Bilirubin is formed by the breakdown of haemoglobin (unconjugated/indirect bilirubin) and converted to water-soluble form by hepatocytes, (conjugated or direct bilirubin.) It is then secreted into bile and passed into the gut. Most are reabsorbed by the liver, whilst the remainder is converted to urobilinogen, and either reabsorbed by the kidneys or excreted by the faeces after conversion to stercobilin. Jaundice is yellow discolouration to the skin or sclera due to hyperbilirubinaemia. Elevated levels of bilirubin may indicate an obstruction of bile flow or a problem in the processing of bile by the liver.
Bilirubin is produced as a by-product of haemoglobin metabolism and testing for Bilirubin is usually one of a group of tests used to investigate the health of the liver.
There are 3 main causes of jaundice : pre-hepatic (raised indirect unconjugated bilirubin), inter-hepatic (mixed picture of raised direct and indirect bilirubin) and post-hepatic (raised conjugated hyperbilirubinaemia).
The most common cause of an isolated high bilirubin level is Gilberts syndrome and haemolysis.
Pre-hepatic raised unconjugated/indirect bilirubin
- Haemolysis – check FBC also
- Gilbert’s syndrome
- Haematoma reabsorption
- Post viral hepatitis
- Mild chronic hepatitis
- Crigler-Najjar syndrome
Interhepatic causes of conjugated/direct hyperbilirubinaemia
- Hepatocellular disease
- Viral infections (hepatitis ABC, EBV, CMV)
- Chronic alcohol use
- Autoimmune disorders
- Drug toxicity
- Parental nutrition
- Inherited defects of excretion
- Dublin Johnson Syndrome
- Rotors Syndrome
- Primary biliary cirrhosis
- Primary sclerosing cholangitis
- Hepatocellular carcinoma
Post-hepatic causes of conjugated direct hyperbilirubinaemia
- Intra-luminal causes : gallstones, cholestasis from blocked common bile duct, Infection
- Mural causes : intrahepatic malignancy, cholangiocarcinoma, surgical strictures or drug-induced cholestasis
- Extra-mural causes: pancreatic cancer, lymphomas, pancreatitis
5mL venous serum or plasma
In addition to the packaging of samples, the transport/delivery of clinical samples to the laboratory is required to be in adherence to all national regulations for the safe transport of biological materials. Enfer Medical provides a fully compliant logistics service, aligned with clients’ testing requirements.
Prompt transport of specimens:
To ensure prompt testing of samples and release of results within the published test turnaround times, samples should arrive to the laboratory by 18:00. Test turnaround time is measured from receipt of the sample at the laboratory until the time the authorised results are reported to users.
In rare cases specimens may not be suitable for testing on arrival to the laboratory. In that case the sample will be rejected at the receipt stage and the service user will be notified immediately and an explanation as to why the sample could not be processed will be provided. Reasons why samples cannot be processed include but are not limited to:
- Samples received beyond the stability limits and/or not at the correct temperature indicated for each test.
- Incorrect sample type received.
- Leaking samples, sample not received or sample insufficient for analysis as stated below within sample requirements.
- Non-compliant samples or request forms i.e. those missing sample date information, missing sample test request and/or missing sample site/type information.
- Samples received without the necessary patient identifiers.
Quantitative results for Bilirubin Total are reported in numeric value in µmol/L. Please contact us for more information on the reference ranges used at Enfer Medical.