Total Bilirubin
Bilirubin is a yellow waste product made when your body breaks down old red blood cells, and your liver clears it. A result inside your report's range is reassuring. A raised result can cause jaundice — a yellowing of the skin and eyes — and has several causes, including a very common, harmless one called Gilbert syndrome.
Standard CareWhat is total bilirubin?
Bilirubin is an orange-yellow waste product that is made during the body's normal process of breaking down old red blood cells. When red blood cells reach the end of their lifespan (roughly 120 days), they are broken down and the haemoglobin (the oxygen-carrying protein inside them) is processed into bilirubin. The liver then takes up bilirubin, processes it into a water-soluble form (a step called conjugation — attaching bilirubin to another molecule so it can be excreted), and releases it into bile so it can leave the body through the gut. Total bilirubin is the combined measure of all bilirubin in the blood — both the unprocessed form (unconjugated bilirubin, sometimes called indirect) and the liver-processed form (conjugated bilirubin, sometimes called direct). When bilirubin builds up in the blood — either because too much is being made, the liver cannot process it fast enough, or bile cannot drain properly — it deposits in the skin and eyes, causing jaundice (the yellow discolouration most people associate with liver problems). Bilirubin is measured as part of Liver Function Tests (LFTs), alongside ALT, AST, GGT, ALP, and albumin.
Why is it tested?
Your GP may check bilirubin for several reasons. The most obvious is to look into visible jaundice (yellowing of the skin or the whites of the eyes), but it is also a routine part of an LFT panel that screens for liver conditions. In newborns it is checked on its own, since newborn jaundice is common in the first days of life. Bilirubin is also used to keep track of a known liver, bile duct, or blood condition that affects how red blood cells break down. And by comparing it with the other liver markers, your GP can tell different types of jaundice apart.
Reference range (Australia)
The AACB/RCPA Australasian Harmonised Reference Intervals specify 1–20 µmol/L for adults. The range printed on your own report is the authoritative figure for your result.
Reference intervals vary between laboratories. Always use the range printed on your own report.
What your result means
A low bilirubin result is not clinically significant. Your GP will focus on the overall LFT panel and your clinical picture.
An in-range bilirubin result is generally reassuring — it suggests bilirubin is being processed and excreted normally. Your GP reads it alongside the rest of the LFT panel to build the complete picture.
A raised bilirubin level causes jaundice when bilirubin deposits in the skin and eyes. The cause depends on where in the bilirubin pathway the problem lies. High levels of conjugated (direct) bilirubin suggest liver or post-liver problems, such as liver cell injury (like hepatitis — liver inflammation), intra-liver blockages (cholestasis — a slowdown or stoppage of bile flow inside the liver), or obstruction outside the liver (like gallstones or tumours compressing the biliary tree — the system of ducts that carries bile from the liver). High levels of unconjugated (indirect) bilirubin point to causes before the liver. By far the most common and reassuring is Gilbert syndrome (covered just below). Less commonly, they can reflect haemolysis (a haemolytic disorder, where too many red blood cells are broken down) or ineffective making of red blood cells. Gilbert syndrome deserves a reassuring mention: it is a very common, harmless inherited condition in which the liver is slightly slower at conjugating bilirubin. People with Gilbert syndrome may notice their bilirubin rises mildly during fasting, illness, or stress — but their liver enzymes (ALT, AST, GGT, ALP) remain normal. Gilbert syndrome is harmless and generally needs no treatment. If your bilirubin is mildly raised and your other liver markers are normal, your GP can confirm whether Gilbert syndrome is the explanation.
What can affect your result
Bilirubin can be affected at any stage of its production, processing, or excretion. Several things can raise it. Liver cell injury — from hepatitis (viral inflammation of the liver), alcoholic liver disease, or drug toxicity — leaves the liver less able to clear bilirubin. A blocked bile duct, from gallstones, tumours, or scarring, stops processed bilirubin draining into the gut. It can also rise before the liver is even involved. Haemolysis (a faster breakdown of red blood cells, from conditions such as haemolytic anaemia or certain inherited disorders) floods the system with more bilirubin than usual. And Gilbert syndrome — a very common, benign inherited variation in bilirubin processing — typically causes a mild, on-and-off rise. Fasting and dehydration can transiently raise bilirubin in people with Gilbert syndrome. Strenuous exercise can also cause a short-lived mild rise due to increased red blood cell breakdown. Certain medications can affect bilirubin levels. Your GP will consider your medication list when interpreting your result.
When to act
If your bilirubin is raised, your GP will look at the rest of your LFT panel to narrow down the cause. A raised bilirubin with abnormal ALT, AST, GGT, or ALP points towards a liver or bile duct cause; a raised bilirubin with a normal LFT panel is more suggestive of a pre-liver cause such as Gilbert syndrome or haemolysis (increased red blood cell breakdown). Mild, isolated bilirubin rises are often benign and your GP may simply monitor them over time. A significantly raised bilirubin — particularly with visible jaundice, dark urine, pale stools, or abdominal pain — warrants prompt attention and further investigation. If you have noticed yellowing of your skin or eyes, it is worth mentioning to your GP sooner rather than later, as jaundice can have a range of causes that are best assessed promptly. This page is general information and is not a substitute for advice from your GP.
Frequently asked questions
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