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Liver

Direct bilirubin: what conjugated bilirubin says about the liver and bile ducts

According to the Cleveland Clinic, bilirubin is a waste product left when old red blood cells are broken down; the liver sorts this yellow substance into bile, and bile leaves the body through the intestines. In the liver, bilirubin is bound to a sugar molecule, which makes it dissolve in water so it can mix with bile. That processed form is called conjugated or direct bilirubin.

According to the Cleveland Clinic, a raised direct bilirubin can mean that the body is having trouble clearing the processed bilirubin, and that might indicate a biliary disease or gallstones. Too much bilirubin can cause jaundice, yellow skin and yellow eyes, but according to the Cleveland Clinic high bilirubin is also possible without visible signs, so only a blood test shows the level.

Star-SHL uses 0 to 5 µmol/l for direct bilirubin and Unilabs 0 to 4 µmol/l. Certe uses less than 5 µmol/l above the age of 14 days, and Diagnostiek voor U less than 3.4 µmol/l.

Doctor's Assessment Included

Direct bilirubin is the bilirubin the liver has already processed and readied for the bile. According to the Cleveland Clinic, a rise might indicate gallstones or a biliary disease.

  • For direct bilirubin, Star-SHL uses 0 to 5 µmol/l, Unilabs 0 to 4 µmol/l, Certe less than 5 µmol/l above the age of 14 days and Diagnostiek voor U less than 3.4 µmol/l.
  • According to the Cleveland Clinic, conditions that affect processing in the liver raise both direct and indirect bilirubin.
  • According to the Cleveland Clinic, high bilirubin can exist without visible jaundice.

Reference Ranges

See the value that applies to you:

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

Male Your group
umol/l
Normal < 5 High
Female Your group
umol/l
Normal < 5 High

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

Bilirubin (Direct): what Dutch laboratories use

The upper limit runs from 3.4 umol/l at Diagnostiek voor U to 5 umol/l at Star-shl.

Reference ranges by group, in umol/l
Star-shl · Everyone 0–5 umol/l
0 5
Unilabs · Everyone 0–4 µmol/l
0 4
Certe · Everyone · 0 years and older · a limit, not a range < 5 umol/L
5
Diagnostiek voor U · Everyone · a limit, not a range < 3.4 µmol/L
3.4
0 5.5 umol/l

Source: Star-shl

Source: Unilabs

Source: Certe

Source: Diagnostiek voor U

Each value as the laboratory itself publishes it, retrieved in 2026.

Bilirubin (Direct): what this test measures

The direct bilirubin test measures the amount of conjugated bilirubin in the blood, in micromoles per litre (µmol/l). According to the Cleveland Clinic, this form is called direct because it can be measured directly; the indirect, not yet processed bilirubin is calculated by subtracting the direct from the total bilirubin. Unilabs determines the value with a diazo reaction and asks for the blood to be kept in the dark as much as possible.

Bilirubin (Direct): why this value matters

Direct bilirubin matters because the Cleveland Clinic links a rise in this form to trouble clearing bilirubin, which might indicate a biliary disease or gallstones. According to the Cleveland Clinic, conditions that affect the liver's ability to process bilirubin make both forms rise, the direct and the indirect. According to the Cleveland Clinic, the bilirubin test is part of a panel of liver function tests that measure different liver products in the blood.

Bilirubin (Direct): how the blood test works

Referral
No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw
A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Which test
Liver checkup · €89,-
Where
650+ draw sites run by independent laboratories across the Netherlands. Draw sites

Bilirubin (Direct): when is testing worthwhile?

According to MedlinePlus, a bilirubin test may be ordered for symptoms such as jaundice, dark urine, clay-coloured stool or stomach pain, to find a blockage in the bile ducts, or to monitor an existing liver disease. According to the Cleveland Clinic, visible jaundice, yellowing of the skin and eyes, is a sure sign to see a provider for a bilirubin test. According to the Cleveland Clinic, the provider might ask you not to eat or drink for a few hours before the blood draw.

Bilirubin (Direct): symptoms of a high or low value

Low Levels

A direct bilirubin that is too low does not appear in the sources read. For bilirubin in general, the Cleveland Clinic and MedlinePlus call low levels usually not a cause for concern, and according to both, medicines can lower bilirubin; the Cleveland Clinic names antibiotics and birth control pills, among others.

High Levels

According to the Cleveland Clinic, a high direct bilirubin might indicate gallstones, an inflammation of the gallbladder (cholecystitis) or an inflammation of the bile ducts (cholangitis). High bilirubin can cause jaundice, a yellow cast to the skin and the whites of the eyes, and can make the urine darker; if bilirubin does not come out in the stool as it should, the stool might be lighter or clay-coloured, and very high bilirubin can cause itching. According to the Cleveland Clinic, jaundice becomes visible when bilirubin is two to three times the normal range.

Bilirubin (Direct): causes of a low or high value

What raises the value

  • Gallstones

    Higher direct bilirubin can mean the body is having trouble clearing it, which might indicate gallstones.

  • Inflammation of the gallbladder (cholecystitis)

    Higher direct bilirubin might indicate a biliary disease, such as an inflamed gallbladder.

  • Inflammation of the bile ducts (cholangitis)

    Higher direct bilirubin might indicate a biliary disease, such as inflamed bile ducts.

  • Liver conditions that affect the processing of bilirubin

    Conditions that affect the liver's ability to process bilirubin cause high levels of both types, the direct one included.

Bilirubin (Direct): lifestyle and this value

According to the Cleveland Clinic, a raised direct bilirubin goes down when the condition that makes it rise is treated effectively, so the cause decides what needs to happen. According to the Cleveland Clinic, you can in general reduce stress on the liver by avoiding alcohol and drugs, including over-the-counter medicines where possible, and by eating a healthy diet. Discuss a raised value with your GP.

Bilirubin (Direct): frequently asked questions

What is the difference between direct and indirect bilirubin?

Direct bilirubin is the bilirubin the liver has already processed and bound to a sugar molecule, indirect bilirubin is the form still on its way to the liver. According to the Cleveland Clinic, only the direct form can be measured directly, and the indirect is calculated as total minus direct bilirubin.

Can bilirubin end up in the urine?

According to the Cleveland Clinic, bilirubin in urine is not normal, but it might happen when the conjugated, direct bilirubin is very high.

Bilirubin (Direct): sources

  1. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  2. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  3. Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
  4. Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
  5. Cleveland Clinic Health Library, Bilirubin Test, my.clevelandclinic.org, geraadpleegd 2026-10-18 (retrieved 2026) my.clevelandclinic.org

Test Products

This marker is included in the following test panels.

Medical reviewer

Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
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Bilirubin (Direct)

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