Total bilirubin
Chemistry ·Also called: TBIL, total bili, bilirubin total, jaundice, icterus
What it is
Bilirubin is a waste product of haemoglobin recycling. The liver takes it up, modifies it, and excretes it in bile. Total bilirubin is what is measured on most panels; a laboratory can split it into direct and indirect fractions to help localise the problem.
Why your vet measures it
Bilirubin is one of the few lab values with a visible counterpart. Once it climbs far enough, the whites of the eyes, the gums and the inside of the ears turn yellow — jaundice. Finding it on a panel before the yellowing is obvious buys time.
What a high result can mean
- Destruction of red blood cells, such as immune-mediated haemolytic anaemia or a toxin
- Liver disease severe enough to impair processing — hepatitis, lipidosis, cirrhosis, tumours
- Obstruction of bile flow by a stone, a mass, or swelling from pancreatitis
- Sepsis, which can raise bilirubin without a primary liver problem
- Prolonged fasting in cats
What a low result can mean
- Not clinically significant
Dogs and cats differ
In cats, jaundice with a history of not eating raises hepatic lipidosis high on the list, and it is an emergency — the liver deteriorates quickly without nutritional support. In dogs, sudden jaundice with pale gums points first at red cell destruction.
Questions worth asking your vet
- Is my pet's anaemia panel normal — could red cell destruction explain this?
- Do we need imaging to check for a blockage of the bile duct?
- Are the gums or eyes visibly yellow yet?
Related terms
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