Contrast agent nephrotoxicity: comparison of ionic and nonionic contrast agents

Urinary Protein Excretion following Intravenously Administered Ionic and Non-Ionic Contrast Media in Man

Urinary protein excretion following intravenous administration of the radiographic contrast media (CM) diatrizoate (ionic) and iopromide (non-ionic) was examined in 20 patients with normal renal function. Neither of the two CM had any effect on the 24-h urinary excretion of albumin (a marker of glomerular proteinuria). The 24-h urinary excretion of the retinol-binding protein (a marker of low molecular weight or tubular proteinuria) and the folate binding protein, a protein localized in the brush-border membranes of the proximal tubular cells, showed a statistically significant transient increase the day after diatrizoate injection, whereas no increase was observed after iopromide. Thus, only a minimal and temporary disturbance of the renal proximal tubular function was observed after diatrizoate injection in patients with normal renal function.

Iodixanol in Cardioangiography in Patients with Coronary Artery Disease

Iodixanol is a new nonionic, dimeric contrast medium. With the addition of 18 mmol/l Na+ and 0.3 mmol/l Ca++ to iodixanol 320 mg I/ml a plasma-isotonic solution was obtained. The purpose was to evaluate the suitability of iodixanol for use in cardioangiography by determining the diagnostic efficacy, patient tolerability, and cardiac and renal side-effects. Initially, 14 patients with coronary artery disease were examined using iodixanol. A double-blind, randomized study was then performed in 72 patients, comparing iodixanol and iohexol. Serum and urine were sampled before the examination, and one and 2 days after. The diagnostic information was good and the number of adverse events low with iodixanol. The patients reported significantly less of a sensation of warmth following injection of iodixanol than iohexol. Our results also indicate that iodixanol 320 mg I/ml influences renal function to a lesser degree than does iohexol 350 mg I/ml. We therefore conclude that isotonic iodixanol is a safe contrast medium for use in cardioangiography.

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.

Iodixanol in Cardioangiography

Iodixanol (Visipaque) 320 mg I/ml, a non-ionic, dimeric, isotonic contrast medium, was compared to ioxaglate (Hexabrix) 320 mg I/ml in cardioangiography. One hundred and two patients with normal renal function were included in the study. The objectives were to evaluate safety, tolerability, radiographic efficacy and effects on renal function. Adverse events, discomfort, vital signs, clinical chemistry parameters, diagnostic information and radiographic density were recorded. Both contrast media had minor effects on the renal function parameters monitored. The patients who received iodixanol experienced fewer adverse events, significantly less discomfort and had a lower increase in heart rate than did the patients in the ioxaglate group. The radiographic efficacy was good in both groups. Iodixanol 320 mg I/ml is safe and effective for use in cardioangiography.

Clinical use of biomarkers for toxicant-induced acute kidney injury

Toxicant-induced acute kidney injury (ToxAKI) causes substantial morbidity and retards drug development. ToxAKI is relatively underexplored compared with ischemia–reperfusion injury in clinical biomarker studies. We highlight the rationale for novel AKI biomarkers in management of ToxAKI, and review the contemporary evidence supporting their clinical use. Directly-acting nephrotoxins, such as cisplatin, aminoglycosides, vancomycin and radiocontrast, remain widely used and highlight how novel biomarkers can either improve the detection of changes in glomerular filtration rate or directly signal cellular injury and structural damage. Serum cystatin C has already improved clinical risk prediction and drug dosing although its clinical use for early diagnosis awaits validation. The use of novel functional and structural biomarkers to stage ToxAKI and aid prognosis requires robust validation and better understanding of the relationship between biomarkers, morbidity and mortality. Biomarkers that illustrate the probable mechanisms and phase of ToxAKI may guide mechanism-specific diagnosis and therapy.

High-dose contrast agent administration during complex coronary angioplasty

To examine the necessity and consequences of high-dose contrast media administration during coronary angioplasty, the records of 730 consecutive patients over a 6-month period were reviewed. The 54 patients (7%) requiring contrast agent doses greater than or equal to 400 ml were examined in detail. The mean contrast dose in this group was 496 +/- 76 ml (range 400 to 785 ml). Their mean age was 63 +/- 11 years (range 36 to 83 years), 10 patients had diabetes mellitus (19%), and four patients had a baseline creatinine level greater than or equal to 1.5 mg/dl (7%). Following coronary angioplasty, the serum creatinine rose from 1.1 +/- 0.2 to 1.2 +/- 0.3 (p = 0.08). The creatinine rose greater than or equal to 0.5 mg/dl in six patients (11%) and greater than or equal to 1.0 mg/dl in one patient (2%). Five of these six patients had either diabetes mellitus, baseline renal insufficiency, or both. Oliguria was not observed. The most important procedural factors contributing to the high doses of contrast media were multilesion and multivessel angioplasty in 96% and 83% of patients, respectively, prior bypass surgery in 52%, and combined diagnostic cardiac catheterization and angioplasty in 13%. Thus renal dysfunction following high-dose contrast agent administration during complex coronary angioplasty is infrequently associated with nephrotoxicity. Whenever possible, contrast doses in patients with diabetes mellitus and renal insufficiency should be minimized.

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.