Renografin-60 for urography: effect on serum electrolytes and proteins in adults

A prospective study was done on 27 adults to assess the changes in serum electrolytes and proteins induced by bolus administration of 100 ml of the ionic contrast medium diatrizoate meglumine and sodium (Renografin-60) for IV urography. Statistically significant changes in serum sodium, chloride, potassium, calcium, bicarbonate, phosphate, total proteins, and albumin were shown at 5 min postinjection. The mean percentage decreases were sodium 2%, chloride 2%, potassium 9%, calcium 13%, bicarbonate 9%, phosphate 10%, and proteins 15%. A mean 3% increase in serum osmolality was observed. By 30 min, sodium and chloride levels had returned to baseline; potassium, calcium, and albumin values were incompletely recovered; bicarbonate was not significantly changed from 5 min; and phosphate values continued to decrease. An in vitro dialysis experiment in which different volumes of Renografin-60 were dialysed against an electrolyte solution (pseudoserum) produced a dilutional factor of 5 to render a given volume of the contrast isoosmotic with plasma. The observed changes from the baseline values of the electrolytes and proteins up to 10% are therefore assumed to be due to hemodilution resulting from movement of fluid from the extravascular to the intravascular compartment. This study confirms alterations in serum levels of several electrolytes after the use of ionic contrast media beyond simple hemodilution. Although these changes appear not to be clinically significant in this investigation, the alterations in potassium and calcium may contribute to arrhythmias, particularly when hypokalemia or hypocalcemia preexists.