What is the risk of contrast-induced nephropathy (CIN) in a patient with impaired renal function, specifically a glomerular filtration rate (GFR) of 25, undergoing a computed tomography (CT) angiogram?

From the Guidelines

The risk of contrast-induced nephropathy (CIN) is significantly elevated in a patient with a GFR of 25 undergoing CT angiography, with an estimated risk of approximately 10-20%. For this patient, I would recommend careful consideration of whether the CT angiogram is absolutely necessary. If the study must proceed, preventive measures should include:

• Pre-procedure hydration with isotonic saline (1 mL/kg/hr for 6-12 hours before and after the procedure) 1
• Using the minimum necessary dose of iso-osmolar or low-osmolar contrast media 1
• Temporarily discontinuing nephrotoxic medications like NSAIDs and metformin 48 hours before the procedure 1
• N-acetylcysteine (600-1200 mg orally twice daily the day before and day of the procedure) may be considered, though evidence for its effectiveness is mixed 1 The patient's renal function should be monitored with serum creatinine measurements at 24-48 hours after the procedure. CIN risk is elevated because the contrast media causes renal vasoconstriction and direct tubular toxicity, which can worsen existing kidney dysfunction, particularly in patients with GFR below 30 mL/min/1.73m². Some key points to consider:
• The use of low-osmolar or iso-osmolar contrast media is recommended for patients with moderate-to-severe CKD 1
• The volume of contrast media should be minimized 1
• Hydration with isotonic saline is recommended for patients with moderate-to-severe CKD 1
• Short-term, high-dose statin therapy may be considered for patients at high risk of CIN 1

From the FDA Drug Label

1. 3 Contrast-Induced Acute Kidney Injury Acute kidney injury, including renal failure, may occur after iodixanol administration Risk factors include: pre-existing renal impairment, dehydration, diabetes mellitus, congestive heart failure, advanced vascular disease, elderly age, concomitant use of nephrotoxic or diuretic medications, multiple myeloma/paraproteinaceous diseases, repetitive and/or large doses of an iodinated contrast agent.

The risk of contrast-induced nephropathy in a patient with a GFR of 25 is increased due to the presence of pre-existing renal impairment, which is a risk factor for contrast-induced acute kidney injury.

• Key risk factors for this patient include:
  • Pre-existing renal impairment (GFR of 25)
  • Potential for dehydration
  • Potential for concomitant use of nephrotoxic or diuretic medications To minimize the risk, it is recommended to use the lowest necessary dose of iodixanol and adequately hydrate the patient prior to and following iodixanol administration 2.

From the Research

Risk of Contrast-Induced Nephropathy in CT Angiogram

• The risk of contrast-induced nephropathy (CIN) is a significant concern in patients with pre-existing renal impairment, such as those with a glomerular filtration rate (GFR) of 25 3, 4.
• CIN is commonly defined as a decline in kidney function occurring after administration of iodinated contrast agents, and it can lead to more permanent renal insufficiency, dialysis, and death 3.
• The incidence of CIN has been reported to range from 0% to 24%, depending on the definition, background risk factors, type and dose of contrast medium used, and the frequency of other coexisting potential causes of acute renal failure 4.

Prevention Strategies

• Minimizing the amount of contrast administered and providing adequate hydration are the cornerstones of an effective preventative approach to reduce the risk of CIN 3, 4.
• Hydration with sodium bicarbonate has been shown to decrease the incidence of CIN compared to hydration with normal saline 5.
• The use of N-acetylcysteine (NAC) in addition to bicarbonate hydration has been investigated, but its effectiveness in preventing CIN is still unclear 6.

Patient-Specific Risk Factors

• Patients with chronic renal failure (CRF) are at higher risk of developing CIN, and those with a GFR of 25 are considered to be at high risk 6, 7.
• Other risk factors for CIN include older age, diabetes, volume depletion, sepsis, and use of nephrotoxic drugs 7.
• Careful selection of patients and avoidance of nephrotoxic agents pre- and post-procedure are crucial in preventing CIN 4.