Adult patient:
Heparin gel tube
Minimum blood volume: 5 mL
Paediatric patient:
Paediatric heparin tube
Number of vials: 1
Minimum blood volume: 1.3 mL
Authorisation code required
No
24 Hr available service
Yes
(Call extension: 3353 for express result)
Method
Spectrophotometry
Reference interval
< 5 µmol/L
(Source: from local population study in 2008)
Clinical indication
Investigation and monitoring of hepatobiliary disease and haemolysis
In most circumstances total bilirubin is sufficient.
Result interpretation
Total bilirubin comprises unconjugated, conjugated and delta bilirubin, whereas direct bilirubin comprises conjugated and delta bilirubin.
High levels of total and direct bilirubin are seen with hepatocellular disease or biliary disease (intra- or extra-hepatic).
Delta bilirubin, which is covalently bound to albumin, has a longer half-life in the circulation than the other bilirubins and may cause bilirubin elevation for some time after the others have returned to normal.
Isolated elevation of unconjugated bilirubin (that is elevated total bilirubin with normal direct bilirubin) occurs when the rate of production exceeds the rate of conjugation. It is seen in haemolysis and in megaloblastic anaemia, but the commonest cause is the Gilbert syndrome, in which there is a non-pathogenic impairment of bilirubin conjugation. Physiological jaundice in neonates is due to elevated unconjugated bilirubin.
Normal levels of bilirubin may be present in uncomplicated cirrhosis, early in the course of fulminant liver failure, or with hepatic metastases until the disease is advanced.
Indocyanine Green (ICG), also known as 'IC-Green', is a medically used contrast medium leading to a contrast enhancement of tissue or fluids for diagnostic purposes in the human body. The present of ICG in patient samples will lead to implausible high bilirubin results. ‘Samples containing indocyanine green must not be measured’.
Measurement of uncertainty
Frequency of measurement
Daily