ABSTRACT
A test for the presence or absence of protein in the urine is one of the most frequently performed procedures in routine urinalysis. For more than a century, clinical tests were based on precipitation phenomena involving the coagulation of protein by heat and by various chemical agents, including concentrated nitric acid, trichloroacetic acid, and sulfosalicylic acid. Proteins are large, complex molecules which are polymers of 20 to 25 separate amino acids. The proteins display a great diversity of chemical, physical, and physiological properties, but they are quite closely related chemically. The initial tests for protein in urine involved precipitation procedures. Tests for protein in urine are ordinarily nonspecific, and in general they do not differentiate as to which type of protein is present. Current colorimetric tests for protein in urine possess the advantages that they are convenient, easy to use, and require no equipment.
