Bilirubin

Also written as: total bilirubin, TBIL

A yellow pigment from the normal recycling of red blood cells, processed by the liver and removed in bile.

What it measures

The amount of bilirubin, a yellow pigment produced when old red blood cells are broken down and recycled. The liver processes bilirubin and passes it out through bile, so the blood level reflects the balance between red cell turnover and liver clearance.

Why a doctor orders it

It is part of standard liver panels and is checked when jaundice (yellowing of the skin or eyes), liver conditions, bile duct blockage, or unusually fast red cell breakdown is being considered. Labs can split it into direct and indirect forms, which point to different parts of the pathway.

What is generally associated with a higher result

Broadly associated with liver conditions, blockage of the bile ducts, and faster than normal breakdown of red blood cells. A mild isolated rise is also very commonly due to Gilbert syndrome, a harmless inherited trait affecting a meaningful share of the population, especially after fasting or illness.

What is generally associated with a lower result

Low values are generally not pursued.

Everyday things that move this number

Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:

Fasting or skipping meals before the draw, which raises it in many people
Gilbert syndrome, a common and harmless inherited trait
Vigorous exercise before the draw
Exposure of the sample to light, which lowers it
Some common medications

Questions to take to your appointment

Was this split into direct and indirect bilirubin, and which portion is responsible?
Could Gilbert syndrome explain a mild isolated rise?
Could fasting before the draw have influenced this result?

Build a printable questionnaire with your own results →

Where to read more

MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .

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