What is Bilirubin?

Bilirubin is a yellow pigment produced when red blood cells break down. The liver processes bilirubin and excretes it in bile. Elevated bilirubin causes jaundice (yellowing of the skin and eyes).

Types of Bilirubin

Indirect (Unconjugated): Bilirubin before liver processing
Direct (Conjugated): Bilirubin after liver processing
Total: Sum of direct + indirect

Why is it Important?

Bilirubin levels help diagnose:

Liver disease (hepatitis, cirrhosis)
Bile duct obstruction (gallstones, tumors)
Hemolytic anemia (excessive red blood cell breakdown)
Gilbert's syndrome (benign genetic condition)
Newborn jaundice

Normal Ranges

Type	Range	Unit
Total Bilirubin	0.1 – 1.2	mg/dL
Direct (Conjugated)	0.0 – 0.3	mg/dL
Indirect (Unconjugated)	0.1 – 1.0	mg/dL

What Do Abnormal Results Mean?

High Indirect Bilirubin

Common causes include:

Hemolytic anemia (red blood cell destruction)
Gilbert's syndrome (reduced liver enzyme)
Sickle cell disease
Transfusion reaction
Certain medications

High Direct Bilirubin

Common causes include:

Bile duct obstruction (gallstones, pancreatic cancer)
Hepatitis (viral, alcoholic, autoimmune)
Cirrhosis
Dubin-Johnson syndrome (rare genetic disorder)
Certain medications

Jaundice Threshold

Visible jaundice typically appears when total bilirubin exceeds 2.5-3.0 mg/dL.

When Should You Get Tested?

Bilirubin is measured in liver function panels. Your doctor may order it if you have jaundice, dark urine, pale stools, abdominal pain, or symptoms of liver disease.