Contrast media-induced renal tubular vacuolization. A light and electron microscopic study on rat kidneys.

The morphologic changes in healthy rat kidneys (n = 102) were studied 2 or 48 hours after intravenous injection of 1 or 3 g iodine (I)/kg of high-osmolality diatrizoate, low-osmolality iopromide and iohexol, or iso-osmolality iotrolan, as well as after 0.2 or 0.6 g/kg of the high-osmolality magnetic resonance contrast medium gadolinium DTPA. Physiologic saline was injected in controls. The kidneys were fixed by perfusion and the specimens were analyzed semiquantitatively by two independent observers blinded to the treatment. A statistically significant (P less than .01) cytoplasmic vacuolization was noticed in the proximal convoluted tubule cells 2 hours after injection of 3 g I/kg of diatrizoate or iopromide. Iohexol and iotrolan induced an even more significant (P less than .01) and longer-lasting vacuolization, but gadolinium DTPA did not produce lysosomal alterations. Although the vital cell organelles remained intact, reversible lysosomal alterations may represent the first structural signs of a threatening cellular injury.