Diodrast and Inulin Clearances in Nephrotic Children with Supernormal Urea Clearances.

Elevation of the urea clearance above the calculated normal value has been frequently observed in our clinic in children with the nephrotic syndrome. Previous studies of this phenomenon have shown it to be related to the intake of protein, but not induced by the oral administration of urea (1). Glomerular filtration, measured by inulin clearance, has been found by Emerson, Futcher, and Farr (2) to be elevated as much or more than the urea clearance. The present study is an attempt to answer the question raised in the last report (2) as to whether renal blood flow is elevated proportionately to the glomerular filtration rate. Evidence presented by Goldring, Chasis, Ranges, and Smith (3) and by White and Heinbecker (4) indicates that the diodrast clearance approximates the renal blood flow in man. In order to obtain some indication as to whether the high urea and inulin clearances observed in nephrosis are probably due to filtration of an increased fraction of plasma water or to an increased renal blood flow, we have therefore, in 4 cases, made a series of simultaneous determinations of the clearances of urea, inulin, and diodrast.