Estimation of Renal Function based on Specific Gravity Changes Following Intravenous Urography

Abstract

Baumrucker investigated the changes in sp. gr. of urine following intravenous urography as a test of renal function. After the inj. of diodrast the urine shows a rise in its sp. gr. in proportion to the concentration of the dye in the excreted urine. There is a close parallel between the visualization of the pyelogram and the amount of rise in sp. gr. following inj. of diodrast. This increase in sp. gr. allows computation of the amt. of dye excreted and the dye % excreted. An equation is offered as a quick means of calculating kidney function. Therefore, while excretion pyelograms indicate the concentrating ability of the kidney, the equation supplies the numerical equivalent, or the % excreted. Kidneys unable to concentrate urine following inj. of diodrast enough to cause an added rise in the sp. gr. of the excreted urine of .018 (as from 1.024 to 1.042) will usually have fainter pyelograms. The significance of these findings is discussed.