Normal Bilirubin Levels


What is bilirubin?

Bilirubin is an orangey-yellow pigment that is present in the blood and its levels can be checked by bilirubin testing. The regular breakdown of the red blood cells naturally releases a byproduct which is known as bilirubin. It is normally carried in the blood and passes from the liver. Excessive levels of bilirubin in the blood may be considered as an indication of liver disease or damage.

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The bilirubin that has not passed onto the liver is called indirect bilirubin. After it reaches the liver, it sticks to some kinds of sugars and results in the creation of direct bilirubin.

The direct bilirubin is secreted into bile and transferred to the gall bladder before being finally eliminated as a part of stool. Increased levels of direct or indirect bilirubin are general indicators of different types of liver abnormalities. On certain occasions, increased bilirubin levels can also point to excessive rate of damage to the red blood cells. Read information about bilirubin in urine.

Bilirubin test

Bilirubin testing is done in conjunction with a number of other tests for the following reasons:

  • To verify the clogging of the bile ducts in the liver
  • To check for the presence of jaundice, as increased levels of bilirubin can result in increased yellowing of the skin as well as the whites of the eyes
  • To check and follow the effectiveness of a treatment plan
  • To detect or monitor the presence or progression of liver diseases such as hepatitis
  • To detect if there is any destruction of the red blood cells
  • To check and verify the suspected levels of drug toxicity

The various other tests that may be carried out along with bilirubin testing include the following:

  • Alanine transaminase or ALT is an enzyme that is mainly present in the liver cells and assists in the metabolism of proteins. The normal levels of ALT are generally low, but any damage to the liver can lead to the release of ALT into the blood leading to increased levels of ALT in the blood.
  • Aspartate transaminase or AST is present in increased concentrations in the cells of the liver. It is an enzyme that plays an important part in the metabolism of alanine which is an amino acid. Increased levels of AST, generally indicate the presence of liver disease or damage
  • Alkaline phosphatase or ALP is another enzyme that is present in increased concentrations in the bile ducts, the liver as well some tissues of the body. Higher levels of ALP indicates liver damage
  • Albumin is a protein that is manufactured by the liver. The levels of total protein and albumin indicate the effectiveness of the liver in the production of the various proteins that assist in countering the forces of various infections. Decreased levels of albumin indicate liver disease.
  • A complete blood count or CBC can indicate the presence of liver irregularities or other kinds of blood cells damage.

Bilirubin testing – How is it done ?

In order to conduct a bilirubin blood test, the blood is drawn out from a vein in the arm of the patient. There are no untoward risks involved in this. However, there may be some soreness and discomfort of the area, where the needle has been inserted to draw out the blood.

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Once the needle is removed, a small bandage or wire gauze is place at the affected site and the patient is asked to put pressure on it for a few minutes to stop any unwanted bleeding.

The collected blood sample can then be sent to a laboratory for testing. Such laboratories may be onsite or off site, and depending on their location, the test may yield results within hours or several days.

Normal bilirubin levels

  • The total bilirubin consists of both direct and indirect bilirubin. The normal results of a regular bilirubin test that checks for the total bilirubin levels fall in the range of 0.1 to 1 mg/dL.
  • The normal range for direct bilirubin falls within 0 to 0.3 mg/dL
  • The abbreviation mg/dL stands for milligram per deciliter.
  • The calculation of indirect bilirubin is done by subtracting the direct bilirubin from the complete or total bilirubin results.
  • Most of the results are typical for the male adults, but may vary by a slight degree from one laboratory to another.
  • In case of women and children, the normal results can become affected by rigorous exercise, medications and intake of certain foods and hence tend to be slightly different. Hence it is very important to inform the doctor of the food intake, current medications as well as recent physical activities to get the optimum bilirubin results.
  • Bilirubin test results that show elevated levels of direct bilirubin indicate malfunction or damage of the liver, which prevents the liver from efficiently carrying out its tasks. For example, a bile duct may be blocked resulting in higher levels of direct bilirubin.
  • Lower than normal levels of indirect bilirubin are not serious in nature but can be considered as an indicator of many other problems such as Gilbert’s syndrome; which points to deficiencies of an enzyme that assists in the breakdown of bilirubin. In such cases further tests may be required to ascertain the presence of any medical condition.
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