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Bilirubin

Written by Ada’s Medical Knowledge Team

Updated on

Bilirubin is a yellowish substance that is formed by the body when red blood cells are broken down.[1] Bilirubin is toxic to the body, so under usual circumstances, it gets processed by the liver and then leaves the body through the stools. When this process doesn’t work well due to conditions of the blood, the liver or the gallbladder, it can cause jaundice. Jaundice means that the skin and the whites of the eyes turn yellow.

As the liver plays a big part in the excretion of bilirubin, it’s often said that your liver health can be checked by the amount of bilirubin in your blood. Bilirubin in urine can also indicate the presence of a serious liver problem.

If you think your bilirubin levels might be out of the normal range, try using the free Ada app to find out more about your symptoms.

What is bilirubin?

Bilirubin is a pigmented substance that provides the bile, stools and in lesser amounts the urine with their brown-yellow color. In certain cases, it can also cause the whites of the eyes and the skin to turn yellow (also known as jaundice).[2]

Bilirubin is formed as a by-product during the breakdown process of red blood cells. During our lifespan, new red blood cells are continuously being produced by the bone marrow and old red blood cells are broken down. While breaking down a specific part of the red blood cells, called hemoglobin, bilirubin is formed.

This bilirubin is toxic, but our body has mechanisms to excrete this substance. Once formed, bilirubin gets processed by the liver, excreted in the bile and then goes on through the intestines to finally leave the body in the stools.[1]

This is a normal process, but in some cases the amount of bilirubin in the blood can increase, causing jaundice. With jaundice, the whites of the eyes and the skin turn yellow. Conditions in the liver or the gallbladder such as liver cirrhosis, hepatitis (inflammation of the liver) and obstructions of the gallbladder can cause problems in the normal excretion of bilirubin.[1]

Another frequent issue with bilirubin occurs in newborns. This is called neonatal jaundice. Before birth, the mother’s liver takes care of the bilirubin excretion. After birth, the baby’s liver should take over. In some cases, the liver hasn’t fully developed yet and can’t excrete the bilirubin, causing jaundice. This is the most common cause why newborns get admitted to the hospital. Although neonatal jaundice isn’t always a serious condition, it can cause serious complications and should always be checked by a doctor or a midwife.[2]

What is conjugated and unconjugated bilirubin?

There are a few types of bilirubin, depending on whether or not the bilirubin has passed through the liver.

  • Conjugated bilirubin (also called direct bilirubin)
  • Unconjugated bilirubin (also called indirect bilirubin)
  • Total bilirubin: the total amount of bilirubin that can be found in the bloodstream

Unconjugated bilirubin is bilirubin that hasn’t been processed by the liver yet. This bilirubin is created when hemoglobin, a substance in the red blood cells, is broken down. The unconjugated bilirubin then binds to a protein in the blood and gets transported to the liver.

Once arrived in the liver, the bilirubin binds to an acid present in the liver and later on gets excreted. This bilirubin is called conjugated bilirubin.[3]

What is Gilbert’s syndrome?

Gilbert’s syndrome is a condition in which bilirubin levels in the blood are elevated even when the person doesn’t have any liver damage or blood conditions. Episodes of jaundice can occur especially when the body is under stress.

With Gilbert’s syndrome, unconjugated bilirubin is slower to convert into conjugated bilirubin and stays in the blood for longer. The condition is usually genetic and can therefore be inherited.

Symptoms often first appear in youth, but can present at any age. Men are more commonly affected than women. With this condition, jaundice usually occurs in episodes which resolve on their own.

However, since Gilbert’s syndrome can also alter the effect of certain medications, a visit to the doctor is still recommended to confirm the diagnosis and rule out other causes of jaundice.

What is a bilirubin nomogram?

As neonatal jaundice is one of the most common disorders in newborns, the bilirubin nomogram was created. It’s a chart that doctors use to determine the level of risk a newborn has to have too much bilirubin present in the blood.[2]

The nomogram takes the baby’s age in hours into account, as well as the amount of bilirubin in the blood. Apart from that, there are also a few risk factors (see neonatal jaundice) that are taken into account to determine whether or not the newborn is at risk for developing jaundice.

Because of the bilirubin nomogram, doctors are able to determine how high the risk is for the baby to develop neonatal jaundice. By being able to react quickly when a baby is at high risk, serious complications may be avoided.

How to lower bilirubin?

Bilirubin can be checked in the urine or through bloodwork. When having bloodwork done, the normal range for total bilirubin is 3.4 to 20.0 micromol/L (0.2 to 1.2 mg/dL).[4]

Having low bilirubin usually doesn’t cause any symptoms. It can be caused by consuming a lot of caffeine or taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin.

People with too much bilirubin in their blood should seek medical advice. In general, bilirubin can be lowered by controlling the underlying condition that causes the excessive amount of bilirubin in the blood. Apart from that, it’s important to maintain a healthy diet and to avoid the consumption of alcohol.[4]

Feeling unwell? Get a symptom assessment with the free Ada app.

Frequently asked questions

Q: How is bilirubin defined? Bilirubin is an orange-yellowish pigment that is formed by the breakdown of hemoglobin in red blood cells. It gets excreted by the liver into the bile. It can be found in blood and urine, especially with certain conditions such as liver cirrhosis, hepatitis and gallstones.

Q: What does bilirubin do? A: Bilirubin is a by-product of the natural breakdown of red blood cells. It normally passes through the liver and gets excreted from the body.

Q: When do I need to seek medical help? When the skin or the white of the eyes starts turning yellow, it’s an indication that there is too much bilirubin present in the blood. This can be an indication that there is a problem with the liver, gallbladder, or the blood.


  1. NHS (2022). Bilirubin Total. Accessed March 23, 2022.

  2. CDC (2020). What are Jaundice and Kernicterus?. Accessed March 23, 2022.

  3. Kalakonda A, et. al. (2021). Physiology, Bilirubin. Accessed March 23, 2022.

  4. NHS (2021). Gilbert's syndrome. Accessed March 23, 2022.

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