Bilirubin test: normal range, direct and indirect, and high results

A bilirubin test measures the yellow pigment left when old red blood cells are broken down. The liver collects it, processes it and sends it out in bile, so the level in blood reflects how fast red cells are broken down and how well the liver and bile ducts clear the pigment. A report usually gives total bilirubin and direct bilirubin, and indirect bilirubin is the difference between them.

What bilirubin measures

About 85 per cent of bilirubin comes from the haem in haemoglobin released by worn-out red cells. It travels in the blood in an unprocessed, insoluble form. The liver takes it up and attaches glucuronic acid to it, a step called conjugation, which makes it soluble so it can leave in bile.

That gives the three numbers on a report:

• Total bilirubin: all of it, processed and unprocessed.
• Direct bilirubin: the processed (conjugated) share, named for the way it reacts directly in the laboratory test.
• Indirect bilirubin: total minus direct, the unprocessed (unconjugated) share the liver has yet to handle.

In a healthy person, most of the bilirubin in blood is the unprocessed kind.

Bilirubin normal range

Bilirubin is reported in micromoles per litre (µmol/L) or in milligrams per decilitre (mg/dL), depending on the laboratory:

Result, adults	SI units	Conventional units
Total bilirubin	under 21 µmol/L	0.0 to 1.2 mg/dL
Direct bilirubin	0 to 5 µmol/L	0.0 to 0.3 mg/dL
Indirect bilirubin	total minus direct	total minus direct

The SI figures come from the UK harmonised adult range and one NHS laboratory, the conventional figures from Mayo Clinic Laboratories. Newborns and children have their own ranges. Ranges vary by laboratory and method, so read your result against the range on your own report.

What a high bilirubin usually points to

The split between direct and indirect is what makes a high total readable.

Mostly indirect

When the rise is mainly indirect and the other liver markers are normal, the commonest reason is Gilbert's syndrome, an inherited difference in how the liver processes bilirubin. The British Society of Gastroenterology puts it at 5 to 8 per cent of the population and says people with it should be fully reassured, because it is not linked to liver disease or ill health. Levels rise with fasting, dehydration, illness, intense exercise and menstruation, and many people find out from a routine blood test.

The other main reason is faster breakdown of red cells in the body (haemolysis), as in haemolytic anaemia or inherited red cell conditions such as G6PD deficiency. Here haemoglobin is often low as well.

Mostly direct

A raised direct bilirubin usually points to the liver or the bile ducts: liver cell disease such as hepatitis, or bile not draining because of a blockage such as a gallstone. It typically comes with raised liver enzymes, and because processed bilirubin dissolves in water it can also reach the urine. Rare inherited conditions, Dubin-Johnson and Rotor syndromes, raise direct bilirubin too.

What a doctor typically looks at next

For an isolated, mostly indirect rise, British guidance suggests repeating the test on a fasting sample with a full blood count and a direct and indirect split. In Gilbert's syndrome the total should rise further on fasting, from the indirect part, with no anaemia. If there is anaemia, a doctor looks for haemolysis with a reticulocyte count, lactate dehydrogenase and haptoglobin, and an unconjugated level above 40 µmol/L points towards rarer inherited conditions. For a direct rise, the liver enzymes and an ultrasound of the liver and bile ducts are the usual next steps.

A low bilirubin

MedlinePlus notes that a low bilirubin is not usually a cause for concern, and lists some antibiotics, birth control pills, sleeping pills and seizure medicines among possible reasons.

What moves bilirubin

• Fasting. Going without food raises indirect bilirubin in people with Gilbert's syndrome, which is why doctors use a fasting repeat test.
• Illness, dehydration and intense exercise, which can tip levels up in Gilbert's syndrome. In one weightlifting study, though, bilirubin stayed within range while ALT and AST rose.
• Medicines. Some raise bilirubin and some lower it. Mayo Clinic Laboratories notes that drugs which compete for binding sites on albumin, such as penicillin and aspirin, can lower the measured level.
• Light. Bilirubin breaks down in light, so laboratories protect samples from it; one left in strong light can read falsely low.
• Haemolysis in the tube. Red cells bursting after the draw interfere with the test and can give falsely low results; one study saw meaningful shifts once haemolysis was moderate.

Preparing for the test

MedlinePlus notes that you may be asked to fast for several hours. Because fasting itself raises bilirubin in Gilbert's syndrome, it helps to note how long you fasted and whether the test fell during Ramadan. Mention medicines, supplements and any recent illness; MedlinePlus advises against stopping any medicine unless your doctor tells you to. Our guide to what to expect from a comprehensive blood test covers the rest of the preparation.

How Clare's panel handles bilirubin

Clare's panel includes total bilirubin and direct bilirubin, both measured by the lab. Clare calculates indirect bilirubin from them:

Indirect bilirubin = total bilirubin minus direct bilirubin

The direct test also picks up delta bilirubin, a processed form bound to albumin with a half-life of about 21 days, so the calculated indirect figure is a close estimate rather than a separate measurement. The urine test in the panel adds Urine Bilirubin and Urobilinogen, two later steps in the same pathway.

Bilirubin in the UAE

Two local facts shape how a bilirubin result is read here. G6PD deficiency, an inherited condition in which red cells break down early after triggers such as certain infections, some medicines or fava beans, is common in the UAE. Newborn screening data from 20 hospitals and laboratories in Abu Dhabi, Dubai, Sharjah and Fujairah found it in about 5.3 per cent of 29,290 babies screened from 2021 to 2023, more than any other condition screened for. An episode of red cell breakdown pushes indirect bilirubin up.

The second is Ramadan. Fasting is a recognised trigger for higher bilirubin in Gilbert's syndrome, so a raised indirect bilirubin in a sample taken while fasting is worth reading with that in mind. In healthy adults more broadly, a 2021 review led from the University of Sharjah found small and inconsistent changes in bilirubin across Ramadan.

Price

Bilirubin is usually sold within a liver function test. When we read public prices on 11 October 2026, a liver function test cost from 89 to 1,100 at six UAE providers. The top figure was a wider package that adds a hepatitis B test; the five standard liver panels ran from 89 to 199. Most listings did not say whether VAT was included, and home collection can add a fee: one lab charged for it on smaller orders.

Related tests

Bilirubin is one part of the Liver function test. Read it with Alanine Aminotransferase (ALT) and Alkaline Phosphatase (ALP) for the liver side, Hemoglobin for the red cell side, and Urine Bilirubin.

Why bilirubin means more over time

Bilirubin is one of the markers where history explains a single number. Someone with Gilbert's syndrome may see a mildly raised indirect bilirubin come and go across years of tests, higher after fasting or illness, with normal liver enzymes each time, and that recurring pattern is itself informative. A direct bilirubin that rises between tests, especially alongside ALP or GGT, is different and worth raising with a doctor. When Clare opens, each member's results will sit in one health account, with each marker's trend over time.

Clare is opening with a waitlist at clare.health.