Search

Purpose: To derive new formulae for the calculation of single sample clearance of the contrast medium iohexol and to compare the formulae to a selection of existing single sample clearance formulae derived for the calculation of 51Cr-EDTA and 99mTc-DTPA clearance., Material and Methods: Glomerular filtration rate (GFR) was calculated from total plasma clearance of iohexol used for urography in 902 patients. Two plasma samples were drawn in each patient. Automated x-ray fluorescence analysis equipment was used for the plasma iodine analysis. Single and multiple sample iohexol clearance values were compared. In 77 patients the multiple sample clearance values were additionally compared to a 51Cr-EDTA clearance performed simultaneously or within 14 days., Results: The precision of the results calculated by the existing single sample clearance formulae and the derived iohexol single sample clearance formulae were essentially the same. The most precise of the derived formulae was that based on the Bak Christensen & Groth formula. The correlation between multiple sample clearance of iohexol and 51Cr-EDTA was high (r = 0.918)., Conclusion: Iohexol can substitute 51Cr-EDTA for GFR measurement. A valid GFR can be calculated from a single plasma sample determination of iohexol clearance using either the existing formulae or the new formulae derived from the present study.

A randomized study was conducted in 43 patients who were in pain due to acute ureteral obstruction. Emergency urography was performed in all patients, using either a low osmolar non-ionic (iohexol) or a high osmolar ionic (metrizoate) contrast medium. Increase of pain following injection of contrast media was found in 56 percent of all patients. Increase of pain occurred with both contrast media without any difference between the degree of pain nor the number of patients who experienced an increase of pain. Delayed excretion was considered the only reliable indicator of the degree of obstruction in the present study. Nineteen (68%) of the 28 patients with a delayed excretion greater than 10 min experienced increased pain while the incidence of pain increase was significantly lower (33%) in patients without that sign of ureteral obstruction (p less than 0.05). The increase of pain was not associated with a simultaneous increase of the mean arterial blood pressure.