Conjugated Bilirubin

Conjugated bilirubin is formed by the breakdown of hemoglobin in the red blood cells. The liver converts this bilirubin into direct bilirubin, which can then be released into the intestine by the gallbladder for elimination. Total bilirubin levels are therefore indicative of both the destruction of red blood cells and the proper functioning of the liver, gallbladder, and bile ducts.


Higher than normal levels of bilirubin may indicate different types of liver problems. Occasionally, higher bilirubin levels may indicate an increased rate of destruction of red blood cells (hemolysis).


Receive all our future posts instantly in your inbox. Enter your email to enroll.

Also Known As:  Total BilirubinTBILNeonatal BilirubinDirect BilirubinConjugated BilirubinIndirect BilirubinUnconjugated Bilirubin, TB

Test Panel: Total Bilirubin, Conjagated Bilirubin, Unconjugated Bilirubin, ALT, AST, ALP, Total Protein, Albumin, Globulin, A/G ratio, GGT,

Why Get Tested :

  • or the diagnosis of jaundice.
  • To differentiate different types of jaundice.
  • For the follow-up of a patient with treatment.
  • To assess the progress of the disease.
  • This test is done to evaluate the liver functions.
  • This is done in a patient with hemolytic anemia in adults.
  • It is also done to evaluate the hemolytic anemia in the newborn.

When to Get Tested:

Your doctor may order a bilirubin test if you:

  • Show signs of jaundice
  • Have anemia, or low red blood cells
  • Might be having a toxic reaction to drugs
  • Have a history of heavy drinking
  • Have been exposed to hepatitis viruses
  • Have cirrhosis

You might also have your bilirubin tested if you have symptoms like:

  • Dark urine
  • Nausea and vomiting
  • Abdominal pain or abdominal swelling
  • Clay-colored stools
  • Fatigue

When Bilirubin Test Orderd:

A health practitioner usually orders a bilirubin test in conjunction with other laboratory tests (alkaline phosphataseASTALT) when someone shows signs of abnormal liver function. A bilirubin level may be ordered when a person:

Other symptoms that may be present include:

  • Dark, amber-colored urine
  • Nausea/vomiting
  • Abdominal pain and/or swelling
  • Fatigue and general malaise that often accompany chronic liver disease

Measuring and monitoring bilirubin in newborns with jaundice is considered standard medical care.

Tests for bilirubin may also be ordered when someone is suspected of having (or known to have) hemolytic anemia as a cause of anemia. In this case, it is often ordered along with other tests used to evaluate hemolysis, such as complete blood countreticulocyte count, haptoglobin, and LDH.

Sample Required

  1. This test is done in the serum of the patient.
  2. The random sample can be taken and no need for a fasting sample.
  3. From infants, the blood may be collected from the heel.
  4. The sample is stable at 4 °C for 3 days and protects it from the light.

Precautions for Sample :

  1. Avoid hemolysis.
  2. Avoid shaking of the tube that may lead to inaccurate results.
  3. Do not expose the tube to light. Exposure to light like the sun or even artificial light may decrease the value.
  4. If there is a delay in the test then keep the sample away from the light and refrigerate it.

Normal Values:

  1. Total bilirubin  = 0.3 to1.0 mg/dL or 5.1 to 17.0 mmol/L
  2. Direct bilirubin   =  0.1 to 0.3 mg/dL or 1.0 to 5.1 mmol/L
  3. Indirect bilirubin (total bilirubin – direct bilirubin level) = 0.2–0.7 mg/dL

Raised level of direct bilirubin is seen in:

  1. Gallstones.
  2. Gallbladder tumors.
  3. Inflammatory scarring or obstruction of extrahepatic ducts.
  4. Extensive liver metastasis.
  5. Dubin-Johnson syndrome.
  6. Rotor syndrome.
  7. Drugs may cause cholestasis.

Table showing the Different type of Jaundice and their causes

Type of JaundiceCausesPathophysiology
Unconjugated hyperbilirubinemiaExtravascular hemolysisHeme is converted to unconjugated bilirubin
 Right heart failure and CirrhosisThere is a defect in the delivery of unconjugated bilirubin to liver
 Hypothyroidism and Crigler-Najjar syndromeThere is a defect in the conjugation of bilirubin in the hepatocytes
 Drugs like Rifampicin  and Gilbert syndromeThere is a defect in the uptake of unconjugated bilirubin into hepatocytes
Conjugated hyperbilirubinemiaMechanical obstruction by tumors, stones or strictures, and primary biliary cirrhosisThere is a defect in the flow of conjugated bilirubin through canaliculi and bile ducts. Called cholestatic jaundice.
 Drugs like estrogen and cyclosporineDubin-Johnson syndromePregnancyThere is a defect in the transmembrane secretion of conjugated bilirubin into the canaliculus. This is also called hepatocellular jaundice 
 SepsisLike above

Related Articles:

RSS Error: is invalid XML, likely due to invalid characters. XML error: Invalid document end at line 52, column 4

Possible References Used

1 comment on Conjugated Bilirubin

Leave a Reply

Your email address will not be published.