High Bilirubin
Bilirubin is the yellow pigment made when old red blood cells are recycled. The liver processes it and sends it out in bile. A mildly high level with otherwise normal liver tests is very often Gilbert’s syndrome, which is harmless.
Quick answer: Total bilirubin above about 20 µmol/L (1.2 mg/dL) is high. A mild rise that’s mostly unconjugated, with normal liver tests and blood count, is usually Gilbert’s syndrome. Liver disease, blocked bile ducts and red cells breaking down are the other main causes. Yellow skin with dark urine, pale stools, fever or pain needs prompt review.
What the test measures
Bilirubin comes in two forms, and labs can split the total:
- Unconjugated (indirect) bilirubin is made when red cells are broken down, before the liver has processed it. It rises in Gilbert’s syndrome and when red cells break down too fast (haemolysis).
- Conjugated (direct) bilirubin has been processed by the liver. It rises with liver disease and blocked bile ducts.
The split, plus the other liver tests and a full blood count, tells your doctor where to look.
Typical adult ranges
- Total bilirubin: up to about 20 µmol/L (about 1.2 mg/dL in US units).
- Conjugated bilirubin: usually under about 4–7 µmol/L, depending on the lab.
- To convert, multiply mg/dL by 17.1 to get µmol/L.
- Visible jaundice (yellow eyes or skin) usually appears once total bilirubin is above about 50 µmol/L (3 mg/dL).
- This page is about adults. Jaundice in newborns is different and is checked by the baby’s midwife or doctor.
What a high result usually means
Common causes:
- Gilbert’s syndrome: a harmless inherited quirk affecting about 5–8% of people. Bilirubin is mostly unconjugated and rises with fasting, illness, dehydration or stress. See Gilbert’s syndrome.
- Liver inflammation from fatty liver, alcohol or viral hepatitis, usually with a raised ALT. See high ALT.
- Gallstones blocking the bile duct, often with pain under the right ribs. See gallstones.
- Medicines: some antibiotics (such as amoxicillin with clavulanic acid) and other medicines can slow bile flow.
- Red cells breaking down (haemolysis): inherited conditions such as hereditary spherocytosis, G6PD deficiency, sickle cell disease or thalassaemia, or immune causes.
Less common but important:
- Cancer of the pancreas, bile ducts or liver, which can block bile flow. The classic sign is painless jaundice with itch, dark urine, pale stools or weight loss.
- Autoimmune and bile duct diseases: autoimmune hepatitis, primary biliary cholangitis, primary sclerosing cholangitis.
- Acute liver failure, for example after a paracetamol overdose.
- Rare inherited conditions such as Crigler–Najjar, Dubin–Johnson and Rotor syndromes.
Symptoms
- Often none, especially in Gilbert’s syndrome.
- Yellowing of the whites of the eyes, then the skin.
- Dark urine, pale or clay-coloured stools and itch suggest bile isn’t draining.
- Tiredness, tummy pain, fever or weight loss, depending on the cause.
What happens next
- Repeat the liver tests with the bilirubin split into unconjugated and conjugated, and a full blood count.
- Mostly unconjugated, normal blood count and normal other liver tests: almost always Gilbert’s syndrome. No further tests or treatment are usually needed.
- Anaemia as well: tests for haemolysis, such as a reticulocyte count, LDH, haptoglobin and a blood film.
- Unconjugated bilirubin over about 40 µmol/L: guidelines suggest considering rarer inherited causes.
- Mostly conjugated, or other liver tests abnormal: a liver screen (hepatitis, iron, autoimmune tests) and a liver ultrasound to look for a blockage.
Get urgent help (000 in Australia, or your local emergency number) for jaundice with confusion or drowsiness, vomiting blood or black bowel motions, or after taking too much paracetamol. See a doctor the same day for jaundice with fever, shivers or pain under the right ribs: this can be a blocked, infected bile duct (cholangitis). See your GP within a week for new yellowing with dark urine, pale stools, itch or weight loss, especially if you’re 40 or over: NICE advises urgent suspected-cancer referral for jaundice from age 40.
Practise reading results. Play Panelysis, the daily blood-test puzzle: a fictional patient, a real-looking panel, three guesses. More in medical games.
Common questions
Is high bilirubin dangerous?
Usually not when it’s mild and mostly unconjugated with otherwise normal tests, which is typical of Gilbert’s syndrome. It matters more when the conjugated part is high, other liver tests are abnormal, or you have jaundice with dark urine, pale stools, fever or pain.
What bilirubin level is concerning?
Above about 20 µmol/L (1.2 mg/dL) is outside the usual range, and jaundice usually shows above about 50 µmol/L (3 mg/dL). The type of bilirubin, your other liver tests and your symptoms matter more than the exact number.
What’s the difference between direct and indirect bilirubin?
Indirect (unconjugated) bilirubin hasn’t yet been processed by the liver, and rises in Gilbert’s syndrome and when red cells break down. Direct (conjugated) bilirubin has been processed, and rises with liver disease or blocked bile ducts.
Can fasting raise bilirubin?
Yes, in people with Gilbert’s syndrome. Skipping meals, illness, dehydration, hard exercise and stress can all push bilirubin up for a while. It settles once you eat normally and recover.
Is Gilbert’s syndrome serious?
No. It’s a common, harmless inherited condition that doesn’t damage the liver, needs no treatment and doesn’t shorten life. Guidelines advise doctors to reassure people once the diagnosis is clear.
Why are my eyes yellow but I feel fine?
Mild yellowing that comes and goes, especially when you’re unwell or haven’t eaten, is often Gilbert’s syndrome. A blood test can confirm it. New yellowing with dark urine, pale stools or itch needs checking within days.
Evidence and more information
- Pathology Tests Explained (RCPA): Bilirubin
- Newsome et al, Gut 2018: Guidelines on the management of abnormal liver blood tests (Gilbert’s syndrome, isolated raised bilirubin)
- Fargo, Grogan and Saguil, American Family Physician 2017: Evaluation of jaundice in adults
- NICE NG12: Suspected cancer, recognition and referral (jaundice from age 40)
maladywise.com/blood-tests/high-bilirubin/