liver damage caused by toxins.

Newborns with jaundice: Indirect bilirubin testing is commonly performed in newborns with jaundice to determine if the bilirubin levels are within a safe range or if further evaluation and treatment are necessary.

The decision to test for indirect bilirubin should be made by a healthcare professional based on the patient's medical history, symptoms, and clinical presentation.

What is a normal Indirect Bilirubin range?

Indirect bilirubin, also known as unconjugated bilirubin, is a type of bilirubin that is not water-soluble and is bound to albumin in the bloodstream. It is produced during the breakdown of red blood cells and is eventually converted into direct bilirubin by the liver.

The normal range for indirect bilirubin levels can vary slightly depending on the laboratory and the method used for testing. However, in general, the normal range for indirect bilirubin is typically between 0.2 to 0.8 mg/dL (milligrams per deciliter) or 3.4 to 13.7 µmol/L (micromoles per liter).

The interpretation of bilirubin levels should occur in conjunction with other liver function tests and clinical symptoms. Elevated levels of indirect bilirubin may indicate various conditions such as hemolytic anemia, Gilbert's syndrome, or other liver disorders. Conversely, low levels of indirect bilirubin are generally not a cause for concern.

What does high Indirect Bilirubin indicate?

Indirect bilirubin, also known as unconjugated bilirubin, is a form of bilirubin that is produced when red blood cells are broken down in the body. It is a yellow pigment that is formed during the normal process of heme metabolism.

When bilirubin is produced, it is initially in the form of indirect bilirubin, which is not water-soluble and cannot be excreted by the body. It needs to be converted into a water-soluble form called direct bilirubin, or conjugated bilirubin, in order to be eliminated from the body through bile and urine.

A high level of indirect bilirubin in the blood may indicate a problem with the normal metabolism or excretion of bilirubin. This can occur due to various reasons, including liver dysfunction, obstruction of the bile ducts, or increased breakdown of red blood cells.

Liver dysfunction: The liver plays a crucial role in the metabolism and excretion of bilirubin. If the liver is not functioning properly, it may not be able to convert indirect bilirubin into direct bilirubin efficiently, leading to an accumulation of indirect bilirubin in the blood.

Bile duct obstruction: Obstruction of the bile ducts can prevent the flow of bile, which contains bilirubin, from the liver to the intestines. This can result in an increased level of indirect bilirubin in the blood.

Increased red blood cell breakdown: Conditions such as hemolytic anemia or certain genetic disorders can cause an increased breakdown of red blood cells. This leads to an elevated production of bilirubin, resulting in higher levels of indirect bilirubin in the blood.

A high level of indirect bilirubin alone does not provide a definitive diagnosis. Further evaluation, including additional lab tests and clinical assessment, is necessary to determine the underlying cause and appropriate treatment. Consulting with a healthcare provider or a functional medicine expert can help in interpreting the results and developing an individualized treatment plan.

What does low Indirect Bilirubin indicate?

A low indirect bilirubin level refers to a decrease in the amount of unconjugated bilirubin in the blood. Bilirubin is a yellow pigment that is produced when red blood cells break down. It is then processed by the liver and excreted in the bile.

A low indirect bilirubin level can indicate several possible situations or factors:

Healthy liver function: A low indirect bilirubin level may suggest that the liver is efficiently processing bilirubin, converting it into direct bilirubin (conjugated bilirubin) and excreting it in the bile. This can be a sign of a healthy liver.

Hemolysis: Hemolysis is the accelerated breakdown of red blood cells, leading to an increase in bilirubin production. However, if the liver is effectively processing and excreting bilirubin, the indirect bilirubin level may be low despite increased production. This can occur in conditions such as hemolytic anemia or certain medications.

Gilbert's syndrome: Gilbert's syndrome is a benign genetic condition that affects the liver's ability to process bilirubin. It can result in intermittent episodes of elevated unconjugated  bilirubin levels, but the indirect bilirubin level may be low during periods of normal bilirubin levels.

Medications: Certain medications, such as rifampin or phenobarbital, can increase the liver's ability to process bilirubin, leading to a decrease in indirect bilirubin levels.

Interpreting bilirubin levels requires considering other liver function tests and clinical symptoms. If you have concerns about your bilirubin levels, it is recommended to consult with a healthcare professional or a functional medicine expert for a comprehensive evaluation.