Influence of contrast media osmolality on intravenous urographic quality.

A clinical study was designed to determine whether the lower solute load after intravenous injection of nonionic contrast medium (CM) produced significant changes in nephrographic and pyelographic quality. For equal iodine doses (300 mg I/kg), the lower solute load of nonionic CM produced better nephrogram and pyelogram scores than ionic CM or nonionic CM with mannitol, both of which had higher solute loads. The higher scores associated with nonionic CM were statistically significant for the pyelogram phase but not for the nephrogram phase. These observations were matched by lesser changes in urinary osmolality and higher urinary iodine concentrations with the nonionic CM.