The average composition of normal human urine in grams per 100 cm3 approximately consists of 96g of water, 1.8g of mineral salts (sodium chloride), 2.0g of urea and 0.2g of other nitrogenous substances.
However, the composition of normal urine varies considerably depending on several factors. For instance, taking a protein rich diet will result in more urea being present in the urine. This is because proteins are deaminated in the liver with subsequent urea formation. Even sugar can appear in a normal person after a heavy intake. If other conditions are constant, a larger intake of liquids or water rich food increases the volume of water in blood, hence more urine is excreted. This also happens in cold weather when sweat secretion is reduced. Similarly if you take in salty foods the excess salts will be excreted in the urine. Abnormal constituents of urine found in certain diseases. For example, in sugar diabetes the urine contains a considerable amount of glucose. This is because the body is unable to store up excess glucose in the form of glycogen This may be due to the inability of the pancreas to secrete insulin. Insulin is the hormone needed by the liver to change glucose to glycogen.
