There are two types of bilirubin formed in our bodies. They are Conjugated Bilirubin and Unconjugated Bilirubin, respectively. They differ in chemical structure, type, and also function. They are two separate products and vary in their molar weights as well. The increase in the level of bilirubin results in yellow pigmentation. Moreover, it gets deposited in the tissues. This condition is known as jaundice.
To be able to distinguish between the two, knowing their features individually is important. This shall help us to understand the functioning in a better way.
Key Takeaways
- Unconjugated bilirubin forms a waste product from haemoglobin breakdown, while conjugated bilirubin results from the liver processing unconjugated bilirubin.
- Conjugated bilirubin is water-soluble, whereas unconjugated bilirubin is not.
- Elevated levels of unconjugated bilirubin may indicate hemolytic anaemia, while high levels of conjugated bilirubin can suggest liver dysfunction.
Conjugated Bilirubin vs Unconjugated Bilirubin
Conjugated bilirubin is excreted from the liver and excreted into the bile and intestines, which can be a sign of liver disease. Unconjugated bilirubin is a fat-soluble form that is not yet processed by the liver. Elevated levels in the blood can be a sign of various conditions, such as hemolytic anaemia or Crigler-Najjar syndrome.
Conjugated Bilirubin is defined as the part or fraction of bilirubin that is conjugated with glucuronic acid. The process takes place inside the liver to form bilirubindiglucoronide. It is not present in the urine. However, it forms high plasma concentration. They can be excreted out of the body directly.
On the other hand, Unconjugated Bilirubin is part of the fraction of bilirubin that is not conjugated in the liver. It is not soluble in water and is also not present in urine. It is quite toxic to the tissues. Accumulation of Unconjugated Bilirubin leads to severe neuro disorders.
Comparison Table
| Parameters of Comparison | Conjugated Bilirubin | Unconjugated Bilirubin |
|---|---|---|
| Solubility | It is soluble in water. | It is insoluble in water. |
| Excretion | It can be excreted out of the body directly. | It can not be excreted out of the body directly. |
| Transport | Can travel through the bloodstream without any transport protein. | Can travel through the bloodstream only with transport protein. |
| Filtration | Can be filtered through kidneys. | Can not be filtered through kidneys. |
| Bile | It is present in bile. | It is not present in bile. |
What is Conjugated Bilirubin?
The maximum breakdown procedure takes place in the liver. The breakdown of cytochromes and myoglobin results in the formation of 20 percent bilirubin in our body. The process of conversion of urobilinogen to stercobilinogen takes place in the large intestine.
There is a process of deconjunction of the bilirubin. It takes place in the guts. Almost 20 percent of it is reabsorbed. From there, a specific part of urobilinogen falls into the bloodstream. It eventually gets excreted with urine as a waste product.
An increase in Conjugated Bilirubin might result in the dark color of urine. The color ranges from dark yellow to brown. It can easily pass through the kidney filter and is soluble in water. However, it is insoluble in fats as well as alcohol.
On average, 250-300 mg of bilirubin is produced every day in the body of a human being. The conjugation takes place in the liver. It is the process by which unconjugated bilirubin gets bound with glucuronic acid. The Conjugated Bilirubin formed mainly goes into the duodenum.
What is Unconjugated Bilirubin?
Unconjugated Bilirubin is formed in the reticuloendothelial cells. It can not enter the small intestine along with the bile. The maximum amount of bilirubin is formed due to the breakdown of haemoglobin. It is produced due to the degradation process of the erythrocytes. This contributes to 80 people of the total bilirubin.
It is formed due to the increased breakdown of red blood cells. When the rate is excessive, It accumulates in the bloodstream. Furthermore, it is bound to albumin. The albumin helps to bind the Unconjugated Bilirubin. Jaundice is a condition caused due to the abnormality of bilirubin. It causes yellow discolouration of the skin. Also, Unconjugated Bilirubin causes hyperbilirubinemia in children.
It is insoluble in water. However, it is indeed soluble in fats as well as alcohol. If it is contained in a great amount, it may result in serious brain damage in the long run. The term for such a condition is bilirubin encephalopathy. Sometimes there is a condition known as subicterus where yellow sclera pigmentation is formed. This takes place due to the increased formation of the bilirubin serum.
The Unconjugated Bilirubin gets converted into Conjugated Bilirubin in the liver. If it fails, it is an indication that the liver might not be working properly. Sometimes there is a blockage detected in the bile duct. In this case, excess bilirubin can be removed from our bodies.
Main Differences Between Conjugated Bilirubin and Unconjugated Bilirubin
- The most distinct way to distinguish between Conjugated Bilirubin and Unconjugated Bilirubin is their solubility. Conjugated Bilirubin is soluble in water. Whereas, Unconjugated Bilirubin is insoluble in water.
- Conjugated Bilirubin can be filtered through the kidneys. On the other hand, Unconjugated Bilirubin can not be filtered through the kidneys.
- Conjugated Bilirubin is present in bile, whereas Unconjugated Bilirubin is not present in bile.
- Conjugated Bilirubin can travel through the bloodstream without any transport protein. Whereas, Unconjugated Bilirubin can travel through the bloodstream only with transport protein.
- Conjugated Bilirubin can be excreted out of the body directly. Unconjugated Bilirubin can not be excreted out of the body directly.
- https://www.sciencedirect.com/science/article/pii/S0003269700944853
- https://www.sciencedirect.com/science/article/pii/S0165178111002228
Last Updated : 11 June, 2023
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
I found this article highly informative. I believe the distinction drawn between the two types of bilirubin was very clear and to the point.
Very informative and well written article.
I found this breakdown extremely helpful as it gave me a better understanding of bilirubin and its different types.
This article was an outstandingly in-depth explanation of the differences between Conjugated and Unconjugated Bilirubin.
I was really impressed with the depth of knowledge presented in this article.
Indeed, the detail in the article was truly impressive.
This article offers a stark and important differentiation between the two types of bilirubin.
A great article. As I see it, the crucial difference between the two types of bilirubin is the solubility. While, as said, Conjugated Bilirubin is soluble in water and can be directly excreted, Unconjugated Bilirubin is not and requires to be filtered by the kidneys.
Yes, I believe the main differentiator between the two is their chemical structure being so distinct from one another.
I found the references listed to be very useful.
This article was really well put together. I especially found the comparison table to be very helpful.
I also found the comparison table to be the most helpful part of the article.
Absolutely, the comparison table gave a great concise overview of the differences between the two types of bilirubin.