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Bilirubin test

Total serum bilirubin

Bilirubin test is carried out by analyzing bilirubin in the blood. It can be used to diagnose various liver diseases including jaundice.

A bilirubin test refers to a test that is used to estimate the concentration of the bilirubin in the blood or detect its presence in the urine. High levels of bilirubin in your bloodstream, may be caused by many health problems such as jaundice, cirrhosis, hepatitis, hemolytic Anemia, and gallbladder diseases. What is the bilirubin test procedure and precaution, and what does the result mean?


What is bilirubin?

Bilirubin is a dark yellowish substance produced during Hemoglobin breakdown (the protein of the red blood cells responsible for carrying oxygen). Red blood cells breakdown is a normal body process that occurs after ending the life of these cells. Bilirubin is considered as a waste product seen in the bile – the fluid of your liver -. It is involved in fat digestion. After circulating in your bloodstream, it will transfer to the liver, where its chemical composition changes and is mixed with bile. Then most bilirubin quantities are eliminated through the stool.


Types of bilirubin

Bilirubin has several types. The bilirubins main types are:

Unconjugated bilirubin (indirect bilirubin)

This type of bilirubin is produced by red blood cell breakdown. It transfers through the bloodstream into the liver.

Conjugated bilirubin (direct bilirubin)

When the unconjugated type reaches the liver, it will undergo conjugation and change its chemical composition by attaching it with glucuronic acid (an acid derived from glucose). This type is known as conjugated or direct. After that, it will move into the intestine to be excreted through the stool.


What is a bilirubin test?

Bilirubin tests involve total serum bilirubin with a blood sample and urinary bilirubin. Total serum bilirubin refers to the measurement of both types: the conjugated type and the unconjugated one.

Delta bilirubin is the other less common bilirubin measurement. It is only produced in case of impaired elimination of the conjugated type from the liver. This may occur in patients who have a bile duct obstruction. This type of conjugated bilirubin is linked to albumin. It may remain in the bloodstream for a prolonged period.

Higher levels of bilirubin may refer to many health issues. It may indicate an unusual or higher rate of red blood cells breakdown or liver disease that affects the liver’s ability to break down waste properly, so bilirubin accumulates in the blood. The other possible problem may be a defect somewhere along the pathway of bilirubin out of your body.


Purpose of bilirubin test

Liver disease symptoms
Abdominal pain and swelling are one of liver disease symptoms.

This test is usually ordered and other blood or urine tests, such as a liver panel, comprehensive metabolic panel, or urinalysis. Measuring bilirubin levels in the blood or the urine is used to diagnose many health problems such as jaundice (a condition that causes yellow eyes and skin) and hepatitis, cirrhosis, and hemolytic Anemia, and gallbladder diseases.

In those who have liver disease, repeated bilirubin testing regularly helps to follow up the infection, liver health, and treatment effectiveness.

jaundice in infants

Jaundice in infants
Bilirubin test for newborns

High bilirubin levels are more common in newborns because the liver usually needs some more time after birth to metabolize bilirubin efficiently and eliminate it. Jaundice in newborns is generally harmless and can disappear within a few weeks. Still, very high and prolonged levels may cause some complications if left untreated, such as kernicterus, which is a type of brain damage.

This test is commonly done for newborns during their first few days and if they have any jaundice in newborn symptoms. There are 3 main types of jaundice in infants:

  • Physiological jaundice

It occurs two to four days after birth due to a brief delay in liver functioning. It is usually not dangerous.

  • Breastfeeding jaundice

This type refers to jaundice that appears during the first week after birth due to the mother’s inadequate nursing or low milk supply.

  • Breast milk jaundice

Affect infants two to three weeks after birth due to some substances processing in breast milk.


What does this test measure?

The bilirubin blood test determines its amount in the blood. It will measure how many milligrams of bilirubin is found per one deciliter of blood. Mainly, there are two forms of bilirubin in the blood.

  • Unconjugated bilirubin (indirect bilirubin).
  • Conjugated bilirubin (direct bilirubin).

Once bilirubin becomes conjugated in the liver, it will be a water-soluble waste product and can be excreted. Total bilirubin serum measures both of them. Unconjugated bilirubin is nontoxic, while conjugated type usually is not.

Neonatal bilirubin is commonly measured in newborns. High levels of total bilirubin mainly refer to an increase in unconjugated type levels. Usually, their livers need a few days to perform the conjugation and clearance processes. About one week after birth, bilirubin levels will reach normal levels.

The urinary bilirubin test detects whether it is present in the urine or not.

Bilirubin test procedure

Total serum bilirubin
Bilirubin blood test procedure

A Bilirubin Blood test needs to withdraw a blood sample from your vein in your arm, while a urine test will require a urine sample.

Before the test

When you undergo this test, your doctor will tell you to avoid eating or drinking for 4 hours before the test. In addition to that, many medications may interfere with the test results, so you have to tell your healthcare provider about all medicines that you use before taking the sample. He may ask you to stop some medications, but do not stop any of your medication without your doctor’s consultation.

Antibiotics such as penicillin G, sedatives like phenobarbital, diuretics like furosemide, non-steroidal anti-inflammatory drugs (NSAIDs), and asthma medications like theophylline may affect bilirubin levels test.

During the test

During this test, your healthcare provider will use a small needle to draw a blood sample from the vein in your arm. You may feel a slight sting sensation during the entry of the hand. This will not take more than a few minutes. For infants, a small blood sample is taken from their heels instead of their arms.

For the urinary bilirubin test, you will be asked to collect a small sample of urine in a special container. Your healthcare specialist will also give you certain instructions about how to collect a sterile urine sample by the “clean-catch” method. These instructions include:

  • Wash your hands before taking the sample.
  • Clean the genital area.
  • Urination of a small amount in the toilet before taking the sample.

After the test

If you have been asked not to eat or drink before the test, you can bring a snack with you to eat after taking the sample. No special precautions follow the test, and you can resume your normal activities after the test.

You may feel a little pain or a bruising sensation at the site of needle entry. Do not worry, and this will go away quickly. Ask your doctor if you notice excessive bleeding or infection signs. There are also no special instructions to follow after a urinary bilirubin test.

Read more: cerebrospinal fluid analysis


Bilirubin normal range

total serum bilirubin

In adults or older children, the normal bilirubin range of conjugated bilirubin (direct) is from 0 – 0.4 milligrams per deciliter, while the total bilirubin normal range is from 0.3 – 1.0 mg\dl.

The value of the unconjugated bilirubin (indirect) in the bloodstream is the total bilirubin minus conjugated bilirubin. The bilirubin normal range is not universal. Average reference values may vary from lab to lab.

In newborns, higher levels of bilirubin are expected because of birth stress. The normal level of indirect bilirubin would be under 5.2 mg\dl. Many babies may have jaundice in newborns (bilirubin level more than 5) within a few days after birth.

Urinary bilirubin test

This test result may be positive refer to bilirubin detection in the urine or negative, which means that bilirubin is not detected. The result will be negative in healthy people with normal bilirubin functions.

Lower bilirubin levels than normal levels are not a health problem.

When is the test ordered?

This test may be ordered as well as other laboratory tests ( usually including ALP and ALT) as a group called liver function tests.

These tests may be required in some cases, including:

  • any signs of jaundice.
  • drug toxicity.
  • Taking drugs metabolized by the liver.
  • Using medications affects liver functions.
  • Patients with hepatitis viruses.
  • Anemia or low red blood cells count.
  • History of drinking alcohol.
  • Cirrhosis patients.
  • Follow up on an existing liver disorder.

Other signs or symptoms of liver disease may include:

  • Dark yellowish-orange urine.
  • Itching.
  • Nausea and vomiting.
  • General fatigue.
  • Abdominal swelling or pain.
  • Pale stool.
If the bilirubin levels range from 2 to 3 mg\dl, the skin will turn yellow.

Causes of abnormal results

If high levels are detected, your healthcare provider may want to perform additional tests and an ultrasound. In adults, high levels may be due to a health problem in the liver, gallbladder, or bile ducts.

Before reaching the liver

Some health conditions may cause elevated bilirubin levels in the blood before reaching the liver. This is called the pre-hepatic phase.

Hemolytic Anemia is the cause of high unconjugated bilirubin in this phase. It refers to the breakdown of too many red blood cells before reaching the end of their natural life cycle.

In the liver

If the liver does not work correctly, it will not be able to produce the conjugated bilirubin (water-soluble product). This will lead to the accumulation of too much bilirubin in the liver. This may result from many reasons, including:

  • Hepatic viruses, such as hepatitis A.
  • Alcoholic disorders.
  • Overdose of some medicines.
  • Autoimmune disorders (cause the immune system to attack the body cells instead of microbes).

After leaving the liver

When the bilirubin leaves the liver, its level may be higher than normal when it can not leave the body. This condition may result from the blockage of one organ that is responsible for its elimination, such as gallstones in the gallbladder. This is known as the post-hepatic phase.

Other possible causes include:

  • Gallbladder inflammation or cancer.
  • Pancreatitis.
Very hard exercise such as running a marathon may increase bilirubin levels.

Risks of bilirubin blood test

Bilirubin test procedure
Bilirubin blood test

After taking the sample, you may feel a little pain or pinching sensation. You will be جadvised to apply pressure on the place of the needle entry. A bandage will also be placed on the site.

Keep the bandage on the site of the needle for at least 10 to 20 minutes. You may also have to avoid using this arm for heavy lifting for the rest of this day. Some rare complications may follow the process of taking a sample. These include:

  • Excessive bleeding.
  • Prolonged bleeding.
  • Infection, so the skin must be cleaned before needle insertion.
  • Blood accumulation under the skin.
  • Dizziness and loss of consciousness.

Is there anything else you need to know about the bilirubin test?

Normally, bilirubin should not be found in the urine sample, but in some cases, when it’s level increases in the blood, conjugated bilirubin, which is water-soluble, may be excreted from the body in the urine. Positive results of the urine sample usually refer to liver or bile duct blockage, hepatitis, or other liver diseases.

Although high levels of unconjugated bilirubin may be dangerous for brain development in newborns (up to 2 – 4 weeks after birth), it does not have the same threat in older children and adults. This is because, in older people, the blood-brain barrier is well developed and prevents the bilirubin from crossing into the brain.

High bilirubin levels in children or adults mainly refer to an underlying disease that must be diagnosed and treated.

Are there some people at higher risk of high bilirubin levels?

Certain inherited conditions may increase bilirubin concentration. These conditions include:

  • Gilbert’s syndrome.
  • Dubin-johnson syndrome.
  • Rotor’s syndrome.
  • Crigler-Najjar syndrome.

Crigler-Najjar is the rarest of them, but it is the most serious one. The other three conditions are mild and long-term cases.


Gilbert’s syndrome

Gilbert’s syndrome is a mild condition associated with high levels of bilirubin (hyperbilirubinemia). Removing bilirubin from the body is slowed down, so its levels go up and down. Mostly, this fluctuation will not cause your skin to turn yellow, but it may cause other symptoms such as fatigue or stomach pain.

Gilbert’s syndrome is caused by changes in the gene known as UGT1A1 that is responsible for making the conjugated bilirubin go out of the body. This syndrome may have different inheritance patterns.


Jaundice in newborn

Hyperbilirubinemia treatment in newborn
Hyperbilirubinemia (jaundice in neonates) treatment

Neonatal hyperbilirubinemia refers to high levels of bilirubin in newborns. It is also called jaundice in newborns. Almost half of all babies have visible jaundice in neonates at the first week after birth, according to the Merck manual.

Normally, bacteria in the adult gut break down the conjugated bilirubin and produce urobilin that is excreted in faeces. On the other side, the liver needs several days to start bilirubin processing adequately.

Neonatal hyperbilirubinemia seriousness depends on many factors, including:

  • Condition cause.
  • Infant age.
  • Whether the baby was born premature or full term.

In full-term babies, bilirubin levels will cause danger if it exceeds 18 mg\dl. For premature infants, the earlier the delivery occurs during the pregnancy period, the lower the threshold at which bilirubin levels is considered to be excessive.

hyperbilirubinemia may affect the nerves and cause brain damage. However, most jaundice in neonates is not severe and its symptoms can be treated naturally. Prolonged jaundice is more common in breastfeeding infants. This type is usually not harmful; it only needs close monitoring.

Some healthcare providers advise seeing a lactation consultant along with other treatments. Some infants may be treated with phototherapy using a certain type of blue-green light. This light may convert the bilirubin into a different form that the liver and the kidneys can remove.


What will happen after a bilirubin blood test?

Sometimes, bilirubin levels are measured as a part of a group of tests to evaluate the health of the liver. These tests include

  • Alanine transaminase.
  • Aspartate aminotransferase.
  • Alkaline phosphatase.
  • Albumin.
  • Total protein.

If your results show high bilirubin levels, your healthcare specialist will order additional tests to detect the exact cause of hyperbilirubinemia. Once the cause has been determined, you will start the treatment and you will need more bilirubin blood tests to follow up on the treatment effectiveness.

If the liver or the gallbladder problems are the cause of hyperbilirubinemia. You will have to undergo imaging tests to ensure no structural abnormalities in addition to that your healthcare provider may require a biopsy to take a sample from the tissue in the liver to examine it.


A bilirubin test is a way to measure bilirubin levels in the blood or the urine to estimate the health of your liver, gallbladder, and red blood cells. This test helps diagnose many problems such as jaundice, hepatitis, cirrhosis, gallbladder diseases, and hemolytic Anemia. It is also used to detect jaundice in neonates.

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