Urea

The main end product of the protein metabolism is formed in the liver and can be excreted with the urine.

Urea is the end product of the urea cycle, which serves in the human body to detoxify the metabolic toxin ammonia produced in amino aciddegradation (building blocks of proteins). Ammonia is a highly toxic substance. Even a slight increase in the concentration of ammonia in the serum leads to impairment of the central nervous system, in extreme cases a comatose state occurs (ammonia intoxication). Therefore a rapid removal of the ammonia formed in the metabolism nitrogen-containing compounds is necessary.

The colourless and odourless, crystallizing, water-soluble end product of the protein metabolism in humans and mammals, formed from 2 molecules NH3 (ammonia) of glutamic acid or from the NH2 group of aspartic acid and 1 molecule carbon dioxide (CO2) with the participation of L-ornithine. The excretion takes place through the kidney (12.6-28.6 g/24 h) after complete filtration into the glomeruli and partial reabsorption into the tubuli; it is reduced in renal insufficiency and liver diseases, increased with increased protein breakdown. The normal values in the serum are 100-450 mg/l (and reach twice the value in sweat). Urea forms inclusion compounds with inorganic and organic acids salts, with organic substances; has a protein denaturing effect in concentrated solution.

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