Empeiria

Bilirubin, total

Also known as TBIL, total bilirubin, bili

C₃₃H₃₆N₄O₆ small molecule

LOINC 1975-2 code verified serum mg/dL

unverified These explanations are written to be easy to read and have not yet been checked against a source. The ranges and measurement notes on this page show theirs.

definition unverified

The yellow-orange pigment left over when old red blood cells are broken down. The liver processes it and sends it out in bile.

Breakdown product of heme, conjugated in the liver and excreted in bile. Elevation reflects haemolysis, impaired conjugation, or biliary obstruction.

if high unverified

There are three broad reasons. Red cells may be breaking down faster than usual. The liver may not be processing it. Or the drainage out of the liver may be blocked. There is also a harmless inherited version called Gilbert syndrome. About three in every hundred people have it. Their level rises when they are unwell or have not eaten, and nothing needs to be done.

There are three broad reasons. Red cells may be breaking down faster than usual. The liver may not be processing it. Or the drainage out of the liver may be blocked. There is also a harmless inherited version called Gilbert syndrome. About three in every hundred people have it. Their level rises when they are unwell or have not eaten, and nothing needs to be done.

No clinical version written yet.

caveats unverified

You cannot see any yellowing until the level is about twice the upper limit. So a slightly raised number usually shows no outward sign at all.

You cannot see any yellowing until the level is about twice the upper limit. So a slightly raised number usually shows no outward sign at all.

No clinical version written yet.

What this substance is

formula
C₃₃H₃₆N₄O₆
mass
584.673 g/mol
monoisotopic
584.26348
charge
0
InChIKey
BPYKTIZUTYGOLE-IFADSCNNSA-N
ChEBI
CHEBI:16990
CAS
635-65-4

Drawn from ChEBI's own curated 2D drawing, accepted only after its InChIKey, formula and charge matched the ChEBI release. Nothing here is hand-entered. Two masses are given because they answer different questions: the average is natural-abundance weighted and drives unit conversion; the monoisotopic value uses only the commonest isotope of each element and is what mass spectrometry measures.

3D model · Bilirubin, total

Generated by RDKit from ChEBI's verified structure, and accepted only because its own 3D geometry reproduces ChEBI's InChIKey. A flexible molecule takes many shapes; this is one low-energy one. Drag to rotate, scroll to zoom.

Reference ranges

Checking your own result against this range needs the running application; this is a static copy. Nothing you type anywhere in Empeiria is ever sent to a server.

This open edition shows a range only where a public-domain or openly licensed source states one, and none does for this marker yet. Compare your result with the range printed on your own lab report.

How it is measured

In practice

A health worker takes a small blood sample from a vein in your arm with a needle. For a newborn baby, the heel is cleaned and pricked with a small needle to collect a few drops of blood. Your provider may ask you not to eat or drink for several hours before the test.

Adults: venipuncture; serum, lithium heparin plasma or K2-EDTA plasma are acceptable. Newborns: heel stick. The specimen should be protected from light, since bilirubin degrades with prolonged light exposure; separated serum or plasma should be removed from cells within one hour. Bilirubin can also be tested in urine.

Before the test

  • Fast (no food or drink) for several hours if your provider tells you to.
  • Tell your provider about everything you take, but do not stop any medicine unless your provider tells you to.

Where: laboratory

Sources: Bilirubin Blood Test, MedlinePlus (U.S. National Library of Medicine); NHANES 2017-2018 Laboratory Procedure Manual, Total Bilirubin (CDC National Center for Health Statistics) cited · not yet checked by a person

In the lab

enzymatic colorimetric

Diazo (Jendrassik-Grof)

The pigment is made to react with another chemical to form a coloured compound. Adding a helper substance lets the lab measure the part that is bound and the part that is not, separately.

Bilirubin couples with diazotised sulfanilic acid to form azobilirubin. An accelerator is required for the unconjugated fraction, which is how total and direct bilirubin are distinguished.

  • Read by: Absorbance at 600 nm

What can throw it off

  • Light: bilirubin is photodegraded, so samples must be protected from it.
  • Haemolysis

Protect from light; wrap or use amber tubes.

Why labs disagree: Total bilirubin varies between analysers. In an eight-platform comparison on serum from healthy volunteers it was rated "red" (bias probably prevents one shared reference interval), with the differences most apparent at low concentrations. Calibration adds variation: imprecision persists depending on whether calibrators use a human or bovine serum matrix, and bilirubin reacts incompletely and unpredictably in bovine serum.

Sources: Koerbin G et al. Bias Assessment of General Chemistry Analytes using Commutable Samples. Clin Biochem Rev 2014;35:203-211 (PMC4310060); Measurement and clinical usefulness of bilirubin in liver disease. Adv Lab Med 2021 (PMC10197288) cited · not yet checked by a person

What it reports on

Associated symptoms

When high

Conditions this marker features in

When high
  • high A harmless inherited cause of high bilirubin · defining
    Mildly raised, mostly as unconjugated bilirubin, usually below 2 mg/dL, with nothing else abnormal. It rises further on a fasting sample.
  • high Anaemia from red cells breaking down too fast · supportive
    Bilirubin comes from broken-down red cells, so it rises in haemolytic anaemia. The rise is in the unconjugated (indirect) part. Gilbert syndrome and liver disease can also raise it.
  • high Blocked or slowed bile flow · supportive
    Bilirubin can be raised in cholestasis, mainly at more advanced stages, but it is also raised in liver-cell injury, so it does not tell the two apart.
  • high Liver damage from alcohol · supportive
    Part of the consensus criteria for alcohol-related hepatitis: bilirubin above 3 mg/dL (about 50 µmol/L). A high level also marks more advanced disease.
  • high Low vitamin B12 · supportive
    Red-cell precursors break down inside the bone marrow, which can raise bilirubin (the indirect form) and LDH, so the picture can look like haemolysis.

Ordered as part of

cmp · hepatic