Bilirubin, indirect (unconjugated)

What it measures

Indirect bilirubin is calculated as total minus direct bilirubin. It rises when bilirubin is produced faster than the liver can conjugate it, or when conjugation itself is reduced.

Specimen and preparation

• Specimen: Serum or lithium-heparin plasma
• Tube: Gold top
• Preparation: Protect from light.

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Haemolytic anaemia
• Gilbert syndrome
• Neonatal jaundice
• Ineffective erythropoiesis (e.g. megaloblastic anaemia)
• Large haematoma resorption
• Crigler–Najjar syndrome

Method

Calculated: total bilirubin − direct bilirubin

Good to know

An isolated mild rise with normal enzymes and no haemolysis is usually Gilbert syndrome.

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