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Gilbert's syndrome

SNOMED: 27503000581 words•Updated 03/03/2026

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Exam Tips

Think Gilbert's in a well patient with isolated unconjugated bilirubin rise, normal LFTs, and no haemolysis.
Intermittent jaundice triggered by fasting/illness/exertion/sleep loss is a classic OSCE clue.
Red flags against Gilbert's: dark urine, pale stools, pruritus, persistent pain, hepatosplenomegaly, abnormal transaminases/ALP.
Diagnosis is by exclusion; fasting provocation tests are not routinely recommended in primary care.
Prescribing viva point: avoid gemfibrozil-statin combination; if fibrate needed with a statin, fenofibrate is generally preferred with caution.

Definition

Gilbert's syndrome is a common inherited disorder of bilirubin handling that causes isolated, mild, intermittent unconjugated hyperbilirubinaemia in the setting of otherwise normal liver function and no haemolysis. It usually reflects reduced hepatic UGT1A1 (UDP-glucuronosyltransferase) activity, so patients may develop self-limiting jaundice during physiological stress (for example fasting, dehydration, illness, or sleep deprivation) without progression to chronic liver disease.

Pathophysiology

Unconjugated bilirubin is generated from haem breakdown and normally conjugated in hepatocytes by UGT1A1 before biliary excretion. In Gilbert's syndrome (often autosomal recessive UGT1A1 variants), hepatic conjugation capacity is reduced by about 60-70%, producing fluctuating rises in unconjugated bilirubin (typically mild) while other liver enzymes remain normal and haemolysis is absent. Bilirubin may rise transiently when bilirubin production increases or hepatic handling is stressed (fasting, infection, exertion, alcohol, surgery). See Figure: bilirubin metabolism pathway in standard hepatology texts (e. g, Oxford Textbook of Medicine, hepatology chapter).

Risk Factors

Family history of Gilbert's syndrome (inherited UGT1A1 defect, usually autosomal recessive)
Male sex (higher prevalence than females)
Type 1 diabetes mellitus (reported increased prevalence)
Precipitating stressors: fasting/dieting, dehydration, intercurrent infection, surgery, heavy exertion, alcohol excess, sleep deprivation

Clinical Features

Symptoms

Usually asymptomatic
Intermittent mild jaundice (often scleral icterus), especially during stress/illness/fasting
Symptoms such as pruritus, pale stools, dark urine, persistent abdominal pain are atypical and suggest alternative pathology

Signs

Mild jaundice during episodes
Possible signs of trigger (e. g, dehydration, intercurrent infection)
No hepatosplenomegaly
No stigmata of chronic liver disease

Investigations

Liver blood tests including bilirubin fractionation:Isolated unconjugated hyperbilirubinaemia (often <68-85 micromol/L), with otherwise normal ALT/AST/ALP and albumin

Repeat bilirubin measurements over time:Intermittent/recurrent unconjugated bilirubin elevation consistent with self-limiting episodes

Full blood count, reticulocyte count, blood film, LDH (± haptoglobin):No evidence of haemolysis

Clinical assessment for liver disease and red flags:No features suggesting chronic liver disease or obstructive/cholestatic jaundice

Sample handling:Protect bilirubin sample from light (e. g, wrapped tube/envelope) to reduce pre-analytical error

Specialist genetic testing (UGT1A1), if diagnostic uncertainty:May confirm inherited conjugation defect; rarely required in routine practice

Management

Lifestyle Modifications

Reassure: benign condition, no routine treatment or regular monitoring needed, normal life expectancy
Explain common triggers and reduce exposure where possible (avoid prolonged fasting, maintain hydration, optimise sleep, moderate alcohol intake within UK recommendations)
Advise to seek review if jaundice is more severe, prolonged, or different from usual pattern
Encourage patients to tell healthcare professionals their diagnosis to avoid unnecessary repeat investigations

Pharmacological Treatment

Condition-specific therapy

No routine pharmacological treatment is indicated for Gilbert's syndrome itself.

Lipid-lowering drugs requiring caution

Gemfibrozil 600 mg twice daily (typically 30 minutes before morning and evening meals)
Simvastatin 10-40 mg once nightly
Atorvastatin 10-80 mg once daily
Rosuvastatin 5-40 mg once daily
Fenofibrate 200 mg once daily (safer fibrate option than gemfibrozil if a fibrate is required)

Gemfibrozil can worsen hyperbilirubinaemia via glucuronidation effects and increases statin exposure; gemfibrozil + any statin is contraindicated due to high myopathy/rhabdomyolysis risk. If statin therapy is needed, use cautious dosing and monitor for intolerance (myalgia, CK rise, LFT change). In overdose settings, note concern for hepatotoxicity with paracetamol.

Complications

No progression to chronic liver disease or liver failure
Recurrent but self-limiting jaundice episodes causing anxiety or unnecessary investigations
Potential increased adverse drug effects with glucuronidated medicines (notably gemfibrozil-statin toxicity risk)

Prognosis

Excellent. Hyperbilirubinaemia is typically mild and intermittent, episodes settle within days, and overall survival is normal; observational data also suggest possible cardiometabolic and mortality benefits associated with mildly raised unconjugated bilirubin.