Definition

Bilirubin is a yellow substance produced when red blood cells break down. It is stored in the gallbladder and excreted from the body through urine and feces. The process of bilirubin formation begins with the breakdown of red blood cells in the lymphatic system. Hemoglobin, a protein in red blood cells responsible for oxygen transport, is released and broken down into two components: heme (iron molecules) and globin (a blood protein). The heme portion is further degraded into biliverdin and eventually into indirect bilirubin.

Indirect bilirubin is bound to albumin protein in the blood and is soluble in fat. It is transported via the bloodstream to the liver, where it is converted into direct bilirubin by binding with glucuronide compounds, making it water-soluble. Direct bilirubin is then stored in the gallbladder before being excreted into the digestive system, contributing to the yellow coloration of stool and urine.

Bilirubin levels can be measured through a bilirubin test. Indirect bilirubin testing specifically measures bilirubin that remains in the bloodstream and has not yet been processed by the liver. This test is commonly performed in cases of jaundice, particularly in infants and children, to detect congenital blood disorders or genetic enzyme deficiencies in the liver that elevate indirect bilirubin levels. It may also be used for adult patients with jaundice to assess liver function. The test is safe and simple to perform.

Indications

An indirect bilirubin test is recommended if you or your child exhibit symptoms of jaundice, such as yellowing of the skin and eyes. Other associated symptoms include tea-colored urine, [ale or putty-colored stool, anemia or low red blood cell count, nausea and vomiting, abdominal pain or bloating, and persistent fatigue.

Doctors may recommend this test for the following purposes:

• Detecting blood disorders.
• Diagnosing congenital liver diseases in children or acquired liver conditions caused by infections or inflammation.
• Assessing gallbladder or bile duct dysfunction.
• Monitoring the effectiveness of specific therapies.

Contraindications

There are no specific contraindications for this test. However, certain medications can influence the test results, causing them to inaccurately reflect your condition. Examples of such drugs include penicillin, anti-convulsants (e.g., barbiturates, phenobarbital), high-dose salicylates, blood pressure medications (e.g., furosemide), antiviral drugs (e.g., atazanavir), and asthma medications (e.g., theophylline).

Preparation Before the Test

To ensure accurate test results, consider the following preparations:

• Avoid eating or drinking for at least four hours before the test.
• Inform your doctor about any medications you are currently taking.
• Refrain from heavy physical activities or exercise.

Test Procedure

The test involves collecting a blood sample from a vein, following these steps:

1. The healthcare provider identifies the sampling site, typically at the arm crease.
2. A tourniquet is tied around the arm, and the patient is instructed to clench their fist.
3. The skin at the arm crease is cleaned with an antiseptic solution, such as alcohol cotton or an alcohol swab.
4. Once dry, a syringe is inserted into the selected vein.
5. Approximately 0.3–0.5 mL of blood is drawn into the syringe.
6. The tourniquet is removed, and the syringe is carefully withdrawn. Pressure is applied to the injection site with alcohol cotton. The blood sample is then prepared for laboratory analysis using specialized equipment.

Normal And Abnormal Values

Indirect bilirubin levels above 0.8 mg/dL are considered abnormal and may indicate a medical condition requiring further investigation.

On the other hand, levels below 0.2 mg/dL are not typically associated with any medical concerns and do not require further action.

Results and Recommendations (Further Testing)

If your indirect bilirubin test results fall within the normal range, it indicates that the processes of bilirubin formation, decomposition, and excretion in your body are functioning properly. This reflects a healthy liver and no underlying medical conditions. To maintain this state, consider following a healthy lifestyle by getting adequate rest, and avoid taking medications without a doctor's recommendation, as certain drugs can harm the liver.

Additionally, maintain a balanced diet with the right proportion of proteins, carbohydrates, and fats. Engage in regular physical activity or exercise, and avoid smoking and alcohol consumption.

Elevated indirect bilirubin levels suggest a disruption in the body’s bilirubin processing, possibly due to:

• Excessive red blood cell breakdown, seen in conditions like sickle cell anemia, hemolytic anemia, post-transfusion reactions, erythroblastosis fetalis, and pernicious anemia.
• Enzyme deficiency in the liver, which prevents bilirubin from being converted to a soluble form (direct bilirubin). Examples include Gilbert’s syndrome and Crigler-Najjar syndrome.
• Liver damage, inflammation, or infection, which impairs bilirubin processing. Examples include hepatitis, cirrhosis and sepsis.

Low indirect bilirubin levels are typically not linked to specific medical conditions. However, certain factors can contribute to reduced bilirubin levels, including anti-inflammatory medications (e.g., aspirin), anticonvulsants (e.g., barbiturates) or regular caffeine consumption.

To determine the exact cause of abnormal indirect bilirubin levels, further tests are recommended, such as total bilirubin test, direct bilirubin test, liver function tests (AST and ALT) and complete blood test.

Consult the Right Doctor

If your indirect bilirubin test results are elevated, this indicates an underlying medical issue affecting your bilirubin processing. Normal indirect bilirubin levels suggest no significant medical conditions.

It is essential to consult a general practitioner or an internal medicine specialist for further evaluation and testing to identify the cause of increased bilirubin levels.

Want more information about laboratory, radiology, and other test results? Click here!