Guide to Total Bilirubin

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Updated: 05/22/2025|12 min read

Summary

Bilirubin is a natural product of old red blood cell breakdown (hemolysis); it can reflect both liver function and hemolysis (excessive red blood cell destruction) and can serve as an antioxidant.

Why It Matters

Total bilirubin provides insight into both liver health and red blood cell turnover in your body.

When red blood cells complete their lifecycle (approximately 120 days), they're broken down in the spleen and liver. During this process, hemoglobin is converted into bilirubin. This "unconjugated" or indirect bilirubin travels through your bloodstream attached to protein albumin. When it reaches your liver, it's processed into a more water-soluble form called "conjugated" or direct bilirubin. At this point, it can be excreted into bile and eventually passed through your stool.

High total bilirubin levels (hyperbilirubinemia) can indicate several potential issues:

Liver dysfunction or disease, which may affect the organ's ability to process bilirubin
Blockages in the bile ducts that prevent proper elimination of bilirubin
Excessive breakdown of red blood cells (hemolytic anemia)
Genetic conditions that affect bilirubin processing and transport

Very low bilirubin levels might suggest:

Metabolic dysfunction
Potential cardiovascular risks
Certain medications or supplements affecting bilirubin metabolism

Slightly elevated bilirubin levels aren't always cause for concern. Although the research is early, there's evidence that mildly elevated bilirubin may actually serve as an antioxidant in the body.

Associated Symptoms

Bilirubin levels themselves are laboratory findings rather than medical conditions. However, abnormal levels may be associated with various health conditions, each with their own symptoms.

Common symptoms that may indicate conditions associated with elevated bilirubin:

Yellowish skin and eyes (jaundice): The most recognizable sign of high bilirubin, occurs when excess bilirubin deposits in tissues
Dark urine: May be caused by increased excretion of water-soluble bilirubin through the kidneys
Lightly colored stool: May result from decreased bilirubin in the intestines due to bile duct obstruction
Severe abdominal pain or tenderness: May indicate liver inflammation, gallstones, or bile duct blockage
Mental changes: Drowsiness or confusion can occur in severe cases as bilirubin affects brain function
Bloody or tarry black stool: May suggest gastrointestinal bleeding that can increase bilirubin from red blood cell breakdown
Bloody vomit: Another potential sign of gastrointestinal bleeding causing increased bilirubin
Fever: Can accompany liver inflammation or infection that can disrupt bilirubin processing
Itchy skin: May result from bile salts depositing in the skin when bile flow is obstructed
Easy bruising: May reflect potential liver dysfunction affecting clotting factor production

Very low bilirubin levels typically don't cause noticeable symptoms but may be associated with underlying conditions that have their own symptoms.

It's important to understand that many factors can cause these symptoms, and bilirubin levels are just one piece of diagnostic information. The presence of symptoms alongside abnormal bilirubin levels provides context for further investigation, but additional testing is typically needed to determine the underlying cause.

Clinical Ranges

Lab Reference Ranges:

10-19 Years: 0.2-1.1 mg/dL
≥20 Years: 0.2-1.2 mg/dL

Lifestyle Choices That Can Impact It

Activities that may improve bilirubin levels:

Regular moderate exercise supports healthy liver blood flow and enhances the liver's ability to process bilirubin.
Maintaining a healthy weight can reduce fat accumulation in the liver, which can interfere with bilirubin processing.
Drinking enough fluids helps maintain blood volume and supports efficient transport of bilirubin to the liver.
Getting enough sleep (7-9 hours) allows proper liver recovery and optimal bilirubin metabolism during rest periods.
Limiting alcohol consumption minimizes stress on liver cells responsible for bilirubin processing.

Activities that may harm bilirubin levels:

Prolonged fasting or extreme calorie restriction can stress liver function and alter bilirubin metabolism.
Crash dieting and ketogenic diets can increase bilirubin due to altered fat metabolism
Extreme physical exertion may increase red blood cell breakdown and overwhelm normal bilirubin processing.
Dehydration concentrates bilirubin in the blood and makes it harder for the liver to process.
Chronic stress impairs liver function through stress hormone effects and reduced blood flow.

Other Factors That Can Impact It

Genetic Conditions

The following factors can affect your body's ability to transport or break down bilirubin. This can lead to higher levels.

Crigler-Najjar Type 1 - severe and requires lifelong treatment, while Type 2 is milder.
Dubin-Johnson and Rotor syndromes cause elevated direct bilirubin but are usually benign.
Gilbert's syndrome (affects 3--7 percent of the population)
Rotor syndrome

Medications and Supplements

The following can increase bilirubin levels:

Azathioprine
Chlorpropamide
Cholinergics
Codeine
Diuretics
Epinephrine
MAO inhibitors
Meperidine
Methotrexate
Methyldopa
Morphine
Nicotinic acid
Oral contraceptives
Phenothiazines
Quinidine
Rifampin
Salicylates
Steroids
Sulfonamides
Theophylline

Others can lower bilirubin levels, including:

Barbiturates
Caffeine
High-dose salicylates
Penicillin

Other Factors

Acute illness or infection
Old age
High altitude
Gender (slightly higher in males)
Recent surgery
Seasonal variations

Testing Accuracy and Stability

Factors That Can Affect the Accuracy of Your Test

Alcohol consumption should be avoided for at least 24 hours
When you took the test (tests are typically performed in the morning for the most reliable result)
Whether you recently had an intense workout
You took certain medications within twenty-four hours of the test
Exposure to light can affect the sample as bilirubin is light-sensitive

Best Practices for Testing

Take the test in the morning, if possible (between 8--10 am).
Fast for 8-12 hours before the test.
- Labs recommend fasting despite its tendency to increase values because it provides a standardized condition for testing, allowing for the comparison of values over time.
Avoid intense exercise 24 hours before the test.
Stay hydrated.
Tell your provider about any medications or supplements you're taking.
Consider taking the testing again if you have unexpected results.

How it Relates to Other Markers

Other tests can give clues about diseases or other conditions when they're combined with total bilirubin results. These tests include:

Liver function tests (AST, ALT, ALP, GGT): High levels of these in addition to high bilirubin may point to liver damage or dysfunction.
Direct/indirect bilirubin ratio: This measures how much direct (conjugated) and indirect (unconjugated) bilirubin is in your blood.
Albumin: This is a protein your liver produces. High levels of albumin and bilirubin may indicate your gall bladder, liver, or bile duct is blocked, damaged or diseased.
PT/INR: This test measures how quickly your blood clots. If your liver is damaged, it may not produce enough proteins to allow your blood to clot normally.

Follow-up Considerations

You should always talk to your doctor if you have medical concerns or questions.

When Re-Testing May be Appropriate

If your levels are mildly elevated but you don't have any symptoms, your doctor may recommend:

Repeating the testing in 2-4 weeks.
Observing whether levels vary based on fasting status.
Tracking your patterns over time.

If your levels are significantly high or you have symptoms, your doctor may suggest:

Taking a complete liver panel test.
Scheduling any imaging studies your provider recommends.
Monitoring more often.

If your levels are consistently low, they may suggest:

Getting an oxidative stress evaluation. Low levels of bilirubin can indicate oxidative stress in the body, which can potentially damage cells.
Considering a cardiovascular risk assessment. Very low levels of bilirubin can signal a risk of cardiovascular conditions.
Getting a nutritional evaluation. Certain foods can increase or decrease your bilirubin levels.

Additional Testing Your Doctor May Consider

Hepatitis panel
Hemolysis workup
Genetic testing for inherited conditions
Imaging studies (ultrasound, CT, MRI) of liver and bile ducts
Iron studies
Autoimmune markers

Bibliography

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