Split Renal Function Studies in Hypertension

Following the observation of split renal function studies by White in 1950,1later modified as a diagnostic test for renovascular hypertension by Howard et al in 1954,2it seemed possible that split renal function studies might be relied upon to provide a basis for the identification of patients with hypertension resulting from a diminished blood flow to one kidney. In 1957, Conner and associates3reported that in cases of unilateral renovascular disease the blood pressure improved after surgery only when the preoperative test had shown a diminished urine flow and sodium concentration on the involved side. A number of methods have subsequently been used to improve the performance or interpretation of split renal function tests, namely those of Rapoport in 1960,4Stamey in 1961,5and Birchall et al in 1962.6It is apparent from the number of tests which have been introduced as well as from published reports,7-10that no