Renal toxicity of contrast agents: iopamidol, iothalamate, and diatrizoate

Unexpected degradation and deiodination of diatrizoate by the Cu(II)/S(IV) system under anaerobic conditions

Transition metal catalyzed sulfite auto-oxidation is a promising technology used in water and wastewater treatment for the elimination of contaminants. In the literature, this process has been reported to be efficient only in the presence of oxygen. However, in this study, we unexpectedly found that the degradation of diatrizoate (DTZ) by a system based on the combination of copper ion and sulfite (Cu(II)/S(IV)) reached over 95% under anaerobic conditions, but was considerably retarded under aerobic conditions at pH 7. Furthermore, it was found that Cu(I), generated from the cleavage of the CuSO₃ complex, was the main reactive species responsible for the degradation of DTZ by the Cu(II)/S(IV) system under anaerobic conditions. In fact, the absence of oxygen promoted the accumulation of Cu(I). The concomitant release of the iodide ion with the degradation of DTZ indicated that the anaerobic degradation of DTZ by the Cu(II)/S(IV) system mainly proceeded through the deiodination pathway, which was also confirmed by the detection of deiodinated products. The anaerobic degradation of DTZ was favored at higher initial concentrations of Cu(II) or sulfite in this system. Since the CuSO₃ complex, the precursor of Cu(I), was formed mainly at pH 7, the highest anaerobic degradation of DTZ was achieved at pH 7. An increase in reaction temperature considerably enhanced the degradation of DTZ by the Cu(II)/S(IV) system with an apparent activation energy of 119.4 kJ/mol. The presence of chloride, bicarbonate and humic acid slightly influenced the anaerobic degradation of DTZ. The experiments with real water samples also demonstrated the effectiveness of the degradation of DTZ by the Cu(II)/S(IV) system under anaerobic conditions.

Highly efficient degradation of iohexol on a heterostructured graphene-analogue boron nitride coupled Bi2MoO6 photocatalyst under simulated sunlight

Iohexol (IOH), as a typical iodinated X-ray contrast media (ICMs) with potential threat to human health, is difficult to be removed with the conventional wastewater treatment methods. In this work, new boron nitride coupled Bi₂MoO₆ layered microspheres (BN/Bi₂MoO₆) composites were applied to remove IOH from water via photocatalytic degradation. The degradation constant k_app of IOH over 3.5 wt% BN/Bi₂MoO₆ was 0.016 min^-1, which was 3.2 times that of Bi₂MoO₆ (0.005 min^-1). The degradation rate of IOH on 3.5 wt% BN/Bi₂MoO₆ reached 92% in 150 min. The enhanced photocatalytic activity of BN/Bi₂MoO₆ can be attributed to the heterojunction between BN and Bi₂MoO₆. The matched type-I band alignment heterojunction of two semiconductors prominently improved the charge separation. Based on the trapping experiments, holes and superoxide radicals were proved to be the main active species for photocatalytic IOH degradation. Besides, the degradation products of IOH were analyzed by LC-HRMS and the possible degradation mechanism of IOH was also proposed in this work.

Evaluation of X-ray tomography contrast agents: A review of production, protocols, and biological applications

X-ray computed tomography is a strong tool that finds many applications both in medical applications and in the investigation of biological and nonbiological samples. In the clinics, X-ray tomography is widely used for diagnostic purposes whose three-dimensional imaging in high resolution helps physicians to obtain detailed image of investigated regions. Researchers in biological sciences and engineering use X-ray tomography because it is a nondestructive method to assess the structure of their samples. In both medical and biological applications, visualization of soft tissues and structures requires special treatment, in which special contrast agents are used. In this detailed report, molecule-based and nanoparticle-based contrast agents used in biological applications to enhance the image quality were compiled and reported. Special contrast agent applications and protocols to enhance the contrast for the biological applications and works to develop nanoparticle contrast agents to enhance the contrast for targeted drug delivery and general imaging applications were also assessed and listed.

Catalytic Degradation of Diatrizoate by Persulfate Activation with Peanut Shell Biochar-Supported Nano Zero-Valent Iron in Aqueous Solution

An emerging pollutant, diatrizoate (DTZ) has been frequently detected in aqueous solution. Unique reticular peanut shell biochar (BC)-supported nano zero-valent iron (nZVI) composite (nZVI/BC) was successfully synthesized and used as a catalyst for activating persulfate (PS) to promote the removal of DTZ. The structure and morphology of the nanocomposite materials were characterized by scanning electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller measurements, and Fourier transform infrared spectroscopy. The degradation of DTZ (20 mg L^-1) was achieved by activating PS with the nanocomposite material. The removal of DTZ reached nearly 100% using 25 mM PS and 0.45 g L^-1 nZVI/2BC (mass ratio of nZVI and BC at 1:2) nanocomposite material at pH 3.0 and 25 °C. Influencing factors, such as dosages of nZVI/2BC and PS, temperature, and pH were also investigated. The mechanisms of PS activation with nZVI/2BC were discussed, including BC property, electron transfer, and the identification of free radicals in the reaction. The findings demonstrated that nZVI/BC-PS (peanut shell BC-supported nZVI activating PS) is a promising material for the treatment of refractory organic pollutants.

A novel method for photo-oxidative degradation of diatrizoate in water via electromagnetic induction electrodeless lamp

In this study, an electromagnetic induction electrodeless lamp (EIEL) was first introduced into UV advanced oxidation processes (AOPs) for photodegradation of Diatrizoate (DTZ), which was the most persistent iodinated X-ray contrast medium (ICM), and traditional Hg lamps were taken as references. Direct photolysis rate of DTZ under EIEL irradiation was 1.34 times as that under Hg irradiation, but the electric energy consumption was 0.87 times. In this sense, the combination of EIEL and oxidants (O₂, H₂O₂ and S₂O₈^2-(PS)) was further investigated. The remarkably increased photodegradation rates were observed in UV/PS system due to primary contribution rate of SO₄^- (62.5%) based on the results of radical concentrations and second-order rate constants of DTZ with SO₄^- and OH. Inorganic ions influencing the photodegradation process were investigated. The effect of natural organic materials (NOMs) in UV/PS system was studied based on contribution ratios of light screening effect and quenching. Transformation mechanisms of DTZ in UV/PS system included deiodination, intramolecular cyclization, decarboxylation, deacetylation and deamination, which were further confirmed by frontier electron density calculations. The study indicated that UV/PS with EIEL irradiation has the potential to remove pharmaceuticals in contaminated aquatic environments.

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 β2-microglobulin (β2-MG), estimated creatinine clearance (CCr) according to Cockroft & Gault's formula, and 24 hour CCr. The urinary excretion of albumin, β2-MG, and of the renal tubular enzymes alkaline phosphatase (ALP) and N-acetyl-β-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-β2-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.

Renal Effects of the Non-Ionic Contrast Medium Iopentol after Intravenous Injection in Healthy Volunteers

Renal effects of the new non-ionic contrast medium iopentol in increasing doses were assessed and compared with the effects of physiologic saline. Twenty-four healthy male volunteers, allocated to three dose groups, were given iopentol intravenously in doses of 0.3, 0.6, and 1.2 g I/kg body weight, respectively. The highest dose group was also given physiologic saline separately as a control. The diuresis increased in all groups, most in the highest dose group, and with a concomitant fall of urine osmolality and increase in osmolar clearance. A slight decrease of serum osmolality, creatinine and urea occurred at 3 hours due to hemodilution. The glomerular filtration rate was unaffected by iopentol. The urinary excretion of albumin and β2-microglobulin was unchanged. However, urinary N-acetyl-β-glucosaminidase and alkaline phosphatase increased significantly, most in the highest dose group. All changes were reversible.

Renal Effects of Iopentol and Iohexol after Intravenous Injection

Renal effects of the 2 non-ionic contrast media iopentol and iohexol were investigated and compared in a double-blind, randomized parallel study where 30 patients received iopentol, and 31 patients iohexol intravenously for abdominal CT. The dosage of contrast medium (350 mg I/ml) was 700 mg I/kg body weight. Only one patient (in the iohexol group) had an increase in serum creatinine of more than 50%. Iopentol and iohexol had no effects on the mean serum values of creatinine, urea, and β2-microglobulin (β2-MG) nor on creatinine clearance. The urinary excretion of albumin and β2-MG was also unchanged. The excretion of the proximal tubular enzymes alkaline phosphatase and N-acetyl-β-glucosaminidase was increased. No significant difference between iopentol and iohexol was found.

Removal of the X-ray contrast media diatrizoate by electrochemical reduction and oxidation

Due to their resistance to biological wastewater treatment, iodinated X-ray contrast media (ICM) have been detected in municipal wastewater effluents at relatively high concentrations (i.e., up to 100 μg L(-1)), with hospitals serving as their main source. To provide a new approach for reducing the concentrations of ICMs in wastewater, electrochemical reduction at three-dimensional graphite felt and graphite felt doped with palladium nanoparticles was examined as a means for deiodination of the common ICM diatrizoate. The presence of palladium nanoparticles significantly enhanced the removal of diatrizoate and enabled its complete deiodination to 3,5-diacetamidobenzoic acid. When the system was employed in the treatment of hospital wastewater, diatrizoate was reduced, but the extent of electrochemical reduction decreased as a result of competing reactions with solutes in the matrix. Following electrochemical reduction of diatrizoate to 3,5-diacetamidobenzoic acid, electrochemical oxidation with boron-doped diamond (BDD) anodes was employed. 3,5-Diacetamidobenzoic acid disappeared from solution at a rate that was similar to that of diatrizoate, but it was more readily mineralized than the parent compound. When electrochemical reduction and oxidation were coupled in a three-compartment reactor operated in a continuous mode, complete deiodination of diatrizoate was achieved at an applied cathode potential of -1.7 V vs SHE, with the released iodide ions electrodialyzed in a central compartment with 80% efficiency. The resulting BDD anode potential (i.e., +3.4-3.5 V vs SHE) enabled efficient oxidation of the products of the reductive step. The presence of other anions (e.g., chloride) was likely responsible for a decrease in I(-) separation efficiency when hospital wastewater was treated. Reductive deiodination combined with oxidative degradation provides benefits over oxidative treatment methods because it does not produce stable iodinated intermediates. Nevertheless, the process must be further optimized for the conditions encountered in hospital wastewater to improve the separation efficiency of halide ions prior to the electrooxidation step.

Preclinical molecular imaging using PET and MRI

Molecular imaging fundamentally changes the way we look at cancer. Imaging paradigms are now shifting away from classical morphological measures towards the assessment of functional, metabolic, cellular, and molecular information in vivo. Interdisciplinary driven developments of imaging methodology and probe molecules utilizing animal models of human cancers have enhanced our ability to non-invasively characterize neoplastic tissue and follow anti-cancer treatments. Preclinical molecular imaging offers a whole palette of excellent methodology to choose from. We will focus on positron emission tomography (PET) and magnetic resonance imaging (MRI) techniques, since they provide excellent and complementary molecular imaging capabilities and bear high potential for clinical translation. Prerequisites and consequences of using animal models as surrogates of human cancers in preclinical molecular imaging are outlined. We present physical principles, values and limitations of PET and MRI as molecular imaging modalities and comment on their high potential to non-invasively assess information on hypoxia, angiogenesis, apoptosis, gene expression, metabolism, and cell trafficking in preclinical cancer research.

Renal effects of cardiac angiography with different low-osmolar contrast media

The aim of this study was to evaluate the renal effects of cardiac angiography performed with three low-osmolar contrast media (CM): iopromide (IPR), ioversol (IVR) and ioxaglate (IOX). IPR and IVR are non-ionic CM, IOX is an ionic CM. Different parameters of renal function were determined before and 6, 24, 48, 72 hrs after angiography in 45 patients: 15 patients were examined with IPR, 15 with IVR and 15 with IOX. Glomerular effects--Plasma creatinine increased slightly at the 24th hour after IVR and IOX and at 48 hours after IOP. A significant increase in plasma beta2-microglobulin was observed, at the same time, only after IOX. A significant decrease in creatinine clearance was found at 6 hours after IOX. No significant variations in glomerular filtration rate (GFR) and in effective renal plasma flow were found at 48 hours after cardiac angiography; while filtration fraction was significantly reduced after IOP and IOX. Tubular effects--A marked decrease in sodium clearance and a relevant increase of urinary activities of different tubular enzymes were found after cardiac angiography with all CM, but were more evident after the ionic CM IOX, than after the two non-ionic agents. These tubular effects reached the maximum between 6 and 24 hours and returned to baseline within 72 hrs after cardiac angiography. In conclusion, slight glomerular effects were observed mainly after IOX. A reversible tubular malfunction was found with the three low-osmolar CM and was more evident after ionic CM IOX. thus suggesting that other mechanisms, besides osmolarity, play a role in tubular toxicity due to CM. In no patient did the glomerular and tubular effects of CM have a clinical relevance.

Effect of iomeprol on renal function immediately after abdominal angiography

PURPOSE

To investigate the acute renal effects of 2 osmolality levels of iomeprol in a double-blind, randomized, parallel-group study.

MATERIAL AND METHODS

Ten patients received iomeprol 300 mg I/ml, and a further 10 received iomeprol 400 mg I/ml intraarterially at routine abdominal angiography. The mean volume of contrast medium administered was 227.3+/-59.3 ml in the iomeprol 300 group and 221.5+/-30.9 ml in the iomeprol 400 group.

RESULTS

The urinary minute volume increased immediately after angiography, but tended to return to baseline 120 min after the examination. No significant decrease in creatinine clearance occurred; however, the fraction excretion of sodium increased immediately after angiography. The lysosomal enzyme N-acetyl-beta-glucosaminidase and the proximal tubular brush border enzyme gamma-glutamyl transferase increased up to 120 min after the procedure. Free water clearance was negative during each study period. No statistical differences in any parameter were evident between these 2 groups.

CONCLUSION

These results suggest that osmotic diuresis and its acute effect on proximal tubular function are induced by the administration of iomeprol, but that these changes are reversible.

Tubular toxicity is the main renal effect of contrast media

The aim of this study is to evaluate the effects of contrast media on both tubular and glomerular function. Different parameters of tubular and glomerular function were determined before and at 1, 3, and 5 days after the intravascular administration of contrast media in 100 adult renal patients (plasma creatinine 0.6-10.8 mg/dL, mean: 1.3). Urinary activities of five tubular enzymes (alanine aminopeptidase, gamma-glutamyltransferase, alkaline phosphatase, lactate dehydrogenase, N-acetyl-beta-D-glucosaminidase) increased significantly on the first day after the administration of contrast media, indicating a tubular damage. Glomerular filtration rate and the conventional tests of glomerular function (plasma creatinine, creatinine clearance, and urinary proteins) presented only slight variations after the administration of contrast media. In conclusion, contrast media principally affected the renal tubule (as demonstrated by enzymuria), while their effects on glomerular function were very mild.

Glomerular and tubular effects of contrast media diatrizoate and iopromide

The aim of this study is to evaluate the nephrotoxicity of two contrast media (CM), with different physicochemical characteristics: diatrizoate (ionic high-osmolar), iopromide (nonionic low-osmolar). Intravenous urography was performed in 34 patients: 17 were examined with diatrizoate and 17 with iopromide, randomly assigned. Different parameters of glomerular and tubular function were measured before and at 6, 24, and 48 h after urography. Both contrast media induced a reversible increase of urine enzymes, which was significantly higher after diatrizoate. In particular, diatrizoate determined a relevant increase of brush border enzymes gamma-glutamyltransferase (GGT) and alkaline phosphatase (ALP) and of cytosolic enzyme lactate dehydrogenase (LDH), while, after iopromide increases of urinary enzymes were less evident and were significant only for GGT and ALP. In addition, diatrizoate affected other tubular functions (clearances of phosphorus and uric acid) and slightly decreased glomerular function in a few patients. In no case did these glomerular and tubular effects have a clinical relevance. In conclusion, the nonionic low-osmolar contrast medium iopromide appeared less nephrotoxic than diatrizoate. The cost-benefit ratio needs further examination.

Effects on renal haemodynamics and tubular function of the contrast medium Ioxaglate in renal transplant patients

The aim of this study was to evaluate the effects of Ioxaglate on renal haemodynamics and tubular function in renal transplant patients at increased risk of nephrotoxicity. 21 patients undergoing either intravenous pyelography or arteriography with Ioxaglate were studied. Renal clearance studies were carried out 1 day before and 1 day after administration of Ioxaglate (173 +/- 37 ml) injected into each patient. None experienced any adverse reaction. Mean serum creatinine, glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and urinary NAG excretion were unaltered by ioxaglate. No patient suffered a nephrotoxic reaction or acute oliguria that required dialysis as a result of the administration of contrast material. In the subset of seven patients receiving cyclosporine the same results were observed. In the subset of 10 patients with a GFR lower than 60 ml/min before injection of Ioxaglate were also observed no significant change in mean GFR, ERPF and urinary NAG excretion. Only two patients had a transient decrease of GFR of between 10 and 20%. The results of this study show that the ionic, low osmolar contrast medium ioxaglate may be used safely in patients with a renal transplant thus extending previous data obtained in patients with chronic renal failure.

Infrainguinal revascularization in the diabetic patient

This article reviews the epidemiological, anatomical and physiological background to infrainguinal arterial reconstruction in the diabetic patient. There is no firm evidence in the literature for the existence of a surgically significant occlusive 'small-vessel' disease in diabetic patients, either as an aetiological component in the pathogenesis of diabetic foot lesions or as a factor limiting the success of infrainguinal bypass grafting. Recent published results of infrainguinal vascular reconstruction in patients with diabetes are reviewed. These are encouraging; early aggressive treatment of lower-limb occlusive disease may be warranted in the diabetic patient.

Hepatic and renal dysfunction following nafcillin administration

OBJECTIVE

To review four cases of combined hepatic and renal toxicity that may be associated with the administration of nafcillin in adults. This type of adverse event with the use of nafcillin has not been previously documented in the literature.

DATA SOURCES

References from pertinent articles are identified throughout the text.

DATA SYNTHESIS

Nafcillin is a widely used penicillinase-resistant penicillin. In four patients receiving nafcillin doses greater than 9 g/24 hours, changes in renal and hepatic function markers were noted within 72 hours of the initiation of nafcillin therapy. Laboratory values returned toward baseline when nafcillin therapy was discontinued. Elevations in blood urea nitrogen, creatinine, total bilirubin, and lactate dehydrogenase have been previously described in the literature for penicillin-like agents other than nafcillin. The exact mechanism for such toxicities as well as patient risk factors have not been clearly established.

CONCLUSIONS

Caution should be taken when initiating nafcillin therapy. Evaluation of renal and liver function tests prior to initiating nafcillin therapy and within the first 72 hours appears warranted. If hepatic and/or renal toxicity is observed, discontinuation of nafcillin should be considered.

A randomized comparison of the nephrotoxicity of iopamidol and diatrizoate in high risk patients undergoing cardiac angiography

Three hundred seven high risk patients with renal impairment (serum creatinine greater than or equal to 1.5 mg/dl) were randomized in a double-blind manner to either iopamidol (a nonionic, low osmolar radiocontrast agent) or diatrizoate (a conventional radiocontrast agent) at cardiac angiography with subsequent follow-up study of renal function. Baseline clinical and angiographic variables were similar in the iopamidol (n = 155) and diatrizoate (n = 152) groups. Change in renal function after angiography was less pronounced with iopamidol compared with diatrizoate as measured by mean ( +/- SD) increase in 24 h serum creatinine (0.11 +/- 0.2 versus 0.22 +/- 0.26 mg/dl, p less than 0.001), mean maximal increase in serum creatinine (0.2 +/- 0.44 versus 0.38 +/- 0.73 mg/dl, p less than 0.0001) and percent of patients with a maximal increase in serum creatinine greater than 0.5 mg/dl (8% versus 19%, p less than 0.01). Such differences could not be documented in diabetic patients using insulin. There was no significant difference between agents in the number of patients developing clinically severe acute renal dysfunction. It is concluded that iopamidol is less nephrotoxic than diatrizoate in high risk patients at cardiac angiography. However, the difference in nephrotoxicity is small, of no major clinical significance in the majority of high risk patients and could not be documented in insulin-using diabetic patients. Iopamidol may be the preferred agent in certain patients with advanced renal impairment, but further study is warranted.

Intravenous urography with iopamidol in children with reflux and obstructive nephropathy: effects on glomerular and tubular functions and the renin-angiotensin-aldosterone system

Twenty-seven children [2 with chronic renal failure (CRF)] with reflux or obstructive nephropathy underwent intravenous urography with iopamidol 370, a nonionic contrast medium 1 (CM), osmolality 796 mosmol/kg, for renal growth evaluation. Mean iopamidol dosing was 1.69 ml/kg (range 1.22-2.42); the 2 children with CRF received 2 and 2.42 ml/kg respectively. One hour after infusion a significant decrease in haematocrit, haemoglobin, plasma sodium (Na+), chloride (Cl-), renin activity and aldosterone was observed, consistent with a possible plasma volume expansion due to the slightly hypertonic CM. At the same time there was a significant increase in fractional excretion of Na+, Cl- and potassium, probably due to the haemodynamic effects and tubular response to a substance acting as on osmotic diuretic. The -24 to +48 h monitoring of albuminuria, beta-2-microglobulin excretion, and in 4 children excretion of N-acetyl-beta-glucosaminidase and alanine-aminopeptidase did not show any relevant nephrotoxicity. No untoward effect of clinical relevance was observed.

Effects on renal hemodynamics and tubular function of the contrast medium iohexol in renal patients

Renal function was assessed in 20 (11 female and 9 male, age 21-76 years, mean 53) renal patients with a creatinine clearance 25-145 ml/min, mean 95, to evaluate the effects of iohexol, a non-ionic low-osmolar contrast medium. Intravenous urography was performed in 16 patients and computed body tomography in 4, using a dose of iohexol ranged between 0.6-3.3 (mean 1.17) g/kg b.w. Different parameters of renal function were determined in the week preceding and 1, 3 and 5 days after the administration of iohexol. The principal renal effect of iohexol was an increase of urinary alanine aminopeptidase, gamma-glutamyltransferase, lactate dehydrogenase, alkaline phosphatase and N-acetyl-beta-D-glucosaminidase. The maximum increase of enzymuria was observed on day 1 after the administration of iohexol. In most cases enzymes returned to base-line values within 3 days. No relevant variation of renal hemodynamics (glomerular filtration rate and effective renal plasma flow) was observed after iohexol. In conclusion, iohexol can increase of urinary enzymes, but the effect is rapidly reversible and is not accompanied by a clinically significant impairment of renal hemodynamics.

Renal failure following radiologic procedures

Radiologic procedures that employ intravascular contrast material with or without angiography may lead to renal failure. In procedures that use intravenous contrast alone, the mechanism of renal injury is not precisely known, but direct toxicity to renal tubular cells is likely to be a major factor. Ionic and nonionic contrast agents are both capable of causing this adverse reaction. Renal failure occurring during angiography may also be secondary to the effects of radiocontrast, but the additional possibility that micro cholesterol emboli have been dislodged from atheroma located on the intima of large vessels must be considered. The acute or subacute development of renal failure in the presence of skin changes (livido reticularis), hypertension, multiple organ failure or dysfunction, and a fatal outcome favors the later diagnosis.

Contrast-associated nephropathy

Contrast nephropathy can be defined as an acute impairment of renal function that follows exposure to radiocontrast materials and for which alternative explanations for renal impairment have been eliminated. Based on reported studies, the incidence of contrast associated nephropathy (CAN) varies from 0 to 22%. This wide variation can be traced to differences in study design and the criteria used to designate significant renal impairment. Irrespective of the exact incidence, 2 defined risk factors have been identified: preexisting renal disease and diabetes mellitus. Whereas preexisting renal insufficiency is the single most influential risk factor for CAN, when diabetes coexists the incidence approaches 100%. The clinical presentation of CAN is distinct, having a temporal relation between the performance of the contrast study in the high-risk patient and the onset of an increase in serum creatinine levels within the next 24 hours. Serum creatinine values greater than 50% of baseline or rising 1 mg/dl or more is diagnostic. The peak serum creatinine level occurs within 3 to 5 days of the contrast study and oliguria is associated in approximately 30% of the cases. Monitoring serum creatinine is the most useful clinical procedure in high-risk patients after angiography. At least 5 potential pathophysiologic mechanisms of CAN have been proposed: interference with renal perfusion, altered glomerular perm-selectivity, direct tubular injury, intraluminal obstruction, and immunologic mechanisms. Support for each mechanism, either singularly or in combination, can be found in published reports; however, none has achieved universal acceptance. The single most important clinical axiom regarding the prevention and management of CAN is, "Always use the least invasive diagnostic procedure available."(ABSTRACT TRUNCATED AT 250 WORDS)

Low-osmolality contrast media: a current perspective

Intravascular radiographic contrast media play a major role in diagnostic imaging. Recently, low-osmolality contrast media (LOCM) have become available in the United States. Because of their lower osmolality, these new agents cause fewer undesirable physiologic effects and fewer adverse reactions than do conventional agents after intravascular administration. Unfortunately, the cost of LOCM is substantially higher than the cost of conventional contrast media. Appropriate use of these newer, more expensive contrast agents must be based on a thorough knowledge and understanding of their chemistry, physiologic features, and relative safety. Some questions remain about these new agents. Further studies are needed to determine the nephrotoxicity of LOCM relative to that of conventional agents. In addition, LOCM have less anticoagulant capacity than do the conventional media; therefore, clotting may occur when the LOCM and blood mix in syringes and small catheters. This potential decrease in anticoagulation and its clinical implications should be further investigated. Finally, the mortality rate associated with use of LOCM needs to be determined in future studies in large numbers of patients.