Nephropathy induced by contrast medium may be less likely to develop in high-risk patients when iodixanol is used rather than a low-osmolar, nonionic contrast medium.

Increased urinary albumin excretion, microalbuminuria, may be the first sign of early diabetic nephropathy. We examined glomeruli by morphometric methods in 17 patients with Type 1 (insulin-dependent) diabetes mellitus and microalbuminuria. The median age was 19 (range 18-29) years, duration of diabetes 12 (8-15) years, mean blood pressure 93 (87-115) mm Hg, glomerular filtration rate 132 (101-209) ml.min-1.1.73 m2 -2, albumin excretion rate (mean over 1 year) 32 (15-194) micrograms/min. Reference data were obtained from 11 healthy kidney donors. Mesangial volume estimates were obtained by serial sectioning in three total profiles in each of three glomeruli in diabetic patients. Basement membrane thickness and matrix volume fraction were estimated from one level per glomerulus. Two matrix parameters, matrix star volume and matrix thickness, were estimated. Interstitial volume fraction in cortex was measured by light microscopy. The morphological parameters were significantly increased in the diabetic group compared to the control group, basement membrane thickness (mean with 95% confidence intervals) was 595 nm (549-641 nm) vs 305 nm (287-325 nm), p = 0.0001; mesangial volume fraction 0.22 (0.21-0.23) vs 0.19 (0.18-0.21), p = 0.04, and matrix volume fraction 0.13 (0.12-0.13 vs 0.09 (0.08-0.10), p = 0.001. Also matrix star volume and thickness, interstitial volume fraction and mean capillary diameter were significantly increased. The intra-individual variation among glomeruli expressed as coefficient of variation was 7.4% vs 9% (basement membrane thickness) and 11.7% vs 25% (mesangial volume fraction) in the diabetic and the control group, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The numbers of contrast media (CM)-enhanced examinations are increasing. The annual sale of iodine for CM now represents 60 million CM doses a year world-wide. In spite of improvements in chemical structure, CM are still the third leading cause of hospital-acquired acute renal failure. The definition of contrast nephropathy (CN) is discussed, as well as the mechanisms involved in the pathogenesis. Low osmolar contrast media (LOCM) are less nephrotoxic than high osomolar contrast media (HOCM) and cause fewer osmotoxic side-effects such as pain and heat sensations. The non-ionic dimeric contrast media which are iso-osmolar to plasma (IOCM) cause even fewer haemodynamic side-effects and result in better opacification of the urinary tract than LOCM. The nephrotoxicity of IOCM is low. The risk factors for CN and methods for prevention of CN are discussed.

The dialyzability of iohexol was examined in patients with chronic renal failure on long-term hemodialysis treatment. Eight patients had iohexol (Omnipaque® 240 or 350 mg I/ml) injected in doses between 98 and 1,493 mg I/kg body weight (BW) 25 h (mean time) before start of hemodialysis. Dialysance of iohexol was 81 ± 15 ml/min (mean ± SD) compared to 120 ± 16.8 ml/min for creatinine. Elimination half-life for iohexol during hemodialysis was 3.9 ± 1.1 h while plasma clearance was 64 ± 17 ml/min. The distribution volume calculated (0.25 ± 0.05 liters/kg BW) confirms previous observations with distribution in the extracellular fluid only. Before the start of hemodialysis 36 ± 28% of the dose injected was eliminated, indicating some extrarenal elimination. After 4 h of hemodialysis 72 ± 11% of the dose was removed.

A new nonionic dimeric contrast medium (CM), iodixanol, was intravenously administered to 40 healthy male volunteers in doses of 0.3-1.2 g of iodine per kilogram of body weight, nonionic monomeric iopamidol and iopentol were administered to 20 others, and the renal effects were studied up to 120 hours after administration. Computed tomography of the kidneys was performed up to 80 hours after injection. Creatinine clearance as an index of the glomerular filtration rate was unchanged with all CM. Urine volume and osmolar clearance increased most with the monomeric CM. The proximal tubular brush border enzyme alkaline phosphatase increased with all CM. The lysosomal enzyme N-acetyl-beta-glucosaminidase increased more with the monomeric CM than with iodixanol. A persistent increased attenuation in the region of the cortex was observed with all CM. Attenuation returned to baseline within 80 hours, with the slowest decline with iodixanol. This delayed cortical enhancement did not correlate with the effects of the CM on the tubular enzyme excretion.