Pathology Handbook

Conjugated bilirubin


Direct-acting bilirubin

Clinical Indications

Bilirubin itself is not water soluble so before excretion, bilirubin in conjugated with glucuronic acid to render it soluble.  Under normal circumstances very little of this conjugated bilirubin reaches the circulation, but conjugated bilirubin is found in serum (and urine) in biliary obstruction.

Request Form 

Request on ICE


On request.  If a patient is found to have a raised total bilirubin and all other liver function tests are normal, the laboratory will automatically reflex a conjugated bilirubin to help in identifying patients with Gilbert's syndrome

Specific Criteria

Test will only be done if the total bilirubin is elevated

Patient Preparation


Turnaround Time

Same day


Serum in yellow top (SST) tube


1 mL


Vacutainer gold top


Bilirubin is photolabile, so samples should be transported to the laboratory as soon as possible after collection

Causes for Rejection

Unlabelled or inadequately labelled sample
Not meeting specific criteria for analysis. 

Reference Range

<6 µmol/L