Determination of Glomerular Filtration Rate with Contrast Media

Gadolinium contrast media are more nephrotoxic than a low osmolar iodine medium employing doses with equal x-ray attenuation in renal arteriography: An experimental study in pigs1

“…In spite of that, we think it is possible to make a reasonable comparison between the three CM with regard to their effect on total body clearance (representing GFR) according to the formula. Gadopentetate, gadodiamide, and iohexol all have high water-solubility, low binding to plasma proteins, main distribution in extracellular spaces, very small intracellular distribution, and a body clearance dominated by glomerular filtration (22)(23)(24)(25)(26). In man and several animal species, the plasma half-lives are shorter and the Vd tends to be smaller for the two Gd-CM than for I-CM (22)(23)(24)(25)(26).…”

“…Gadopentetate, gadodiamide, and iohexol all have high water-solubility, low binding to plasma proteins, main distribution in extracellular spaces, very small intracellular distribution, and a body clearance dominated by glomerular filtration (22)(23)(24)(25)(26). In man and several animal species, the plasma half-lives are shorter and the Vd tends to be smaller for the two Gd-CM than for I-CM (22)(23)(24)(25)(26). If the plasma half-lives in the present study should mean the same body clearance for the Gd-CM and the I-CM according to the formula, then the Vd in pigs for gadopentetate should be 23 times that of iohexol (3,340/143) and for gadodiamide 80% higher (256/143) than the Vd of iohexol.…”

“…Their body clearance from plasma is dominated by glomerular filtration with no significant tubular excretion or reabsorption (22)(23)(24)(25)(26). Hence, both types of CM function as markers of GFR and may as such be used to evaluate their own nephrotoxic effects (ie, their possible depression of GFR).…”

“…The larger a CM-induced depression of GFR is, the lower the body clearance of the GFR marker (the contrast medium) from plasma will be, with subsequent prolongation of its plasma half-life elimination time. The plasma half-life of the contrast media was calculated by using a one-compartment model and linear regression analysis of logarithmic plasma concentrations (22) in the period 1-3 hours after injection.…”

Gadolinium contrast media are more nephrotoxic than iodine media. The importance of osmolality in direct renal artery injections

“…This is based on the knowledge that both types of CM have glomerular filtration as dominating mechanism of body clearance and similar volume of distribution (Vd) in the extracellular space [22,23]. Thus, according to the equation: plasma half-life (T1/2) = ln2*Vd/body clearance [24], where ln2 is the natural logarithm (ln2=0.693), possible differences in plasma half-life following injections of Gd-and I-CM into the renal arteries will mainly be dependent on different effects on GFR.…”