A Simple Method for Determining Effective Renal Blood Flow and Tubular Excretory Mass in Man. ∗

Abstract

Quantitative methods for the determination of the tubular excretory mass and the rate of blood flow through the active renal tissue by diodrast clearance have been developed by Smith and his associates 1 and have been used in recent years almost entirely for the purpose of research. We have suggested recently^2-4 that the determination of the effective renal blood flow in patients with arterial hypertension might furnish not only interesting data on the pathogenesis of the disease, but also information of considerable value for the prognosis and selection of patients to be submitted to surgical treatment.

To confirm this possibility it became necessary to find a simple method suitable for the routine clinical study of a large number of patients. The methods of Smith and his associates are not practical as they require continuous intravenous infusion, inlying catheter, the full attention of a physician and a technician for several hours, and a large number of chemical determinations.

To our knowledge, Findley and White 5 made the only attempt to simplify the determination of effective renal blood flow, by the use of a single subcutaneous injection of diodrast. They measured effective renal blood flow in 3 hypertensive subjects by 3 consecutive clearance periods. The determinations were not repeated on different days, or control!ed by the determination of the ratio of effective renal blood flow to tubular excretory mass. Normal individuals have not been studied. Since the blood flow in hypertensive patients varies widely from case to case, there is no definite standard to which the low values obtained by Findley and White can be compared. Furthermore, the results may have been influenced by the local anesthetic which they used at the site of injection.