Bilirubin is the result of the breakdown of red blood cells in the body. The liver helps excrete it. Several conditions can cause high bilirubin levels in both children and adults. High bilirubin can lead to jaundice.

A person holding a newborn.Share on Pinterest
Russell Monk/Getty Images

This disorder is easily recognizable due to a yellowing of the skin and eyes.

High bilirubin levels can occur in adults, but the disorder is more common in newborns. This is because it takes some time after birth for an infant to start efficiently metabolizing bilirubin and excreting it in their stool.

The approximate normal range of bilirubin in the blood is less than 1.0 milligram per deciliter (mg/dL).

The skin normally becomes yellow once levels reach 2–3 mg/dL. Any person who experiences yellowing of the skin or eyes should see a doctor. It may be a sign of a serious condition.

The breakdown of red blood cells (RBCs) in the body produces bilirubin. The bilirubin travels to the liver, where the bile duct stores it. The body ultimately expels bilirubin through stool. Bilirubin is brown and yellow in color, and it is this pigment that makes feces brown.

The RBCs have a lifespan of around 120 days, and they renew continually. RBCs contain hemoglobin, which helps transport oxygen around the body. The process of removing iron from each cell’s hemoglobin helps the cells break down into bilirubin and other substances. The bilirubin gets to the liver with the help of albumin, a simple protein.

Once in the liver, bilirubin becomes “conjugated.” This means it is water-soluble and the body can excrete it.

Unconjugated bilirubin is toxic. Conjugated bilirubin is usually not because it can come out of the body, as long as nothing is interfering with its removal.

A high level of bilirubin in the blood is known as hyperbilirubinemia.

High bilirubin levels can cause jaundice. Jaundice makes the skin and the whites of the eyes appear yellow, due to the brown and yellow bilirubin in the blood.

A doctor can usually detect a person’s bilirubin levels through a blood test. While every laboratory may have slightly different reference ranges, the following values approximately represent normal bilirubin levels based on age.

A doctor generally considers anything above these values to be high.

AgeLevel
1 day1.4 to 8.7 mg/dL
1 day – 2 days 3.4 to 11.5 mg/dL
2 days – 5 days 1.5 to 12.0 mg/dL
Over 5 days 0.3 to 1.2 mg/dL

There are several reasons for a rise in bilirubin levels outside of the newborn period. These causes can occur before, during, or after the production of bilirubin.

There are several conditions that can cause high bilirubin levels either before reaching the liver, after leaving the liver or within the liver itself.

Before reaching the liver

Some conditions cause high bilirubin levels before it reaches the liver.

This is the pre-hepatic or the “pre-liver” phase. The cause is hemolytic anemia and the reabsorption of internal pools of blood by the body.

Hemolytic anemia occurs when too many red blood cells break down before the end of their natural life cycle.

In the liver

If the liver is not working properly, it may be unable to make bilirubin water-soluble. This may result in too much bilirubin building up in the liver. Causes for this include:

  • viruses, such as hepatitis A
  • alcoholic liver disease
  • some medicine overdoses, including acetaminophen
  • autoimmunity, where a disorder of the immune system causes it to attack the cells of the body rather than those that cause disease

After leaving the liver

Once bilirubin has left the liver, in the “post-hepatic phase,” its levels may be high because it is unable to leave the body.

This may be a result of a blockage in one of the other organs that assist excretion, such as from gallstones in the gallbladder.

Other causes may include inflammation or cancer of the gallbladder, which produces bile, or pancreatitis.

Gilbert’s syndrome

Gilbert’s syndrome is a mild form of high bilirubin. The levels go up and down because Gilbert’s syndrome slows down the process of removing it from the body.

The fluctuation is rarely enough to cause the skin to yellow, but some people may experience symptoms, such as stomach pain or fatigue.

Doctors estimate that about 1 in 3 people with Gilbert’s syndrome do not experience any symptoms at all. In fact, doctors often discover the condition with a blood test performed for some other reason.

There is a gene linked to Gilbert’s syndrome that shows family patterns of heredity. This gene codes for an enzyme that enables the liver to convert bilirubin to its conjugated form. The absence of this gene in Gilbert’s syndrome means that this enzyme does not work.

Newborns with high levels of bilirubin have a condition that doctors call neonatal hyperbilirubinemia or jaundice in neonates.

Approximately 50% of full-term infants and 80% of preterm infants have visible jaundice in the first 2 to 4 days after birth if their serum bilirubin levels are at or above 5 mg/dL

In adults, bacteria in the gut break down the conjugated bilirubin to create a by-product called urobilinogen, some of which is excreted by the kidneys as urobilin. The urobilin is also what gives urine its yellow color.

In neonates, the liver takes several days to start adequately processing bilirubin. Neonatal jaundice occurs when the liver is not quite ready to process the bilirubin and the accumulation in the blood causes certain tissues to look yellow.

The seriousness and medical significance of elevated bilirubin will depend on the cause. The age of the infant, as well as whether they were born premature, is also a factor. In a healthy infant, born at full term, bilirubin levels tend to cause concern when they exceed around 18 mg/dL.

For premature infants, the earlier the delivery occurs in the gestation period, the lower the threshold at which health professionals consider bilirubin levels to be excessive.

High bilirubin levels can be toxic to the nervous system and cause brain damage.

Most jaundice in infants is not severe, and the symptoms resolve naturally. Prolonged jaundice is more common in infants who are breastfeeding. This type of jaundice is usually not harmful but requires close monitoring.

The neonatal doctor might recommend seeing a lactation consultant among other treatments if they give a jaundice diagnosis.

Some infants receive phototherapy, where a physician exposes the baby to a special kind of blue-green light. This is a standard treatment, in which the light converts the bilirubin to a different form that the liver and kidneys can remove.

High levels of bilirubin in the blood can cause jaundice, which may cause symptoms, such as:

Because an underlying condition, such as liver disease or hemolytic anemia, may cause high bilirubin levels, a person may also experience other symptoms, including:

Blood tests can measure bilirubin levels. While there is a urine test for bilirubin, it is less accurate and often falsely positive.

If a routine urine test detects bilirubin, a doctor will look at blood serum tests to confirm the results and identify any damage to the liver.

Other tests may include:

  • further blood tests to assess liver function and test for hepatitis, if indicated
  • a physical exam, where a doctor may feel the abdominal area to see if the liver is swollen or tender
  • imaging tests to visualize the liver, which might include an ultrasound, computerized X-ray with a CT scan, or high-powered images with an MRI scan
  • an endoscopy to look at the ducts in which the bile travels to the gut
  • a liver biopsy, while uncommon, involves a small sample of liver tissue evaluated at a lab

Treatment depends on the underlying cause of the high bilirubin. If the cause is known, a person might remove bilirubin through treatment or lifestyle changes, such as avoiding alcohol.

Infants may need phototherapy, which helps the liver break down bilirubin using a special type of blue-green light, to treat their high bilirubin levels.

An exchange transfusion, which involves removing the blood through a thin plastic tube and replacing it with blood from a suitable donor, may also be necessary.

Here are some common questions about high bilirubin levels.

Is high bilirubin life threatening?

High levels of bilirubin are often a symptom of another underlying health condition, which can range in terms of severity and prognosis.

In infants, high levels of bilirubin in the blood can lead to serious complications if left untreated, including kernicterus, a condition that can lead to brain damage, intellectual disabilities, and issues with hearing or vision.

Who is at a higher risk for elevated bilirubin levels?

According to a 2022 review, newborns and older adults are at a higher risk for developing jaundice caused by elevated bilirubin levels. However, the prevalence of specific causes of elevated bilirubin can also vary depending on several factors, including age and sex.

What does it mean to have elevated bilirubin with normal liver enzymes?

If a person has normal levels of liver enzymes, it may mean that there is another condition contributing to the elevated bilirubin levels besides liver disease.

However, keep in mind that a person can still have liver damage with normal liver enzyme levels, so it is best to talk to a medical professional to determine the cause and best course of treatment.