Urea Clearance in Normal and in Dehydrated Infants

Abstract

A large number of investigators have measured the end-products of nitrogen metabolism in the blood and their excretion in the urine in health and in disease as an aid in evaluating the functional capacity of the kidneys. Ambard and Weill 1 were the first to relate the concentration of urea in the blood to its concentration in the urine and to the urinary volume as expressed by "Ambard's coefficient." Addis and his collaborators 2 showed that more constant results could be obtained if, under standard conditions of fluid intake, the rate of urea excretion was measured as ureain 1 hour's u r i n e u r e a i n 100 cc. of b l o o d . They introduced the assumption, and supported it by animal experiments, that the weight of the kidney is proportional to surface area rather than body weight, which was used by Ambard. Under Addis' standard conditions the volume of urine in normal persons was above 2 cc. per minute.Van Slyke and his co-workers3 supplied an explanation for the constancy of Addis' ratio. They observed that above a certain urinary This investigation was assisted by the Josiah Macy, Jr., Foundation. From the