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Bilirubin, Direct

Test ID: A937

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Bilirubin is a degradation product formed during the normal and abnormal destruction of red blood cells. Total bilirubin consists of conjugated and unconjugated bilirubin. Direct bilirubin provides an estimate of how much conjugated bilirubin is present. A total bilirubin test is usually conducted first and a direct bilirubin test is only required to further evaluate individuals with elevated total bilirubin.

Elevated direct bilirubin can occur when there is impaired removal of bilirubin from the body, which can be caused by blockages in the bile ducts of the liver and gallbladder, or other liver diseases (e.g. hepatitis, cirrhosis, or liver cancer).



How to order a test

What is Included?

Measurement of direct bilirubin levels in a blood sample by the diazo reaction methodology.

Turnaround Time

1 – 3 business days
The turnaround time is not guaranteed. The average turnaround time is 1 – 3 business days from the date that the sample arrives at the laboratory. Shipping time for the sample is not included. Additional time is required if the case requires confirmatory or reflex testing, or if the sample is insufficient, or if a recollection is required.

Related Documents

Additional Information and Resources


Preparation Before Specimen Collection


Specimen Type



50 μL in a microtainer


Microtainer (regular blood tube)

Collection Method

This test requires a blood sample from a finger prick. All supplies for sample collection are provided in the kit.

  1. First wash and dry hands. Warm hands aid in blood collection.
  2. Clean the finger prick site with the alcohol swab and allow to air dry.
  3. Use the provided lancet to puncture the skin in one quick, continuous and deliberate stroke.
  4. Wipe away the first drop of blood.
  5. Massage hand and finger to increase blood flow to the puncture site. Angle arm and hand downwards to facilitate blood collection on the fingertip.
  6. Drip blood into the microtainer tube.
  7. Dispose of all sharps safely and return sample to the laboratory in the provided prepaid return shipping envelope.

NOTES: Avoid squeezing or ‘milking’ the finger excessively. If more blood is required and blood flow stops, perform a second skin puncture on another finger. Do not touch the fingertip.

Specimen Storage

Maintain specimen at temperatures between 2°C and 30°C during storage and transport.

Ensure that the blood sample is not exposed to bright light.

Specimen Stability

Blood samples can be refrigerated or kept at room temperature for up to 7 days.

Causes for Rejection

  • Incorrect or incomplete patient identification
  • Incorrect specimen collection
  • Inappropriate storage and transport conditions
  • Incorrect specimen volume



To measure direct bilirubin levels in a blood sample predominantly for the detection of liver disease.

Bilirubin is a normal degradation product from the destruction of aged or abnormal red blood cells. However, elevated levels can occur when there is increased breakdown of red blood cells or impaired removal of bilirubin from the body. Elevated direct bilirubin is usually associated with decreased elimination of bilirubin by the liver cells, or blockage of the bile ducts. Decreased elimination may be caused by viral hepatitis, drug reactions, or alcoholic liver disease, while blockages can occur due tov gallstones, tumors, or scarring of the bile ducts


  • This report is not intended for use in medico-legal applications.
  • These results should be interpreted in conjunction with other laboratory and clinical information.
  • Correct specimen collection and handling is required for optimal assay performance.
  • Indocyanine green (ICG) may interfere with this assay. Specimens from individuals undergoing evaluations using ICG must be collected after ICG has been eliminated.
  • Fasting, caffeine, and certain medications and supplements, including some birth control pills, some antibiotics, Valium, and vitamin C can affect bilirubin levels.


Diazo reaction methodology (Alinity c Direct Bilirubin assay)

Reference Intervals

Normal direct bilirubin levels in serum or plasma are less than 0.3 mg/dL.

This reference range was obtained from Reed R. (2020). Clinical Chemistry Learning Guide Series. Editors Armbruster D & Cooper K. Abbott. .