The Relation Between the Serum Urea Concentration and the Protein Consumption of Normal Individuals 1

When a patient with renal disease is found to have a concentration of urea in his blood that is higher than usual we would like to be able to derive from the degree of increase in concentration some idea as to the degree of decrease in the urea-ex-creting function of his kidneys. In the individual patient this cannot safely be done. True, when we plot the blood urea concentrations of a large number of patients against their urea clearances, a general relation does emerge (1, 2). However, in any one of such a group of patients the predic-tion from concentration to clearance may fall dangerously far from the truth. This is inevitable because the concentration of urea in the body is determined not only by how much urea runs out