Definition

A total bilirubin test measures the total bilirubin concentration in the blood. Bilirubin is a yellow fluid stored in the gallbladder and is a byproduct of red blood cell breakdown.

Bilirubin exists in two forms: direct bilirubin and indirect bilirubin. Total bilirubin is the sum of these two types.

• Direct Bilirubin

This form has undergone processing in the liver and is water-soluble. It participates in food digestion in the intestines and contributes to the pigmentation of waste products such as urine and feces.

• Indirect Bilirubin

This form remains unprocessed in the blood and has not yet passed through the liver. It is insoluble in water but can dissolve in fat.

Under normal conditions, bilirubin is metabolized in the liver and excreted via urine and feces. Only small amounts of bilirubin are typically detected in the body. However, elevated bilirubin levels during testing may signal health issues, particularly involving the liver.

Increased bilirubin levels may arise from liver damage or excessive breakdown of red blood cells. When bilirubin accumulates in the bloodstream, it leads to jaundice, characterized by a yellowish appearance of the skin, palms, and eye whites.

The total bilirubin test is one of the most common methods to evaluate bilirubin levels and can be performed in healthcare facilities.

Indications

A total bilirubin test helps assess whether the liver is functioning properly. It can be performed on adults, children, and infants.

This test is commonly used to detect liver damage or identify the underlying cause of a medical condition, such as:

• Determining the cause of jaundice in newborns.
• Identifying the cause of symptoms indicating liver damage, including jaundice, dark urine resembling strong tea, pale or clay-colored stools, and digestive problems.
• Assisting in diagnosing conditions like cirrhosis, hepatitis, or other liver diseases.
• Monitoring liver health before the onset of liver disease.
• Evaluating patients with a history of heavy alcohol consumption.
• Suspecting diseases related to bile duct obstruction.
• Tracking the effectiveness of therapy.
• Diagnosing excessive red blood cell breakdown.

Contraindications

There are no specific contraindications for the total bilirubin test, and it is suitable for everyone. However, certain medications can elevate bilirubin levels. It is advisable to inform your doctor of any medications you are taking regularly before undergoing this test.

Preparation Before the Test

To ensure accurate results, follow these preparations:

• Refrain from eating or drinking for at least four hours before the test.
• Inform and consult with your doctor about any routine medications you are taking.
• Avoid heavy physical activity or strenuous exercise prior to the test.

Test Procedure

The total bilirubin test requires a blood sample drawn from a vein. The steps for the procedure are as follows:

1. The healthcare provider identifies a site for blood collection, typically in the arm's crease.
2. A rubber band is tied around the arm, and you may be asked to make a fist.
3. The site is cleaned using an antiseptic, such as alcohol cotton or an alcohol swab.
4. After the site is dry, a needle is inserted into the vein at the chosen location.
5. Blood is drawn into a syringe or tube, usually amounting to 0.3–0.5 mL.
6. The rubber band is removed, followed by the needle.
7. The collected blood sample is sent to the laboratory for analysis using specialized equipment.

Normal and Abnormal Values

Total bilirubin levels are measured in milligrams per deciliter (mg/dL) and vary depending on age, as shown in the table below:

Table 1. Normal bilirubin levels in the blood

In adults, total bilirubin levels exceeding 1.2 mg/dL, or more than 1 mg/dL in children, are considered abnormal. Elevated bilirubin levels accompanied by symptoms may indicate an underlying medical condition.

Low bilirubin levels are typically not linked to any ongoing disease. While some studies suggest potential health risks associated with low bilirubin, further research is required for confirmation.

Results and Recommendations (Further Testing)

If your test results show bilirubin levels above the normal range, it indicates excess bilirubin in your body. This may stem from issues with the liver, bile ducts, or the breakdown of red blood cells. Conditions linked to elevated bilirubin include:

• Cirrhosis, characterized by liver scarring.
• Hepatitis, an infection or inflammation of the liver.
• Hemolytic anemia, involving excessive red blood cell breakdown.
• Blockages in the bile duct due to stones.
• Pancreatic cancer.
• Gallbladder cancer.
• Gilbert's syndrome, where bilirubin is not processed efficiently in the liver.

However, this test alone cannot definitively diagnose these conditions. Additional tests may be conducted, including:

• Complete blood count.
• Liver function tests (SGOT and SGPT).
• Urine tests.
• Liver protein assessment.
• Abdominal ultrasound.
• Liver tissue biopsy, if necessary.

For infants, the test is often performed to investigate jaundice symptoms or increased bilirubin levels caused by an underlying condition.

Consult the Right Doctor

High total bilirubin levels signify a potential health issue. Consulting a general practitioner or an internist is essential to determine the cause of abnormal bilirubin levels.

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