The effect of contrast media on immature renal function. Comparison of agents with high and low osmolality.

Contrast media having high osmolality (methylglucamine diatrizoate; 1,510 mOsm/kg) and low osmolality (triiodoisophthaldiamide, 616 mOsm/kg) were compared in 15 functionally immature rabbits 2-3 weeks of age. Renal function was assessed with a gamma camera and whole-body counter, using excretion of technetium-99m-tin-DTPA as an index of glomerular filtration rate. Both DTPA and the contrast agent (2 ml/kg) were injected as a single intravenous bolus in 15 seconds. After 40 minutes, per cent DTPA excreted was 33.0 +/- 2.3 for triiodoisophthaldiamide and 28.2 +/- 1.5 (p less than 0.01) for methylglucamine diatrizoate. Excretion of DTPA was reduced with the latter (p less than 0.005) but not the former agent (p greater than 0.6). Thus contrast materials with high osmolality depress renal function in immature rabbits, suggesting that agents with low osmolality are preferable for use in newborns.