Glomerular filtration rate estimated after multiple injections of contrast medium during angiography

In twenty-six patients referred for angiography, clearance of contrast medium was determined with x-ray fluorescence analysis after multiple injections of contrast medium. A formula for correction of the injected amount, which takes into consideration the different times of contrast medium injections, approximating the total injected amount into one injection, was used. A single injection clearance of 51Cr-EDTA was determined at the same time. The results showed a good correlation between the clearance of contrast medium after multiple injections and the 51Cr-EDTA clearance after a single injection (r = 0.945). The correlation between contrast medium clearance calculated without correction for the different injection times, and 51Cr-EDTA clearance was the same (r = 0.946), due to short angiography time and rather low clearance values in our patients. It is concluded that total plasma clearance of contrast medium can easily be estimated after multiple injections. In this way patients with a risk of developing post-angiographic renal failure can be found.