Unconjugated Bilirubin

Unconjugated (indirect) bilirubin is the fraction that the liver has not yet processed. It rises when red cells break down faster than the liver can clear them (haemolysis) or when the liver's bilirubin-conjugating enzyme is underactive, as in Gilbert's syndrome — a benign genetic variant present in 5–10% of the population.

Gilbert's syndrome (benign, most common cause of mildly elevated values), haemolysis from any cause (haemoglobinopathies, autoimmune, drug-induced), neonatal jaundice. Combined elevation with abnormal liver enzymes indicates hepatobiliary pathology.

Gilbert's pattern is asymptomatic aside from mild yellowing of the eyes during fasting, illness, or intense exercise. Frank haemolysis produces fatigue, pale skin, dark urine, and exertional breathlessness.

Adequate hydration and regular meals blunt the fasting-related yellow eye tint in Gilbert's. Antioxidant-rich foods support red-cell integrity.

Prolonged fasting and dehydration exaggerate Gilbert's-pattern elevations but are not harmful. Avoid drugs known to trigger haemolysis in G6PD-deficient individuals (if relevant).