Bilirubin, Indirect (Unconjugated)
Indirect bilirubin is the unconjugated form that has not yet been processed by the liver. Elevated levels often indicate excessive red blood cell breakdown or conditions like Gilbert's syndrome.
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What the Bilirubin, Indirect (Unconjugated) test tells you
Red blood cells live for a few months, and when they are retired the haemoglobin inside them is broken down into a yellow-orange pigment called bilirubin. At this stage the pigment does not dissolve in water, so it travels through the bloodstream attached to albumin. This circulating, not-yet-processed form is what the indirect or unconjugated bilirubin measurement captures. Laboratories usually derive it by subtracting the direct fraction from the total.
The liver's job is to collect this pigment, attach a sugar to it and send it out in bile. Anything that overwhelms that production line pushes the unconjugated fraction up, and the two broad mechanisms are supply and processing: red cells being destroyed faster than usual, or liver cells taking up and conjugating bilirubin more slowly than usual. Gilbert's syndrome, a common and harmless inherited variation in the conjugating enzyme, belongs to the second group and is one of the most frequent reasons a healthy person is found to have a mildly raised unconjugated bilirubin, often noticed after fasting, illness or a poor night's sleep.
Because the unconjugated form is bound to albumin, it does not pass into urine: urine keeps its usual colour even when the skin looks yellow, and that observation is itself a clue. Interpretation leans on the surrounding tests: a full blood count and reticulocytes if red cell breakdown is suspected, liver enzymes and the direct fraction if the liver is. In newborns the same pigment is watched far more closely, because the unconjugated form can cross into the developing brain.
Ordered to evaluate unexplained anaemia, suspected haemolysis, or to confirm benign conditions like Gilbert's syndrome.
- Separating jaundice causes
Splitting total bilirubin into fractions shows whether yellowing comes from red-cell breakdown or from the liver's processing step. That distinction changes what is investigated next.
- Investigating anaemia
When anaemia is suspected of being caused by red cells breaking apart, the unconjugated fraction usually rises. It is checked alongside the blood count and reticulocytes.
- Confirming Gilbert's syndrome
A mild isolated rise with otherwise normal liver tests is the classic picture of this harmless inherited variation. Recognising it prevents unnecessary further testing.
- Explaining transfusion effects
After a transfusion or a large internal bruise, extra red-cell pigment is released and processed. Measuring this fraction helps confirm what is happening.
Reasons your doctor may request the Bilirubin, Indirect (Unconjugated) test
Your doctor may order this test for any of the reasons below. Some are routine checks, others follow specific symptoms or an earlier result.
Jaundice with normal urine
- Yellowing of the skin or eyes while urine remains normal in colour.
Anaemia & red-cell breakdown
- Anaemia that is unexplained, or blood-count results suggesting red cells are being destroyed.
- Follow-up after a blood transfusion or a large bruise, or in known sickle cell or thalassaemia conditions.
Inherited causes
- A mildly raised total bilirubin found incidentally with otherwise normal liver tests.
- A family history of Gilbert's syndrome or of an inherited red-cell disorder.
A result in the Normal band, up to 1 mg/dL, is the usual finding. Indirect (unconjugated) bilirubin is the form made when old red cells are broken down, before the liver processes it, and it is usually calculated as total minus direct bilirubin. A result in the Mildly raised band, 1.1 to 3 mg/dL, with otherwise normal liver tests is most often Gilbert's syndrome, a common harmless trait that makes levels climb during fasting, illness or stress. A result in the High band, above 3 mg/dL, suggests red cells are being broken down faster than normal, as in some inherited red cell conditions, G6PD deficiency after a trigger or a reaction to medicines, and should be discussed with your doctor. A full blood count, reticulocyte count and LDH help separate red cell breakdown from Gilbert's syndrome. Newborn babies have their own limits.
Medically reviewed by Dr Nirupama Sabhapathy
Ranges are a guide: your physician interprets your result alongside your symptoms and history.
What a higher result can point to
- Haemolysis: red blood cells breaking down faster than the body replaces them.
- Gilbert's syndrome, a common inherited reduction in the liver's conjugating enzyme activity.
- Ineffective production of red cells in the bone marrow, as in some thalassaemias and vitamin deficiencies.
- Reabsorption of blood from a large bruise, an internal bleed or a recent transfusion.
- Rarer inherited enzyme deficiencies such as Crigler-Najjar syndrome.
- Prolonged fasting or an acute illness, which can temporarily lift the unconjugated fraction.
These are possibilities, not diagnoses. A single value outside the reference range is interpreted alongside your symptoms, history and other tests: your doctor decides what it means for you.
What this test cannot tell you
- A low result is not clinically meaningful; this measurement is interpreted only when the value is raised.
- The figure is usually calculated rather than measured directly, so it inherits any inaccuracy in the total and direct results.
- It identifies the pattern but not the cause; a blood count, reticulocyte count or liver imaging is generally needed to go further.
Risks of the blood draw
- Mild bruising or brief soreness where the needle went in.
- Occasional lightheadedness, which settles after a few minutes of rest.
- Bleeding or infection at the site, which is rare with sterile single-use equipment.
- 1Unconjugated bilirubin is the pigment released from old red blood cells before the liver has processed it.
- 2A rise means either more pigment is being made or the liver is conjugating it more slowly.
- 3Because it is carried on albumin it does not enter urine, so urine colour stays normal.
- 4Gilbert's syndrome is a common, benign explanation for a mild isolated elevation.
- 5The result is read together with the full blood count and the rest of the liver panel.
Bilirubin, Indirect (Unconjugated) is also part of these health checkups, which add a wider screen in the same appointment.
Bilirubin, Indirect (Unconjugated) also comes in these focused packages, which pair it with the tests usually read alongside it.
- BiochemistryBilirubin, Total
Total bilirubin combines direct and indirect bilirubin levels. It is a standard part of liver function panels and helps assess liver health, bile…
15View - BiochemistryBilirubin, Direct
Direct (conjugated) bilirubin is the water-soluble form processed by the liver. Elevated levels suggest liver disease or bile duct blockage and are a…
15View - HaematologyComplete Blood Count (CBC)
The CBC is the most commonly ordered blood test. It measures red blood cells, white blood cells, haemoglobin, haematocrit, and platelets to assess…
35View - HaematologyReticulocyte Count
Reticulocytes are immature red blood cells freshly released from bone marrow. This count reflects how actively your bone marrow is producing red…
25View
Frequently Asked Questions
Everything you need to know about the Bilirubin, Indirect (Unconjugated) test. Can't find what you're looking for?
Talk to our team→Our laboratory reports 0.1 to 1 mg/dL as normal. A result of 1.1 to 3 mg/dL is reported as mildly raised and, with otherwise normal liver tests, is most often Gilbert's syndrome. Above 3 mg/dL is reported as high and suggests red cells are being broken down faster than normal. Newborn babies have their own limits.
It means either more pigment is being made from broken-down red cells or the liver is conjugating it more slowly. Common explanations are Gilbert's syndrome, haemolysis, ineffective red cell production as in some thalassaemias, and reabsorption of blood from a large bruise or recent transfusion. The result shows the pattern, not the cause, so further tests usually follow.
Indirect bilirubin is the pigment released from old red cells before the liver has processed it; direct bilirubin is the form after the liver has conjugated it for excretion in bile. A rise in the indirect fraction points towards red cell breakdown or slow conjugation, while a rise in the direct fraction points towards a liver or bile-flow problem.
Yes. In G6PD deficiency, red cells can break down quickly after a trigger such as an infection or certain medicines, sending indirect bilirubin up. Some thalassaemias raise it through ineffective red cell production in the bone marrow. Both are relevant in the Gulf, and a blood count with a reticulocyte count helps your doctor tell them apart from Gilbert's syndrome.
A full blood count, reticulocyte count and LDH help separate red cell breakdown from Gilbert's syndrome, and the rest of the liver panel shows whether the liver itself is involved. If those are normal and the rise is mild, Gilbert's syndrome is the likely explanation; otherwise your doctor may add further blood tests or liver imaging.
It is a lifelong variation in how quickly the liver processes bilirubin, and it does not damage the liver or shorten life. People who have it may notice mild yellowing when they are unwell, fasting or short of sleep, and no treatment is needed.
The unconjugated form travels bound to albumin, and the kidneys cannot filter it. Yellow skin with normal-coloured urine is a recognised pattern that points towards this fraction rather than a bile-flow problem.
Most laboratories measure total and direct bilirubin and derive the indirect fraction from the difference between them. That is why it is always reported alongside the other two.
Yes. A long fast, dehydration and hard physical exertion can all nudge the unconjugated fraction upward for a while, particularly in people with Gilbert's syndrome. Repeating the test in a settled week often resolves the question.
No, and it is better not to. Going many hours without food can itself raise the unconjugated fraction, so eating normally the day before gives a cleaner result, especially when a borderline value is being rechecked. Stay well hydrated and avoid alcohol for a day or two beforehand.
The indirect bilirubin test is AED 15, including a physician-reviewed report, with results usually within 24 hours. Home collection anywhere in Dubai is free when your order reaches AED 300 or includes a package; below that, a AED 100 home collection fee applies (AED 50 for a lab walk-in).