Yellow pigment from red-cell breakdown; high levels can cause jaundice.
What it is
Total bilirubin in µmol/L sums conjugated and unconjugated forms. Mild isolated rises may be Gilbert’s syndrome, a common, benign conjugation variant.
Bilirubin is produced from haem breakdown (mainly old red cells). The liver conjugates it for bile excretion. Total bilirubin in µmol/L is the routine first report; split bilirubin is added when needed.
Why it matters
Higher bilirubin with abnormal liver enzymes or pale stools/dark urine needs prompt review. Fasting, illness, and haemolysis can raise bilirubin. Jaundice is clinical, not DIY.
This guide is educational only and cannot diagnose you. Discuss results, especially anything outside your laboratory’s reference interval, or that does not match how you feel, with a GP or other appropriately qualified clinician.
How it affects the body
Bilirubin is processed by the liver for excretion in bile. Accumulation stains sclera and skin yellow when levels are high enough.
Unconjugated bilirubin travels on albumin to the liver; conjugated bilirubin appears in urine when refluxed to blood in cholestasis (dark urine). Severe neonatal jaundice is a different clinical domain from adult Gilbert’s-type rises.
For athletes
Hard training plus fasting around weigh-ins can unmask Gilbert’s-type rises: usually harmless if enzymes are otherwise fine, but confirm with a clinician rather than assuming.
Fasted race-week bloods can unmask Gilbert’s syndrome (harmless if enzymes otherwise settle). Jaundice, pale stools, or dark urine still need prompt medical care.
