Nitrogen balance

The nitrogen balance is in medicine a laboratory value, the basis of which is a fairly reliable indicator of protein metabolism can be assessed. He indicates in what proportion of nitrogen intake and output are in the organism.

Basics

Proteins consist essentially of many amino acids strung together. Each of these amino acids contains at least one nitrogen atom. If now, for example, proteins extracted from the muscles, they form individual amino acids. In their metabolism drops of nitrogen that must be excreted by the kidney. For this purpose, it is first converted in the liver to urea. Nitrogen balance is now referred to the difference between consumed and excreted amount of nitrogen.

Where in the record, particularly in the muscles more protein degraded as set up by the body, which is the case for example in times of famine ( catabolic metabolism), the nitrogen balance is negative. The body loses as nitrogen compounds by the protein and amino acids thereby reducing.

If a man, however, for example, 10 grams of nitrogen, there is only 5 grams off, so there is a positive nitrogen balance. This is the case, for example, in growth or in regeneration times for strength athletes. It is taken up more nitrogen than given, and thus more protein - reduced to a.

This can be seen also that the body undergoes a metabolic crisis (eg by prolonged fasting or illness ). Towards the end of the crisis, it swings back into the building ( anabolic ) metabolism, in which proteins are built up again.

The protein catabolism is of particular relevance to humans. It can build up from storage fat no glucose ( the other way around very well ), but he needs for the high-energy fat loss always glucose, otherwise the energy balance deteriorates. In addition, the brain and the red blood cells rely on glucose. In a hypo may even lead to acidosis of the blood. Liver cells but are able to operate gluconeogenesis, that produce glucose. In particular the protein components, the amino acids are converted into glucose.

In detail, the liver cells divide from the amino ( nitrogen) ends with the simple amino acids. From the remaining carbon skeleton arise intermediates of the citrate cycle and " Zuläufer " gluconeogenesis and fatty acid synthesis. Here, the aforementioned nitrogen is obtained in the form of ammonia, which is packaged in urea and excreted through the kidney.

Swell

• Nutritional Medicine: After the Curriculum Nutritional Medicine of the German Medical Association; ISBN 978-3-13-100293-8
• Hermann Hager, Hubert Snowman, Gisela Wurm; Handbook of pharmacy practice; ISBN 978-3-540-58958-7
• Werner Müller- Esterl: Biochemistry: An Introduction