Short communication: renal function and the excretion of contrast agents

The renal excretion of intravascular iodinated X-ray and gadolinium chelate MR contrast is examined theoretically. An expression is derived for the proportion of an administered dose of such an agent excreted in any given time in the face of varying levels of renal function. It is shown that a family of curves may be generated from which an estimate of this proportion for any time may be made. Some circumstances in which such knowledge may be useful are briefly discussed.