ABSTRACT
Normal urine is a fluid of widely varying composition. Literally thousands of compounds have been identified in normal urine, and the vast majority of these have been derived from the blood. The understanding of the composition of the urine has gradually evolved as the sciences of chemistry and physiology have developed. Urea is the principal waste product of protein metabolism. It is formed in the liver, and its concentration in the urine varies somewhat with the amount of protein, particularly meat, in the diet. Urine can be regarded as one of the most complex of all body fluids. It contains practically all of the constituents found in the blood. One of the primary limitations of urine study is the fact that the time interval over which the urine is formed cannot be clearly defined. The general factors which provide for obtaining good results are related to proper collection and care of the specimen.
