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# Gilbert syndrome

A benign inherited condition in which the liver conjugates less bilirubin; it causes mild jaundice with fasting, stress or infection.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Liver](https://durgical.com/en/anatomy/liver/)
- [Sclera](https://durgical.com/en/anatomy/sclera/)

## In biochemistry

- [Liver function tests: reading the pattern](https://durgical.com/en/biochemistry/topics/liver-function-tests-reading-the-pattern/)
- [Uronic acid pathway](https://durgical.com/en/biochemistry/topics/uronic-acid-pathway/)
- [UGT1A1 (bilirubin UDP-glucuronosyltransferase)](https://durgical.com/en/biochemistry/enzymes/ugt1a1/)
- [Bilirubin](https://durgical.com/en/biochemistry/molecules/bilirubin/)
- [Glucuronidation](https://durgical.com/en/biochemistry/topics/glucuronidation/)

## In the clinical exam

- [Jaundice: prehepatic, hepatic and posthepatic](https://durgical.com/en/clinical-exam/jaundice-prehepatic-hepatic-and-posthepatic/)

## In physiology

- [Bile and the enterohepatic circulation](https://durgical.com/en/physiology/bile-and-the-enterohepatic-circulation/)
- [Functions of the liver](https://durgical.com/en/physiology/functions-of-the-liver/)

## What it is

Mild, fluctuating unconjugated hyperbilirubinemia from reduced expression of liver UGT1A1, without hemolysis or liver disease.

## Who gets it

Very common: it affects about 3–7 % of the population; it is found in adolescence or adulthood, often on routine tests. More evident in men.

## Causes

- UGT1A1*28 variant (extra TA repeats in the promoter), usually on both alleles
- Other UGT1A1 variants, more common in Asia

## Risk factors

- Fasting or a very low-calorie diet
- Infections, strenuous exercise, menstruation, lack of sleep

## Pathophysiology

UGT1A1 works at about 30 % of normal. Indirect bilirubin builds up slightly, especially when fasting raises the load or slows conjugation. Liver tests are normal and there is no liver damage.

## Symptoms and signs

- Mild, intermittent yellowing of the sclerae
- Most have no other symptoms
- Sometimes fatigue or vague abdominal discomfort

## Red flags

- Raised direct bilirubin or abnormal liver enzymes (suggests another cause)
- Anemia or high reticulocytes (hemolysis)

## Diagnosis

**Clinical**
Mild recurrent jaundice brought on by fasting or illness, with a normal physical examination.

**Tests**
Mildly raised indirect bilirubin (usually below 3–4 mg/dL), normal direct bilirubin, normal transaminases and alkaline phosphatase; blood count and reticulocytes to rule out hemolysis; UGT1A1 genotype if in doubt.

**Imaging**
Not needed; [liver](https://durgical.com/en/anatomy/liver/) ultrasound only if other tests are abnormal.

## Treatment

**Conservative**
No treatment is needed; explaining that it is benign avoids unnecessary investigations

**Follow-up**
Caution with drugs cleared by UGT1A1, such as irinotecan

## Complications

- Greater irinotecan toxicity
- Possibly more gallstones when hemolysis coexists

## Prognosis

Excellent; life expectancy is normal.

## Test yourself

Think of the answer, then tap the question to see it.

## Which bilirubin fraction rises in Gilbert syndrome?

Unconjugated (indirect) bilirubin.

## What triggers jaundice in Gilbert syndrome?

Fasting, infection, stress, strenuous exercise and menstruation.

## Which gene and variant most often cause Gilbert syndrome?

UGT1A1, promoter variant *28 (extra TA repeats).

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## Related conditions

- [Crigler-Najjar syndrome](https://durgical.com/en/conditions/crigler-najjar-syndrome/)
- [Neonatal jaundice](https://durgical.com/en/conditions/neonatal-jaundice/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Gilbert syndrome: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/gilbert-syndrome/) (MedlinePlus, US National Library of Medicine, 2026); [UGT1A1 gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/ugt1a1/) (MedlinePlus, US National Library of Medicine, 2026); [Bilirubin blood test: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003479.htm) (MedlinePlus, US National Library of Medicine, 2026).

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Source: https://durgical.com/en/conditions/gilbert-syndrome/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/gilbert-syndrome/