- This test is done on the serum of the patient.
- The random sample can be taken and no need for a fasting sample.
- From infants, the blood may be collected from the heel.
- The sample is stable at 4 °C for 3 days and protects it from the light.
- Avoid hemolysis.
- Avoid shaking of the tube that may lead to inaccurate results.
- Do not expose the tube to light. Exposure to light like the sun or even artificial light may decrease the value.
- If there is a delay in the test then keep the sample away from the light and refrigerate it.
Purpose of the test (Indications)
- For 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.
- Raised Bilirubin is the indicator of liver dysfunction.
- Basically, this is the end product of Hemoglobin metabolism.
- Bilirubin is one component of bile which is transported from liver and stored in the gallbladder and from there delivered to the intestine.
- Bile is formed in the liver and it consists of Bile salts, phospholipids, cholesterol, bicarbonate, bilirubin and water.
- Further metabolism of bilirubin takes place in the intestine.
- Most of it is metabolized in the intestine and excreted in feces.
- The increased amount of the bilirubin causes the yellow color of the skin and conjunctiva ( Jaundice ).
- The bilirubin which is not conjugated to the liver, attach to albumin (carrying protein )is called Indirect bilirubin.
- The bilirubin conjugate with the glucuronic acid. This process takes place in the liver and gives rise to conjugated or direct bilirubin. Now conjugated bilirubin is no more bound to protein.
- Direct bilirubin + Indirect bilirubin = Total bilirubin.
- Indirect bilirubin is calculated as follows:
- Indirect bilirubin = Total bilirubin – direct bilirubin
- Hemoglobin from RBC is released and form Heme and Globin.
- Heme is metabolized to Biliverdin and this is transformed into bilirubin.
- Jaundice appears when the bilirubin level is above 2.5 mg/dl.
- In the newborn when the liver can not conjugate bilirubin and if the level increases then this indirect bilirubin can cross the blood-brain barrier and leads to toxic injury to the brain and called Kernicterus.
- If bilirubin level exceeds 15 mg/dl then immediately start the treatment to avoid the brain damage.
- While physiologic jaundice appears after 3 to 4 days and subsidies itself.
Normal adult values
- Total bilirubin = 0.3 to 1.0 mg/dL or 5.1 to 17.0 mmol/L
- Direct bilirubin (conjugated bilirubin) = 0.1 to 0.3 mg/dL or 1.0 to 5.1 mmol/L
- Indirect bilirubin (unconjugated bilirubin) = (total bilirubin minus direct bilirubin level) = 0.2 to 0.7 mg/dL or 3.4 to 11.9 mmol/L
- Total bilirubin in
- Umbilical cord blood = less than 2 mg/ dl.
- 0 to 1 days = less than 6 mg/ dl
- 0 to 2 days = less than 8 mg/ dl
- 3 to 5 days = less than 12 mg/dl
- after 5 days = less than .2 to 1.0 mg/ dl
- Urine is negative for bilirubin.
- For conversion to SI unit multiply by 17.1 and report as µmol/L (mmol/L)
Another source Total bilirubin level
|0 to 1 day
||1.4 to 8.7
|1 to 2 days
||3.4 to 11.5
|3 to 5 days
||1.5 to 12.0
|5 days to 60 years
||0.3 to 1.2
|60 to 90 year
||0.2 to 1.1
||0.2 to 0.9
Physiologic jaundice of the newborn:
- This is seen in the newborn where the liver is immature and lacks a sufficient amount of conjugating enzymes. This will lead to an increased amount of unconjugated bilirubin.
- This unconjugated bilirubin can cross the blood-brain barrier and give rise to encephalopathy ( Kernicterus ).
Bilirubin above 15 mg /dl in newborn needs immediate treatment.
- This is treated by exchange blood transfusion or light therapy.
Raised Bilirubin level is seen in:
- Some infections, such as an infected gallbladder, or cholecystitis.
- Some inherited diseases, such as Gilbert’s syndrome. Although jaundice may occur in some people with Gilbert’s syndrome, the condition is not harmful.
- Diseases that cause liver damage, such as hepatitis, cirrhosis, or mononucleosis.
- Diseases that cause blockage of the bile ducts, such as gallstones or cancer of the pancreas.
- Rapid destruction of red blood cells in the blood, such as from sickle cell disease or an allergic reaction to blood received during a transfusion (called a transfusion reaction).
- Medicines that may increase bilirubin levels. This includes many antibiotics, some types of birth control pills, indomethacin (Indocin), phenytoin (Dilantin), diazepam (Valium), and flurazepam (Dalmane).
Decreased Bilirubin level is seen in:
- Medicines that may decrease bilirubin levels. This includes vitamin C (ascorbic acid), phenobarbital, and theophylline.
Bilirubin levels that may require treatment in a full-term, healthy baby:
- 24 hours or younger infant need treatment when bilirubin level is More than 10 mg/dL or more than 170 mmol/L.
- 25 to 48 hours infant need treatment when bilirubin is more than 15 mg/dL or more than 255 mmol/L.
- 49 to 72 hours infant needs treatment when bilirubin is more than 18 mg/dL or more than 305 mmol/L
- Older than 72 hours of infant needs treatment when the bilirubin level is more than 20 mg/dL or more than 340 mmol/L
Causes of direct hyperbilirubinemia:
- When more than 50% is direct bilirubin.
- Gallbladder tumors.
- Inflammatory scarring or obstruction of extrahepatic ducts.
- Can be resolved by the surgery.
- Dubin-Johnson syndrome.
- Rotor syndrome.
- Drugs may cause cholestasis.
Causes of Indirect hyperbilirubinemia:
- When less than 15 to 20 % is direct bilirubin.
- Increased RBC hemolysis ( Erythroblastosis fetalis).
- Sickle cell anemia.
- Crigler-Najjar syndrome.
- Gilbert syndrome.
- Congenital enzyme deficiency.
- Transfusion reactions.
- There is no role of surgery.
Types of jaundice may be of following types.
- Pre-hepatic jaundice. The etiology is before the liver like increased hemolysis of RBC.
- Hepatic jaundice. Now the causes are in the liver like hepatitis.
- Post-hepatic jaundice. Where the cause is after the liver like gallstone, cancers and these are the obstructive type of jaundice.
Table showing the Different type of Jaundice and their causes
|Type of Jaundice
||Heme is converted to unconjugated bilirubin
Right heart failure and Cirrhosis
|There is a defect in the delivery of unconjugated bilirubin to liver
Hypothyroidism and Crigler-Najjar syndrome
|There is a defect in the conjugation of bilirubin in the hepatocytes
Drugs like Rifampicin and Gilbert syndrome
|There is a defect in the uptake of unconjugated bilirubin into hepatocytes
Mechanical obstruction by tumors, stones or strictures, and primary biliary cirrhosis
|There is a defect in the flow of conjugated bilirubin through canaliculi and bile ducts. Called cholestatic jaundice.
Drugs like estrogen and cyclosporine
There is a defect in the transmembrane secretion of conjugated bilirubin into the canaliculus. This is also called hepatocellular jaundice
Possible References Used
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