Blood draw
Bilirubin (Indirect/Unconjugated)
Unconjugated bilirubin; hemolysis or liver.
€ 23,00
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Liver and pancreas · Blood
Bilirubin indirect (unconjugated)
Calculated as total minus direct bilirubin; raised in the harmless Gilbert's syndrome or with increased breakdown of blood cells.
At a glance
- Measured in blood
- In 1 test panel
- No special preparation
Explanation
Bilirubin indirect (unconjugated): what is measured?
Unconjugated or indirect bilirubin is not measured separately but calculated: total bilirubin minus conjugated (direct) bilirubin. It is the bilirubin released during the breakdown of red blood cells that the liver has not yet processed. In the blood, this part is bound to albumin. The value rises if more red blood cells are broken down than normal, or if the liver takes up and processes bilirubin more slowly, as in Gilbert's syndrome.
What can it detect?
- Gilbert's syndrome: a harmless inherited trait in which the liver processes bilirubin more slowly
- Increased breakdown of red blood cells (hemolysis)
- Breakdown of blood after a large bruise
Result
What does the result mean?
Bilirubin indirect (unconjugated) too high
A slightly raised unconjugated bilirubin in someone without symptoms, with otherwise normal liver values and a normal blood count, usually fits Gilbert's syndrome (Gilbert's disease). This is a harmless inherited trait: the liver processes bilirubin more slowly, and the value rises with too little food or drink, lack of sleep, stress, an infection or heavy exercise. The whites of the eyes can then temporarily turn slightly yellow; no treatment is needed and it is no threat to health. With increased breakdown of red blood cells (hemolysis) and after a large bruise, it is also mainly the unconjugated part that rises; hemolysis often goes with anemia, tiredness and shortness of breath. Rarely: a severe inherited disorder in the processing of bilirubin (Crigler-Najjar syndrome).
Bilirubin indirect (unconjugated) too low
A low unconjugated bilirubin has no significance. Because it is a calculated value, the outcome can come out very low or zero due to small measurement differences when total bilirubin is low; that is not an abnormality.
After an abnormal result
If only the unconjugated part is raised and the other liver values and blood count are normal, this fits Gilbert's syndrome and usually no further testing is needed; sometimes the GP repeats the measurement after a few weeks. With anemia or other signs of increased breakdown of blood cells, additional blood tests follow, including LDH and reticulocytes, and if needed referral to an internist (specialist in internal medicine).
Reliability
How reliable is the test?
Unconjugated bilirubin is calculated from total and direct bilirubin and adds no new measurement; measurement errors in both values carry over into the calculation. The calculation does show which part of the bilirubin is raised, and that helps in interpreting a raised total bilirubin. If only the unconjugated part is raised and the liver values and blood count are normal, Gilbert's syndrome is by far the most likely explanation. To rule out increased breakdown of red blood cells, the blood count is needed, usually together with LDH and reticulocytes.
What can affect the result?
- Too little food or drink, a strict diet, lack of sleep, stress, an infection and heavy exercise raise the value temporarily, especially in people with Gilbert's syndrome.
- Hemolysis in the tube (with a difficult blood draw or finger prick) and exposure of the sample to light disturb the measurement of total and direct bilirubin, and therefore also the calculation.
- Some medicines, including certain HIV inhibitors, raise unconjugated bilirubin without any liver damage.
- Measurement methods differ between laboratories; at low values the calculation is imprecise.
Who it is for
Who is the test useful for?
Useful for
Useful for interpreting a slightly raised total bilirubin, for example when Gilbert's syndrome is suspected after earlier blood tests, or with occasional slightly yellow whites of the eyes without other symptoms. Also useful, together with the blood count, when increased breakdown of red blood cells is suspected. The value is calculated as soon as total and direct bilirubin have been measured; in healthy adults without symptoms it adds little.
How common is it?
According to Erfelijkheid.nl, about 1 in 20 people have Gilbert's syndrome, more often men than women; it is usually discovered between the ages of 15 and 25. This makes it by far the most common cause of a slightly raised unconjugated bilirubin in healthy adults. Increased breakdown of red blood cells is much rarer.
Erfelijkheid.nl (Erfocentrum); NVKC
Drawbacks and risks
- A slightly raised value due to Gilbert's syndrome is often wrongly taken for liver disease and can lead to unnecessary worry.
Get tested
Bilirubin indirect (unconjugated): test panels
Bilirubin indirect (unconjugated) is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.
Evidence
Sources
This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.
More about risks and resultsMore explanations
Other tests: Liver and pancreas
- ALAT
- Albumin
- Albumin/globulin ratio
- Alkaline phosphatase
- Alpha-1 antitrypsin
- Amylase
- ASAT
- Bilirubin direct (conjugated)
- Bilirubin total
- Ceruloplasmin
- Cholinesterase
- Gamma-GT