Bilirubin and Biliverdin - Meaning, Difference Between Them

Human blood is a type of connective tissue that moves throughout the body constantly and performs several functions, from transporting nutrients, and oxygen, to fighting off infections to removing waste. 

Haemoglobin is an essential iron-rich protein present in red blood cells. It is responsible for carrying oxygen from the lungs to all body parts. During the degradation or breakdown process for the red blood cells (after completing the total life span of around 120 days) haemoglobin, bilirubin and biliverdin are produced. Keep reading this article to learn about bilirubin and biliverdin and the differences between bilirubin and biliverdin.

What is Bilirubin?

Bilirubin is a yellowish-coloured pigment and a metabolite of heme. It is formed due to the breakdown of the red blood cells. 

Once the lifecycle of the red blood cells is complete, the haemoglobin present in them undergoes degradation, where the biliverdin formed undergoes further reduction to give bilirubin as an end product.

Accumulation of the bilirubin in the body tissues can be a warning sign of a liver condition. High or increased bilirubin levels in the body can cause serious conditions like hyperbilirubinemia and jaundice. 

There are two types of bilirubin which include:

  1. Unconjugated bilirubin (Indirect Bilirubin) :  This type of bilirubin is formed when the red blood cells break down, which travels in the blood and into the liver. Unconjugated or indirect bilirubin is insoluble in water and is extremely toxic to the body. A spike in unconjugated bilirubin can cause unconjugated hyperbilirubinemia.
  2. Conjugated bilirubin (Direct Bilirubin) : When unconjugated bilirubin is conjugated by the addition of glucuronic acid, conjugated or direct bilirubin is formed. Conjugated or direct bilirubin is easily soluble in water and is non-toxic to the body. Increased conjugated or direct bilirubin levels in the body lead to conjugated hyperbilirubinemia.

A spike in bilirubin may be due to various liver problems or other medical conditions. Depending on the symptoms, the doctor will examine and diagnose the cause leading to a high bilirubin level.

What is Biliverdin?

Biliverdin is a green-coloured pigment found in the bile. During the breaking down of heme, biliverdin is formed as a byproduct. This biliverdin undergoes further breakdown through biliverdin reductase to form bilirubin. Bilirubin, upon oxidation, changes back to biliverdin. 

A high level of biliverdin is usually caused due to improper conversion of biliverdin to bilirubin. Biliverdin spike may also be due to genetic mutation of the biliverdin reductase A-gene.

How are bilirubin and biliverdin derived?

Bilirubin and biliverdin are derived from the breaking down of the haemoglobin (heme degradation) present in senescent red blood cells. The heme in the senescent red blood cells undergoes degradation by heme oxygenase, leading to the formation of biliverdin, carbon monoxide, and iron. The biliverdin so formed undergoes further reaction where it is converted to bilirubin (unconjugated) by biliverdin reductase.

Difference between Bilirubin and Biliverdin

Parameter

Bilirubin Biliverdin

Colour

Yellowish Green

Formation reaction catalysed by

Biliverdin reductase Heme oxygenase
Symptoms are seen in the case of its rise
  1. Darkened urine
  2. The pale colour of the stools 
  3. Nausea
  4. Vomiting
  5. Weight loss
  6. Fever
  7. Appetite loss.
Green-coloured skin, urine, and other body fluids (green jaundice).
Causes
  1. Jaundice
  2. Gallstones
  3. Hemolytic anaemia
  4. Liver diseases like Hepatitis, Cirrhosis
  5. Misfunctioning of the liver
  6. Gilbert’s syndrome
  7. Problems in the bile duct
  8. Drug reaction
  9. Blood transfusion reaction
Genetic mutation of the biliverdin reductase A-gene
Test for diagnosis
  1. Physical examination
  2. Bilirubin test
  1. Colour changes
  2. Lab tests
Disease caused due to its increase
  1. Hyperbilirubinemia
  2. Jaundice
  3. Kernicterus
Hyperbiliverdinemia (green jaundice)

Takeaway

Bilirubin and biliverdin are formed due to heme breakdown and are essential for the body. Where bilirubin is the end product of heme breakdown, biliverdin is a byproduct. Both bilirubin and biliverdin are found in the bile, which is responsible for digestion.

Jaundice is the most common condition caused due to high levels of biliverdin and bilirubin; hence, reducing the risk of its increase is essential. 

Now that you must be clear about the diseases caused due to the derangement in the levels of bilirubin and biliverdin reach out to HexaHealth in case you notice any such symptoms that point towards a liver or other disorders. HexaHealth has a team of experienced professionals who will help manage your condition without hassle. So get in touch with us right now!

Frequently Asked Questions

Are Bilirubin and Biliverdin same?

No, bilirubin and biliverdin are not the same. They are two different pigments found in the bile.

What are Bilirubin and Biliverdin?

Bilirubin and biliverdin are compounds formed during heme breakdown (degradation of heme).

Where are Bilirubin and Biliverdin found?

Biliverdin and bilirubin are found in the bile juice secreted from the liver and are responsible for digestion.

What is the role of Bilirubin and Biliverdin?

The role of Bilirubin and Biliverdin is to protect the liver from the building up of lipids and liver diseases.

What may happen if Bilirubin and Biliverdin get raised?

A rise in bilirubin and biliverdin may cause Hyperbilirubinemia and Hyperbiliverdinemia, respectively.

What is the difference between Bilirubin and Biliverdin?

The difference between bilirubin and biliverdin is that during heme breakdown, biliverdin is formed as a byproduct through heme oxygenase, whereas bilirubin is derived from biliverdin through biliverdin reductase. Bilirubin is a yellowish-coloured pigment, and biliverdin is a green-coloured pigment.

In what all conditions can bilirubin and biliverdin get raised?

In most instances, a rise in bilirubin may occur due to any problem in the liver or bile duct or due to obstruction of red blood cells. (11) An increase in biliverdin may be due to improper conversion of biliverdin to bilirubin.

How to control Bilirubin and Biliverdin levels?

Bilirubin and Biliverdin levels may be controlled by reducing the risk factors leading to liver damage. This can be done by eating healthily and avoiding smoking and alcohol consumption to help improve liver health.

About the Author

HexaHealth Care Team

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