UREA AND TOTAL NON-PROTEIN NITROGEN IN NORMAL HUMAN BLOOD: RELATION OF THEIR CONCENTRATION TO RATE OF ELIMINATION

Abstract

Folin and his collaborators have recently described extremely accurate and comparatively simple new methods for the determination of the various nitrogenous constituents of the blood and urine.By the use of these methods we may expect a material increase in our knowledge of nitrogen metabolism and excretion in health and disease.For the application of these methods to the study of diseased conditions, however, it is necessary that the normal variation and relationships be first firmly established.It is the purpose of this paper to present the results of experiments on normal adults, having especially in mind the normal urea content of blood and urine.Folin and Denisl report the results of blood analyses made in sixteen normal individuals.In these sixteen cases the total nonprotein nitrogen varied only between 22 and 26 mgm.and the urea nitrogen between 11 and 13 mgm.per 100 grams of blood.They concluded that the "perfectly normal kidney" maintains a constant level of non-protein nitrogen and urea in the blood.All of these sixteen experiments were made in the morning, three to six hours after breakfast.They found, however, that when they made analyses of the blood from any kind of clinical material they found much larger amounts, even though there was no other evidence of kidney disturbance.Others working with the same methods, notably Farr and Austin2 and Agnew,3