What is a bilirubin blood test?
Bilirubin is a yellow pigment that is in everyone’s blood and stool. Sometimes
the liver cannot process the bilirubin in the body because of excess bilirubin,
an obstruction, or an inflamed liver. When your body has too much bilirubin,
your skin and the whites of your eyes will start to yellow. This condition is
Bilirubin is made in the body when old red blood cells are broken down. The
breakdown of old cells is a normal, healthy process. After circulating in your
blood, bilirubin then travels to your liver. In the liver, bilirubin is
excreted into the bile duct and stored in your gallbladder. Eventually, the
bilirubin is released into the small intestine as bile to help digest fats and
ultimately excreted with your stool.
Bilirubin attached to sugar is called “direct” or “conjugated” bilirubin,
and bilirubin without sugar is called “indirect” or “unconjugated” bilirubin.
All the bilirubin in your blood together is called “total” bilirubin.
A bilirubin blood test will get an accurate count of all three bilirubin
levels in your blood: direct, indirect, and total.
Common reasons to test for bilirubin
If bilirubin is not being attached to sugars (conjugated) in the liver or is
not being adequately removed from the blood, it can mean that there is damage
to your liver. Testing for bilirubin in the blood is therefore a good
test of damage to your liver.
Newborn infants often mild jaundice, which can either be
due to normal changes in the metabolism of bilirubin or can be the first signs
of a medical problem. If the level at birth is too high, the infant’s bilirubin
in the blood may be tested several times in the first few days of an infant’s
life to check that the liver is starting to work properly. Jaundice in a
newborn can be very serious and life threatening if left untreated.
Other reasons for high bilirubin levels could be that more red blood cells
are being destroyed than normal. This is called hemolysis.
Sometimes bilirubin is measured as part of a “panel” of tests. Often, the liver is
evaluated with a group of tests that include:
- alanine transaminase
- asparate transaminase
- alkaline phosphatase
- total protein
How is the bilirubin blood test performed?
A small amount of your blood is needed to perform this test. The blood
sample is obtained through venipuncture, where a needle is inserted into a vein
through the skin in your arm or hand, and a small amount of blood comes out
through the needle into tubing and is stored in a test tube.
How do I prepare for the bilirubin blood test?
For this test, you will need to not eat or drink anything other than water
for four hours before you have the test performed. You can drink your usual
amount of water before going to the laboratory or collection site.
You may have to stop taking certain medications before the test is
performed, but only if your doctor tells you to do this. Examples of drugs that
can affect bilirubin levels include antibiotics like penicillin G, sedatives
like phenobarbital, diuretics like furosemide, and asthma medications like
theophylline. However, this is not a complete list, and there are many drugs
that can influence bilirubin levels. Talk to your doctor before your test to
see if you should stop or continue taking medication.
What are the risks of the bilirubin blood test?
When the blood is collected, you may feel some moderate pain or a mild
pinching sensation, though this is usually very short in duration and very
slight. After the needle is taken out, you may feel a throbbing sensation, and
you will be instructed to apply pressure to the site where the needle entered
your skin. A bandage will be applied that needs to remain in place typically
for 10 to 20 minutes, and you should avoid using that arm for heavy lifting for
the rest of the day.
There are some very rare risks to taking a blood sample:
- lightheadedness or fainting
- hematoma, a bruise where blood accumulates under the
- infection, usually prevented by the skin being cleaned
before the needle is inserted
- excessive bleeding, or bleeding for a long period
afterward may indicate a more serious bleeding condition and should be
reported to your doctor.
What is a normal result for the bilirubin blood test?
In an older child or adult, normal values of direct bilirubin are from 0
to 0.4 milligrams per deciliter (mg/dL). Normal values of total bilirubin
are from 0.3
to 1.0 mg/dL.
In a newborn, higher bilirubin is normal due to the stress of birth. Normal
bilirubin in a newborn would be under 5 mg/dL, but many
newborns have some kind of jaundice and bilirubin levels above 5 mg/dL.
Causes of abnormal results
Your doctor may want to perform further blood tests or an ultrasound if high
levels of bilirubin are detected in your blood. In an adult, high bilirubin may
be due to problems with the liver, bile ducts, or gallbladder. Examples
- drug toxicity
- liver diseases like hepatitis
- Gilbert’s disease, a genetic disease affecting some
- Cirrhosis, scarring of the liver
- biliary stricture, part of the bile duct is too narrow
to allow fluid to pass
- cancer of the gallbladder or pancreas
Another cause of high bilirubin may be due to problems in the blood instead
of problems in the liver. Blood cells breaking down too fast can be caused by:
This occurs when too many blood cells are being destroyed from an autoimmune
disease, genetic defect, drug toxicity, or infection, and the liver is unable
to metabolize the amount of bilirubin in the body
This occurs when your immune system attacks blood that was given to you
through a transfusion.
In an infant, high bilirubin and jaundice can be very dangerous, and may be
caused by several factors. There are three common types:
- physiological jaundice: at 2-4 days after birth, caused
by a brief delay in the functioning of the liver, usually not serious
- breast feeding jaundice: during first week of life, caused
by a baby not nursing well or low milk supply in the mother
- breast milk jaundice: after 2-3 weeks of life, caused
by the processing of some substances in breast milk
All of these can be easily treated and are usually harmless if treated. Some
more serious conditions that cause high bilirubin and jaundice in an infant:
- abnormal blood cell shapes, such as sickle cell anemia
- blood type mismatch between infant and mother, leading
to breakdown of the baby’s red blood cells, called erythroblastosis
- lack of certain important proteins due to genetic
- bleeding in the scalp due to a difficult delivery
- high levels of red blood cells due to small size,
In both adults and children, symptoms related to high bilirubin involve
jaundice, a yellowing of the skin or eyes, fatigue, itchy skin, dark urine, and
What happens after a bilirubin blood test
If your blood tests show abnormally high levels of
bilirubin, your doctor may order more tests to determine the underlying cause.
Once your doctor has determined a cause of high bilirubin levels, you may take
more bilirubin blood tests to monitor the effectiveness of your treatment. If
your doctor thinks your liver or gallbladder may be working inappropriately,
they may order imaging tests to ensure there are no structural abnormalities.