Urea is the first organic compound synthesized from inorganic sources. With the synthesis of urea from potassium cyanide and ammonia, the German chemist Friedrich Wöhler proved in 1828 that no organism is needed in the production of organic matter.
Thus the mysterious border between organic and inorganic chemistry disappeared. The chemical name for urea is carbonic acid diamide. It contains two amino groups and one CO double bond in the molecule. The empirical formula of urea is CH4N2O.
Urea is a non-toxic, white and crystalline substance with hygroscopic (water-attracting) properties that has the greatest importance as a fertilizer in agriculture. In addition to carbon dioxide, water and minerals, it is also one of the most important metabolic end products of the body.
The organism produces urea via the so-called urea cycle. Finally, the amino and carboxyl groups of the amino acids are used in this synthesis for the synthesis of urea.
The remaining nitrogen-free compound is further degraded to carbon dioxide and water or returned to the metabolism. The amino groups can also be re-integrated into the material cycle. In the form of urea, nitrogen is no longer available for building up endogenous substances and is therefore excreted. The nitrogen balance can only be balanced by protein-containing foods. Although the concentration of urea in urine can vary greatly depending on nutritional status and physical condition, without being able to predict the state of health, prolonged over or under concentration indicates health problems.
Too much urea concentration can occur with increased protein degradation by catabolic diseases such as cancer, intense inflammatory processes or necrosis. Filtration disorders of the kidneys also lead to increased urea levels because the ammonia generated by the metabolism is no longer properly recycled into the material cycle. As an alternative, only its conversion into urea remains.
Otherwise, the increased ammonia level would lead to poisoning of the body. Too low urea levels indicate a low-protein diet or disorders with absorption disorders, such as celiac disease. The urea analysis can only lead to a meaningful diagnosis in connection with other laboratory values.
Medically, urea is important both analytically and therapeutically. The analytical significance results from the already mentioned indicator function for various diseases.
A function for the possible treatment of internal diseases does not play urea. But it has properties that its application z. B. in cosmetics make interesting. So urea is hygroscopic, so attracting water. It is contained in sweat to soften the skin. If urea is missing, the skin becomes dry and tends to develop eczema and itching. Therefore, urea is included in many creams to provide the skin with sufficient moisture.
In general, urea creams contain 2 to 20 percent urea. Another application for urea results from its keratolytic (corneal dissolving) effect. 40% urea formulations are able to dissolve corns and calluses. Furthermore, urea-containing creams are used in atopic dermatitis and psoriasis. A particularly interesting application is the use of nail fungus, wherein the nail is softened to remove the fungus so.
Urea-containing creams should not be used in case of hypersensitivity of the skin to urea. This also applies to inflamed and injured skin. Eye and mucous membrane contact with urea-containing agents should also be avoided. There are no experiences with the treatment of children.
Therefore, the use of urea-containing substances is not recommended. Hypersensitivity reactions are rare. However, if they do, it can cause burning, itching or redness of the skin. Sometimes urea increases the release of drugs from other creams and ointments, and its effects can be increased.