THE VALUE OF THE ESTIMATION OF UREA, NONPROTEIN NITROGEN AND CREATININ

Abstract

Our knowledge of blood chemistry, so far as it concerns renal disease, is of comparatively recent origin. The development of simplified methods of estimating the amount of the various substances in health and disease has rapidly led to the accumulation of enormous data concerning their variations. Estimations of total nitrogen by the Kjeldahl method have been made for a number of years, but this method is too intricate for general clinical use and can be carried out only by trained chemists in well-equipped laboratories. From the determinations made by this method, however, it was well known that in advanced renal disease the total nitrogen in the blood was greatly increased, and later observations have shown that this increase is due in great measure to the retention of nitrogenous end-products, normally excreted by the healthy kidney. As urea is the most prominent of these substances, blood urea determinations were at first,