Specimen requirement

Plasma

Fluid

Adult patient:

 Heparin gel tube

Minimum blood volume: 5 mL

Plain bottle

Minimum volume: 10 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)

Yes

Precaution

Method

Spectrophotometry

Reference interval

(Source: from local population study in 2008)

Neonate:

Term and near term newborns (95th percentile):

24 Hr < 137 µmol/L

48 Hr < 222 µmol/L

84 Hr < 290 µmol/L

Levels > 95th percentile are generally considered to require close supervision, possible further evaluation and sometimes intervention.

Source of reference:

Modified from manufacturer's reagent insert.

Clinical indication

Investigation and monitoring of hepatobiliary disease and haemolysis

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’.

Cyanokit (Hydroxocobalamin) may cause falsely low results. Interference of cyanokit on bilirubin might occur when the testing of bilirubin is done immediately after cyanokit treatment.

Measurement of uncertainty

See table.

Frequency of measurement

Daily