[Study on free enzymes and proteins in the urine. Report IV: The effects of Iohexol on elderly patients with renal function disorder].

We assessed the nephrotoxicity of a non-ionic contrast medium, Iohexol, in 18 elderly patients. They were divided into two groups. Group 1 consisted of 12 patients with glomerular flow rate (GFR) above 60 ml/min/1.73 m2 (range 69-136; average 96) and group 2 consisted of 6 patients with GFR below 60 ml/min/1.73 m2 (range 38-59; average 49). Urine samples, collected before, immediately after, and on the third and sixth days after drip infused pyeloureterography (DIP) were analyzed for gamma-glutamyl transpeptidase (gamma-GTP), N-acetyl-beta-D-glucosaminidase (NAG), beta 2-microglobulin (beta 2-MG) and albumin. In group 1, immediately after DIP, the urinary excretion of albumin, gamma-GTP and NAG were significantly increased (p < 0.01, p < 0.01, p < 0.01). In group 2, immediately after DIP, the urinary excretion of gamma-GTP and beta 2-MG were significantly increased (p < 0.01, p < 0.1). The gamma-GTP and NAG values in both groups suggest that the damage of proximal tubules cells will not continue for more than 4 days. However, as for the reabsorption of beta 2-MG on proximal tubules, in group 2 the value did not return to the pre DIP level until 6 days after DIP. We believe it is important to postpone injection of non-ionic contrast medium within 6 days of its last usage.