Does contrast-induced nephropathy (CIN) still occur?

From the Guidelines

Contrast-induced nephropathy (CIN) still exists and is a significant concern in patients undergoing imaging studies with iodinated contrast media, particularly those with pre-existing kidney disease, diabetes, dehydration, or heart failure. The risk of CIN, also known as contrast-associated acute kidney injury (CA-AKI), can be mitigated with preventive measures such as adequate hydration with intravenous isotonic saline, minimizing contrast volume, and using iso-osmolar or low-osmolar contrast agents 1. According to the 2023 AHA/ACC/ACCP/ASPC/NLA/PCNA guideline, attempts to minimize the risk of contrast nephropathy should be made through the avoidance of nephrotoxic agents, use of adequate hydration before the administration of iodinated contrast-agent, and minimization of the volume of contrast media 1.

Some key points to consider in preventing CIN include:

• Hydration with intravenous isotonic saline (typically 1-1.5 mL/kg/hr for 3-12 hours before and after contrast exposure) is recommended 1
• Minimizing contrast volume is important to prevent contrast-induced AKI in patients undergoing angiography 1
• Using iso-osmolar or low-osmolar contrast agents may reduce the risk of CIN 1
• N-acetylcysteine has been used but shows inconsistent benefits and is not recommended for routine use 1
• High-dose statins may reduce the occurrence of contrast-induced AKI 1

The pathophysiology of CIN involves direct tubular toxicity, vasoconstriction, and oxidative stress in the kidneys 1. Most cases of CIN resolve within 7-14 days, but it can lead to permanent kidney damage in high-risk patients, making preventive measures crucial 1. Therefore, it is essential to prioritize preventive measures, such as hydration and minimizing contrast volume, to reduce the risk of CIN in patients undergoing imaging studies with iodinated contrast media.

From the Research

Contrast Nephropathy Overview

• Contrast-induced nephropathy (CIN) is a condition associated with significant economic and clinical consequences, including prolonged hospitalization, the requirement for dialysis, and an increased risk of death 2.
• CIN is usually defined as an increase in serum creatinine concentration >0.5 mg/dl or 25% above the baseline level within 48 h 3.

Risk Factors for Contrast Nephropathy

• Important patient-related risk factors for CIN include chronic kidney disease, diabetes mellitus, heart failure, older age, anemia, and left ventricular systolic dysfunction 2.
• Non-patient-related risk factors include high-osmolar contrast, ionic contrast, contrast viscosity, and contrast volume 2.
• Patients with estimated glomerular filtration rates (eGFRs) < 30 mL/min/1.73m2 are at high risk for CIN, while patients with eGFRs ≥ 45 mL/min/1.73m2 are at negligible risk 4.

Prevention and Management of Contrast Nephropathy

• Available evidence supports the use of hydration, bicarbonate, and low volumes of iso- or low-osmolar contrast in patients at risk 2.
• N-acetylcysteine or ascorbic acid may be of value in very high-risk patients 2, 3.
• Adequate hydration combined with isosorbide dinitrate can safely and effectively reduce the risk of CIN in patients with chronic kidney disease and congestive heart failure 5.
• Intravenous hydration (saline 0.45%, if tolerated 0.9% at a rate of 1 ml/kg/h) 12 h before and after contrast exposure is advisable 3.

Current State of Contrast Nephropathy

• Recent observational studies have questioned the prevalence and severity of CIN following intravenous contrast exposure 4, 6.
• The true risk attributable to intravenous contrast media for the occurrence of CIN has become debatable 6.
• Further research is needed to correctly identify higher-risk patients and test therapies in the setting of large well-powered clinical trials 2.