Renal effects of nonionic contrast media after cardioangiography

A prospective double-blind randomized cardioangiographic study with iopentol and iohexol was performed in 60 patients. Glomerular filtration rate (GFR) was assessed by serum values of creatinine and beta 2-microglobulin (beta 2-MG), estimated creatinine clearance (CCr) according to Cockroft & Gault's formula, and 24 hour CCr. The urinary excretion of albumin, beta 2-MG, and of the renal tubular enzymes alkaline phosphatase (ALP) and N-acetyl-beta-glucosaminidase (NAG) was also measured. Contrary to what has been found after i.v. injections, GFR was reduced by both nonionic contrast media. Serum creatinine (S-Cr) was increased by more than 25% in 6 patients, 3 in each group. CCr was more sensitive than S-Cr and S-beta 2-MG, but this method is less precise because of risk of urine sampling errors. Estimated CCr gave no additional information to S-Cr. The urinary excretion of NAG and ALP was increased. No clinically significant differences between iopentol and iohexol were detected. No correlation was found between the changes in tubular function parameters and changes in GFR. Twenty patients were on calcium channel blockers before the investigation, but this had no protective effect on the renal function parameters.