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Bilirubin

All information on Billirubin

At a glance

Bilirubin (Latin bilis “bile” and ruber “red”) is a yellow degradation product of the red blood pigment hemoglobin. Red blood cells have only a limited lifespan, so bilirubin is constantly produced and must be broken down. The presence of bilirubin in the blood is therefore normal, in the urine it occurs only in very small quantities. It provides the characteristic yellowing of urine.

Bilirubin is produced in the feeding cells (macrophages), which eliminate the old red blood cells. This takes place for the most part in the spleen, as this is where the old red blood cells are sorted out. But macrophages can also start releasing bilirubin elsewhere in the body. Especially after injuries in which red blood cells are destroyed, this happens directly on the spot. We can follow the process with the naked eye by tracking the color changes of a bruise.

Further information

The resulting bilirubin is metabolized via the liver and then transported into the intestine with bile. A small part is absorbed from the intestine back into the blood, reaches the kidney and is excreted in the urine.

The most common causes of higher levels of bilirubin in the urine are damage to the liver (e.g. severe cirrhosis of the liver, hepatitis) or blockages of bile flow by gallstones, inflammation or tumors. Even with severe hemolysis, an increased decay of red blood cells due to dissolution of the cell membrane, the bilirubin level rises sharply.

The diseases ensure that the resulting bilirubin cannot be metabolized in the liver in the case of liver disease or can not be transported into the intestine in the case of bilirubin. So it accumulates in the liver, gets back into the blood and is then alternatively excreted in the urine.

Sources

  • Roche Diagnostics Deutschland GmbH (2014): Kompendium der Urinanalyse. Urinteststreifen und Mikroskopie, 1-196
  • Lahnsteiner, E. et al. (2004): Harnanalyse – praktisch zusammengefasst, 2. Auflage
  • Hübl, W.: Bilirubin in the Urine – Overview, URL: https://www.med4you.at/laborbefunde/lbef3/lbef_bilirubin_im_harn.htm
  • Amboss:Urindiagnostik, URL: https://www.amboss.com/de/wissen/Urindiagnostik, Retrieved 18.06.2019
  • Sauerbaum et al. (2016): Medizinische Mikrobiologie und Infektiologie 8. Auflage Springer
  • Grabe et al. (2015): Guidelines on Urologic Infections. European Association of Urology (EAU)
  • Schmiemann, G. et al. (2010): Diagnose des Harnweginfekts In: Deutsches Ärzteblatt Band 107, Nummer 21, 361-7
  • Jocham, Miller (2007): Praxis der Urologie: Band 1, 3. Auflage Thieme
  • Althof, Kindler (2005): Das Harnsediment 7th edition. Thieme
  • Reiter, A. & Feichter, M. (2017): Bilirubin increases URL: https://www.netdoktor.de/laborwerte/bilirubin/erhoeht/
  • Neumeister, B. et al. (2009): Klinikleitfaden Labordiagnostik , Elsevier/Urban & Fischer Verlag, 4th edition
Status of information: 2022
Further information

The most common causes of higher levels of bilirubin in the urine are damage to the liver (e.g. severe cirrhosis of the liver, hepatitis) or blockages of bile flow by gallstones, inflammation or tumors.

Bilirubin levels also rise sharply in severe hemolysis, an increased decay of red blood cells due to dissolution of the cell membrane.

In the liver, the cells absorb bilirubin (without albumin part) and link it to the so-called glucuronic acid. This chemical change is called conjugation. The resulting so-called conjugated bilirubin is well water soluble. This is then excreted via the bile into the intestine.

In healthy people, there is virtually no conjugated bilirubin in the blood and therefore not in the urine.

In some diseases of the liver, the liver cells have problems excreting the conjugated bilirubin into the bile. It then accumulates in the liver cells and passes back into the blood. However, if the concentration of conjugated bilirubin in the blood increases, bilirubin also enters the urine. The conjugated bilirubin goes through the kidney filters into the urine without any problems. If the blood level of the conjugated bilirubin exceeds 2 mg/dl, bilirubin is excreted with the urine via the kidneys.

Inflammation of the liver (hepatitis), severe cirrhosis of the liver, poisoning and drug side effects are possible causes for conjugated bilirubin in the blood to increase.

Also if the outflow of bile into the intestine is impeded and a backlog occurs, conjugated bilirubin enters the blood.

For example, these are: inflammatory swelling of the bile ducts, gallstones, tumors or inflammation of the pancreas.

Liver damage is often free of complaints, so that they are often discovered “randomly” during a urine examination.

See also: blood in the urine, urobilinogen, kidney disease

Sources

  • Roche Diagnostics Deutschland GmbH (2014): Kompendium der Urinanalyse. Urinteststreifen und Mikroskopie, 1-196
  • Lahnsteiner, E. et al. (2004): Harnanalyse – praktisch zusammengefasst, 2. Auflage
  • Hübl, W.: Bilirubin in urine – Overview, URL: https://www.med4you.at/laborbefunde/lbef3/lbef_bilirubin_im_harn.htm, Retrieved 18.06.2019
  • Amboss:Urindiagnostik, URL: https://www.amboss.com/de/wissen/Urindiagnostik, Retrieved 18.06.2019
  • Sauerbaum et al. (2016): Medizinische Mikrobiologie und Infektiologie 8. Auflage Springer
  • Grabe et al. (2015): Guidelines on Urologic Infections. European Association of Urology (EAU), Retrieved 18.06.2019
  • Schmiemann, G. et al. (2010): Diagnose des Harnweginfekts In: Deutsches Ärzteblatt Band 107, Nummer 21, 361-7
  • Jocham, Miller (2007): Praxis der Urologie: Band 1, 3. Auflage Thieme
  • Althof, Kindler (2005): Das Harnsediment 7th edition. Thieme
  • Reiter, A. & Feichter, M. (2017): Bilirubin erhöht URL: https://www.netdoktor.de/laborwerte/bilirubin/erhoeht/, Retrieved 18.06.2019
  • Neumeister, B. et al. (2009): Klinikleitfaden Labordiagnostik , Elsevier/Urban & Fischer Verlag, 4th edition
Status of information: 2022
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