Creatinine is a degradation product of the acid creatine. Creatine is needed for the energy supply of the muscles. In the kidneys, liver and pancreas, creatine is formed from the amino acids glycine, methionine and arginine. Every day, about 1.5 to 2% of the creatine is excreted as creatinine by the kidneys with the urine.
Creatinine
All information on the subject of creatinine
At a glance
Not every person excretes the same amount of creatinine. The amount depends on his muscle mass and kidney function. The creatinine value can therefore be used to assess kidney function and to track the course of kidney disease.
Further information
For men, values between 0.5mg/dl and 1.1 mg/dl are considered normal, for women normal values are between 0.5mg/dl and 0.9mg/dl.
Too low creatinine levels have no medical significance.
If the creatinine levels are increased, this may indicate a disturbed function of the kidneys. Injuries to the muscles, muscular dystrophy or inflammation of the skin and muscles (dermatomyositis, polymyositis) are also possible causes. After exercise, seizures and after injections into the muscles (e.g. vaccinations), the values may also be increased.
The measurement value of urine creatinine is not considered in isolation, but in connection with other laboratory values. Among other things, it is a component of creatinine clearance and the albumin-creatinine quotient.
Creatinine clearance records the filter and detoxification performance of the kidneys and is determined to better assess kidney function. Some diseases, such as diabetes mellitus or high blood pressure, often also lead to damage to the kidneys. Therefore, especially in such known pre-diseases, kidney values should be examined regularly.
The albumin-creatinine quotient is used to estimate protein excretion. This must always be set in relation to another size. A sole specification of the excreted protein does not make sense, as this is too dependent on the dilution state of the urine. Therefore, the excreted albumin is either set in relation to the volume of urine or related to the relatively constant creatinine. Since the first option requires a 24-hour collection urine measurement, the second method has become established.
Athletes, especially strength athletes, often take creatine as a dietary supplement to achieve an increase in strength endurance. A positive effect on muscle building and performance is possible, but not with every athlete. As a natural nutrient, creatine is mainly found in fish and meat, plant-based foods are less creat-containing.
Sources
- Internists on the net: creatinine, URL: https://www.internisten-im-netz.de/mediathek/blutbild-erklaerung/kreatinin.html
- Huppelsberg, J. & Walter, K. (2013): Kurzlehrbuch Physiologie. Georg Thieme Verlag, 4th edition
- Antwerpes, F.: Urine creatinine, URL: https://flexikon.doccheck.com/de/Urinkreatinin
- Lahnsteiner, E. et al. (2004): Harnanalyse – praktisch zusammengefasst, 2. Auflage
- Winemaker, C. & Pohanka, E. (2006): Sinn und Unsinn der Kreatinin-Bestimmung Nephro Script. 9. 6-10
- Gressner, A. M. & Arndt, T. (2007): Lexikon der Medizinischen Laboratoriumsdiagnostik. Springer Verlag, 1st edition
- Greten, H. et al. (2010): Innere Medizin Georg Thieme Verlag, 13th edition
- Kuhlmann, U. et al. (2008): Nephrologie Georg Thieme Verlag, 5th edition
