Urine viscosity after injections of iotrolan or iomeprol

PURPOSE: Previous observations in rats caused us to speculate whether the injection of iotrolan, a nonionic dimeric contrast medium (CM), would increase urine viscosity enough to obstruct urine outflow in the collecting duct. MATERIAL AND METHODS: The urine viscosity in dogs was measured directly with a viscosimeter after injections of iotrolan or of iomeprol, a nonionic monomeric CM. RESULTS AND CONCLUSION: The injection of iotrolan increased urine viscosity considerably whereas iomeprol had little effect on this variable. The osmolality-dependent adverse reactions of CM have previously been emphasized but viscosity-dependent adverse reactions must also be considered when the CM is a polymer with a low osmolality.