Radiology, Vol 148, 55-59, Copyright © 1983 by Radiological Society of North America
Work in progress: reduction of calcium activity by radiopaque contrast media
TW Morris, LG Sahler, M Violante and HW Fischer
An in vitro examination of the effects of radiopaque contrast media anions,
cations, additives, and ionic strength on ionic calcium level using
ion-specific electrodes was made. The calcium-binding additives sodium
citrate and sodium EDTA produced the largest reduction in ionic calcium. At
the same iodine concentration the anions diatrizoate, iothalamate,
metrizoate, and ioxaglate reduced ionic calcium by essentially the same
amount. Sodium compounds reduced ionic calcium more than did meglumine
compounds, a difference that is probably related to dissociation. The
nonionic compounds iohexol and iopamidol did not reduce ionic calcium
significantly. Ionic strength appears to have little direct effect on ionic
calcium at and above physiologic levels. All ionic contrast media bind
significant amounts of ionic calcium at the high concentrations achieved
during selective arteriography. Since the anions are only weak calcium
binders supplemental calcium can restore the level of ionic calcium.
