Proteins

All information on proteins

At a glance

Healthy urine should contain only very small amounts of dissolved proteins.

The examination of urine for proteins is mainly used for the early detection of kidney damage.

The kidneys filter unnecessary substances from the blood to dispose of with the urine. The kidneys hold back proteins in the blood almost completely.

Too large proteins do not fit through the “filter”. Smaller proteins are returned to the blood by the kidneys after filtering. However, small amounts of protein can also occur in the urine of healthy people.

If there are increased amounts of protein in the urine (more than 150mg in 24 hours), it is called proteinuria.

Often proteins in the urine are diagnosed during a routine urine examination as part of a screening. In urine test strips, the protein albumin is mainly recorded.

For more information

The following kidney diseases are usually hidden behind a proteinuria:

  • Kidney inflammation
  • Kidney damage
  • Diabetes with kidney involvement

 

Diseases that do not come directly from the kidneys can also be the reason for increased protein levels in the urine. These include, for example:

  • Hypertension
  • various heart diseases
  • rheumatoid arthritis
  • Tuberculosis
  • Malaria

 

Other possible causes of short-term proteinuria are urinary tract infections. Typical symptoms include burning and discomfort when urinating, as well as frequent urge to urinate.

If proteinuria occurs in the first half of pregnancy, this may indicate a pre-existing urinary tract or kidney disease. In the second half of pregnancy, pregnancy poisoning (preeclampsia) is a possible cause and should be clarified immediately.

Persistent proteinuria can be caused by chronic renal failure . This is the slowly advancing loss of kidney function over months and years . Chronic renal failure often goes unnoticed for a long time, as there are no pronounced symptoms at first. It usually develops in a creeping way.

In the advanced stage of renal failure, a complex clinical picture is revealed, which also affects other organ systems.

Persistent fatigue, itching, nocturnal urination, shortness of breath and pale skin color are further signs of chronic kidney failure.

It is very often caused by inadequately treated high blood pressure or type 1 or type 2 diabetes mellitus. But hereditary kidney disease or chronic kidney inflammation can also be considered as a cause.

Sources

  • Roche Diagnostics Deutschland GmbH (2014): Kompendium der Urinanalyse. Urinteststreifen und Mikroskopie, 1-196
  • Nagel, G. & Gehring, F. (2019): Eiweiß im Urin (Proteinurie): Wann ist das bedenklich?,URL: https://www.onmeda.de/symptome/eiweiss-im-urin.html, Retrieved 18.06.2019
  • Lahnsteiner, E. et al. (2004): Harnanalyse – praktisch zusammengefasst, 2. Auflage
  • Deximed (2017): Proteinurie (Eiweiß im Urin), URL: https://deximed.de/home/b/niere-harnwege/patienteninformationen/was-kann-das-sein/proteinurie-eiweiss-im-urin/, Retrieved 18.06.2019
  • Hübl, W.: Eiweiß im Harn (Proteinurie) – Übersicht, URL: https://www.med4you.at/laborbefunde/lbef3/lbef_eiweiss_im_harn.htm, Retrieved 18.06.2019
Status of information: Autumn 2019