Comparison of several methods for semiquantitative determination of urinary protein.

Two types of urine protein dipsticks and the sulfosalicylic acid method were compared for their accuracy and specificity, with use of urine samples supplemented with various proteins. Dipsticks yield accurate results when the protein under consideration is restricted to albumin; the sulfosalicylic acid method accurately determines many kinds of proteins in addition to albumin. Detergents affect each of the methods, but changes in salt concentration only affect results by dipstick procedures. Dipsticks, which are based on the protein-error principle for indicators, are subject to some of the conditions that apply to the bromcresol green method for serum albumin determination.