Committee on Radiology Water-Soluble Contrast Material

Abstract

Contrast agents available in North America for excretory urography are combinations of sodium and/or meglumine salts of diatrizoate and iothalamate in 50% to 60% solutions (Conray-60, Hypaque Meglumine 60%, Reno-M-60, Renografin-60, and Hypaque Sodium 50%). There is no substantive reason for choosing between these various iodinated contrast agents: packaging, pricing, and quality control are the determinants for their selection. Because of their high osmolarity, the intravenous injection of Renografin-60 (1,400 mOsm/ liter) and Hypaque Sodium 50% (1,170 mOsm/ liter) may result in profound changes in the hemostatic mechanisms of small infants. Blood samples of infants obtained at regular intervals after an injection of 5 ml/kg of Renografin-60 disclosed changes in serum osmolarity, serum sodium levels, and hematocrit values. The mean increase in serum osmolarity three minutes after injection was 15 mOsm/liter, or a 5.3% increase. Hematocrit values decreased by a mean of 7.4%, and the serum sodium concentrations fell by a mean of 4.6 mEq/liter. These values gradually returned to normal in one to four hours.1 Acute expansion of blood volume after the intravenous administration of contrast agents might precipitate heart failure in infants with tenuously compensated congenital heart disease, and the ensuing diuresis may intensify a mild state of dehydration. The magnitude of increase in the intravascular volume may be diminished by slow injections of the contrast material (90 seconds or more) and by injecting a smaller volume (3 ml/kg). Repeat injections should not be administered at less than 30-minute intervals. Occasionally after intravenous contrast materials are injected, Tamm-Horsfall protein will precipitate in the renal tubules, and renal failure may result.