What is bilirubin?
A red blood cell lasts about four months. Then it is broken down in your spleen, and the haemoglobin released is converted into bilirubin, a yellow substance that does not dissolve in water. Bound to albumin it travels to your liver, which attaches a sugar group so it becomes soluble, and then drains it through the bile into your gut, where it gives your stool its colour. What circulates in your blood is the sum of the part still waiting for the liver and the part already processed. A high bilirubin therefore has three possible places. Too much supply, when red cells are broken down faster than normal; a liver that does not keep up the processing, through an inherited variant or through liver cell damage; or a drainage that is stuck, through gallstones or a narrowing. The other liver values point the way: ALT and AST high is the liver cell, ALP and gamma-GT high is the drainage, and all normal with many reticulocytes is breakdown. Your report shows bilirubin in µmol/L. Normal is about 4 to 20 µmol/L for a man and 3 to 19 µmol/L for a woman from age 19. Above about double that the whites of the eyes turn yellow; well below that a rise is only visible on paper.
Why is bilirubin relevant?
The reason bilirubin is interesting for anyone healthy is that a slight rise is almost always Gilbert's syndrome. About one in twenty people has an inherited variant of the enzyme that makes bilirubin soluble, and it works somewhat more slowly as a result. The value then sits naturally at the high end and peaks with fasting, a night of poor sleep, an infection or hard exertion, sometimes to a slight yellow tint of the whites of the eyes. It is not a disease and it asks for nothing. More than that: people with Gilbert's have in research actually less cardiovascular disease, because bilirubin is an antioxidant. Anyone who knows it never has to be startled by it again. The second reason is that bilirubin is the last liver value to rise. Gamma-GT, ALT and ALP respond to strain; bilirubin only rises once the liver really no longer keeps up the drainage. A high bilirubin beside a high ALT or ALP is therefore a more serious picture than those values alone, and a normal bilirubin with a raised ALT is reassuring. The third reason is the supply. If red cells are broken down too fast, in haemolysis, bilirubin rises together with LDH and the reticulocytes, while the liver values stay normal. In anyone who runs a lot that happens in a small way with every footstrike, and a bilirubin at the high end belongs to that picture.
Bilirubin reference ranges
What counts beside the number:
- ALT and AST: high alongside is the liver cell
- ALP and gamma-GT: high alongside is the bile drainage, especially with dark urine and pale stool
- LDH and reticulocytes: high alongside is breakdown of red cells
- Whether you were fasting, slept badly or were ill, because that lifts the value
- Whether you know you have Gilbert's, or that it runs in the family
- The colour of the whites of your eyes, because above about double the upper limit they turn yellow
The bands above are where the labs overlap; the upper limit differs by a few units per lab. In Gilbert's syndrome, which one in twenty people has, the value sits naturally above the band without anything being wrong, and peaks with fasting and poor sleep. Above about double the upper limit the whites of the eyes turn yellow. Always read bilirubin beside the other liver values.
What Dutch labs actually use
3 – 19µmol/L
Between 0 and 3 and between 19 and 21 it depends on the lab, because each sets its limits on its own method and population. Above 21 every lab calls it abnormal.
every lab calls 3 – 19 µmol/L normal. Between 0 and 3 and between 19 and 21 it depends on the lab.
Every age, per lab
| Laboratory | Group | Reference range |
|---|---|---|
| Unilabs(Saltro, Medlon, SHO, Atalmedial)2026 | 1 month to 115 yrs | 3–20 µmol/L |
| Star-shl2026 | Men 13–18 yrs | 4–29 µmol/L |
| Women 13–18 yrs | 3–22 µmol/L | |
| Men 19+ | 4–24 µmol/L | |
| Women 19+ | 3–19 µmol/L | |
| Certe2026 | Men from 18 yrs | < 24 µmol/L |
| Women from 18 yrs | < 19 µmol/L | |
| Clinical Diagnostics2026 | Infant from 3 wks | < 25 µmol/L |
| Adult | < 21 µmol/L |
Each band as the lab publishes it, retrieved in 2026, unless marked otherwise.
Bilirubin high or low: what it means
A high bilirubin means too much supply, a liver that does not keep up or a drainage that is stuck. Usually it is the first and rarely the last: Gilbert's syndrome, fasting or a night of poor sleep, liver strain from alcohol, medicines or a virus, bile congestion, and rarely an accelerated breakdown of red blood cells. The other values point the way. Only bilirubin slightly raised, everything else normal: Gilbert's or fasting, and a repeat after normal eating and sleeping lets it fall. Bilirubin high with high ALT and AST: the liver cell. Bilirubin high with high ALP and gamma-GT, and dark urine and pale stool: the drainage, and then time counts. Bilirubin high with high LDH and many reticulocytes: breakdown. A low bilirubin means nothing; it is not a deficiency and nothing belongs with it. What you do about it: with Gilbert's nothing, except remembering it, so that at a next result you know what it is. With a rise after fasting or poor sleep you have blood drawn again after a normal week. With liver strain, alcohol and medicines are the first questions. With a bile picture an ultrasound of the bile ducts belongs, and with jaundice with dark urine that belongs at short notice. Bilirubin belongs beside ALT, AST, gamma-GT and ALP, and with a rise without a liver picture beside LDH and the reticulocytes. Do not fast longer than an ordinary night, because fasting lifts the value.
What lowers it
Not a finding; little bilirubin is little breakdown or a brisk liver.
| Cause | How often |
|---|---|
| Naturally lowAnyone who breaks down few red cells and has a liver that processes briskly sits low in the band, and that means nothing | Often |
What raises it
Too much supply, a liver that does not keep up, or a drainage that is stuck.
| Cause | How often |
|---|---|
| Gilbert's syndromeAn inherited variant of the enzyme that makes bilirubin soluble, in one in twenty people; the value sits naturally at the high end and does no harm | Often |
| Fasting or a night of poor sleepFasting, little sleep, an infection and hard exertion lift bilirubin temporarily, especially in anyone with Gilbert's; a repeat after a normal week lets it fall | Often |
| Liver strainAlcohol, medicines or a virus damaging the liver cells; ALT and AST then sit high too, and bilirubin is the last to rise | Sometimes |
| Blocked bile flowGallstones, a narrowing or inflammation of the bile ducts; ALP and gamma-GT rise with it, the urine turns dark and the stool pale | Sometimes |
| Accelerated breakdown of red blood cellsIn haemolysis bilirubin rises together with LDH and the reticulocytes while the liver values stay normal; in runners that happens in a small way | Rare |
How does a bilirubin blood test work?
- Referral
- Not needed. Bilirubin is in every liver panel you can have measured yourself.
- Fasting
- An ordinary night is fine, but not longer, because prolonged fasting lifts bilirubin, especially in anyone with Gilbert's.
- When
- After a normal week with enough sleep and without an infection, if you want to know your usual value.
- The draw
- One tube of blood from a vein in your arm, protected from light, because bilirubin breaks down in daylight. The other liver values come from the same draw.
- Repeating
- With a slight rise without a liver picture after a normal week, to confirm Gilbert's or fasting; with a bile picture together with an ultrasound of the bile ducts.
- Which test
- Bilirubin is in the comprehensive test (€229) and in .
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What is bilirubin?
The yellow breakdown product of old red blood cells. Your spleen breaks down worn cells every day, the haemoglobin from them becomes bilirubin, your liver makes it soluble and drains it through the bile into the gut, where it colours your stool. If it builds up, it colours your skin and the whites of your eyes yellow. This test measures the total: the part still waiting for the liver plus the part already processed.
What is a normal bilirubin level?
About 4 to 20 µmol/L for a man and 3 to 19 µmol/L for a woman from age 19, where the labs overlap. In Gilbert's syndrome the value sits naturally higher without anything being wrong. More important than the band is the company of the other liver values, and whether you were fasting or slept badly.
What does a high bilirubin mean?
Too much supply, a liver that does not keep up the processing, or a bile drainage that is stuck. Only bilirubin slightly raised with otherwise normal liver values is almost always Gilbert's syndrome or a day of fasting, and that does no harm. High with a high ALT is the liver cell; high with a high ALP and gamma-GT, dark urine and pale stool is the bile drainage; high with a high LDH and many reticulocytes is breakdown of red cells.
What is Gilbert's syndrome?
An inherited variant of the enzyme that makes bilirubin soluble, in about one in twenty people. The liver processes somewhat more slowly as a result, and the value sits naturally at the high end and peaks with fasting, poor sleep, an infection or hard exertion, sometimes with a slight yellow tint of the whites of the eyes. It is not a disease, asks for nothing and in research even goes together with less cardiovascular disease, because bilirubin is an antioxidant. Anyone who knows it never has to be startled by it again.
When does jaundice arise?
When bilirubin goes above about double the upper limit, first the whites of the eyes turn yellow and then the skin. In Gilbert's that happens slightly and temporarily, with fasting or illness. With a bile drainage that is stuck or a liver that no longer keeps up, dark urine and pale stool come with it, often with itching and pain in the upper right, and then time counts.
Can a low bilirubin do harm?
No. A low bilirubin means little breakdown of red cells or a liver that processes briskly, and nothing belongs with it. The test exists to find a rise.
Why does bilirubin rise with fasting and poor sleep?
Because with little food the liver puts less energy into making bilirubin soluble, and because poor sleep, an infection and hard exertion do the same. In anyone with Gilbert's that effect is strongest. So have blood drawn after an ordinary night and a normal week, and not after a long fast, if you want to know your own value.
Do I need to fast for a bilirubin test?
An ordinary night is fine, longer is not, because fasting lifts the value. The tube is protected from light, because bilirubin breaks down in daylight. The other liver values come from the same draw, and without those bilirubin cannot be read.
Which tests include bilirubin?
Bilirubin is in the Liver function test (€59, also as an add-on for €15), in the comprehensive test (€229) and in .
Related biomarkers
Sources
- 1.Unilabs, test catalogue (Dutch): total bilirubin. 2026. bepalingenklapper.nl
- 2.Star-shl, test catalogue (Dutch): total bilirubin. 2026. star-shl.nl
- 3.Certe, test catalogue (Dutch): total bilirubin. 2026. bepalingenwijzer.certe.nl
- 4.Clinical Diagnostics, lab guide (Dutch): total bilirubin. 2026. clinicaldiagnostics.nl
- 5.LESA Laboratory diagnostics (Dutch primary-care laboratory agreement). 2026. richtlijnen.nhg.org
Educational information only, not medical advice. Consult a healthcare professional for clinical decisions.
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