[Methods of qualitative detection of proteinuria in mass surveys].

Abstract

In a survey of the qualitative methods of research into proteinuria, the Authors recall, apart from later modifications, the old techniques based on the occurrence of turbidity from precipitation of proteins obtained with heat and/or by the use of various anionic reagents. Particular attention is given to the rapid tests with paper strip based on the phenomenon of error made by indicators in the presence of protein solutions. Their sensitivity, their specificity and above all the fact that their use is unbeatably practical are discussed, both on the basis of data derived from other studies and on the basis of various personal observations. From the latter, the Authors deduce and demonstrate the substantial constancy in the behaviour of various types of paper strip test, even those produced in different periods and by different manufacturers; how the data obtained with these various papers can be compared with the best modern methods of measuring turbidity; and the different sensitivities of the papers with various types of proteins such as albumins, globulins and in particular immunoglobulinic micromolecular fragments. Finally, they show that falsely positive reactions in alkaline urines because of ammoniacal fermentation cannot be ascribed to the increase of pH, but rather directly to an excess of ammonium ions. After having remarked that tests with paper strip have to a large extent taken the place of classical methods, more for obvious reasons of expediency than for any real qualitative superiority, the Authors maintain that it is advisable, though only in border-line cases, to make a routine check with one of the traditional methods in order to screen genuine cases of proteinuria.