What is bilirubin?
Bilirubin is a bile pigment. It is produced when the red blood pigment of discarded red blood cells is broken down. It binds to the protein albumin in the blood and is thus transported to the liver. The dye bound to albumin is called “indirect” bilirubin. In the liver, the bond with the albumin is dissolved and “direct bilirubin” is produced as a bile pigment.
In the case of biliary tract diseases such as gallstones or tumors, the outflow of bile is impaired. The bilirubin cannot then be completely excreted via the bile ducts. Its concentration in the blood increases and the pigment is deposited in the tissue. This can cause the skin and especially the conjunctiva of the eyes to turn yellow (jaundice). If the bile ducts are completely blocked, the stool is light (“sand-colored”) and the urine is dark.
When is bilirubin determined in the blood?
Bilirubin – normal values
The normal range for total bilirubin depends on age:
|
Total bilirubin |
|
|
0 to 1 day |
up to 8.7 mg/dl |
|
2 days |
1.3 – 11.3 mg/dl |
|
3 days |
0.7 – 12.7 mg/dl |
|
4 to 6 days |
0.1 – 12.6 mg/dl |
|
7 days to 17 years |
0.2 – 1.0 mg/dl |
|
from 18 years |
0.3 – 1.2 mg/dl |
For direct bilirubin, a normal range of < 0.2 mg/dl applies for all age groups.
Indirect bilirubin is calculated from the difference between total bilirubin and direct bilirubin.
When is the bilirubin level low?
Too low bilirubin concentrations have no pathological value.
When is the bilirubin level elevated?
- if an increased number of blood cells die (hemolysis)
- after extensive burns
- in the case of impaired bilirubin breakdown (e.g. Meulengracht’s disease)
Indirect bilirubin and direct bilirubin increase simultaneously in the event of damage to the liver tissue. These include, for example
- Liver inflammation (hepatitis)
- Liver cirrhosis or fatty liver
- Liver cancer or liver metastases
- Poisoning with alcohol, drugs or fungi
- Damage to liver cells caused by medication or infections with salmonella or leptospira
Direct bilirubin alone is elevated when bile backs up into the liver due to blockage of the bile outflow. Causes are for example
- Narrowing of the bile ducts following inflammation
- Gallstones with obstruction of the bile duct
If the laboratory values only show the values for “total bilirubin” and “indirect bilirubin”, the value for direct bilirubin is obtained by subtracting the indirect bilirubin. Newborns have elevated indirect bilirubin levels for a few days because their liver is not yet fully functional.
Elevated bilirubin levels
You can find even more information about an elevated bilirubin level here!
What do you do if your bilirubin levels change?
If the bilirubin concentration in the blood is too high, the cause must be clarified. Slightly elevated values without symptoms indicate Meulengracht’s disease and are checked after some time. If the bilirubin level is very high, the level in the blood must be reduced quickly.
