Contrast-induced nephropathy

Dr Dan J Bell and Dr Jeremy Jones et al.

Contrast-induced nephropathy (CIN) is the third most common cause of all hospital-acquired acute renal failure and accounts for ~10% of all cases. There is still an ongoing debate regarding its occurrence after intravenous contrast medium administration because most of the cases occur after intra-arterial administration of contrast for angiographic procedures. Even though the incidence is 5% after intravenous contrast administration 5.

So far there are no standards to report the CIN, therefore, the definition used in the literature is variable.

The definition of contrast nephropathy relies on serial plasma creatinine concentrations. A baseline creatinine level should be obtained before the procedure. Estimated glomerular filtration rate (eGFR) has been used for the assessment of renal function before intravenous contrast injection. This is calculated from the patient's age, race, sex and serum creatinine level. Online calculators are also available to assist in easily calculating eGFR.

Post-contrast peak effect on creatinine occurs between 48 and 72 hours:  

  • relative: 25% rise in creatinine over baseline
  • absolute: rise of greater than 44 μmol/L

Contrast-induced acute kidney injury (CI-AKI) has now also been described in which injury or damage to the kidney has taken place, but is subclinical in that no measurable reduction in renal filtration is apparent 4.

Risk for most normal individuals with no risk factors is based on baseline renal function

  • low: Cr <130 μmol/L or CrCl >60 mL/min
  • medium: Cr 130-200 μmol/L or CrCl 30-60 mL/min
  • high: Cr >200 μmol/L or CrCl <30 mL/min

For risk stratification using eGFR:

  • very low risk: >60 mL/min
  • low risk: 45-59 mL/min
  • moderate: 30-45 mL/min
  • high risk: <30 mL/min

The Royal Australian and New Zealand College of Radiologists recommends that patients in the emergency setting that require contrast media for computed tomographic examinations should have no delay to scan time due to renal function testing 6.

However, if they are going to have an investigation with more than 300 mL of iodinated contrast or two studies less than 72 hours apart, their risk is elevated to the medium group irrespective of their baseline renal function.

Patients with risk factors are automatically elevated to higher risk groups

The most important factor is adequate pre-hydration and assessment of renal function. Risk stratification helps to determine what the most appropriate preparation is, and protocols will vary from institution to institution:

  • low: oral fluids only
  • medium
    • IV 0.9% normal saline for 12 hours before and after the procedure
    • at 48 hours: if the creatinine is 25% above baseline, a further check five days post-procedure should be taken
  • high
    • IV 0.9% normal saline for 12 hours before and after the procedure
    • N-acetylcysteine (NAC) 600 mg orally bd (three days before the procedure and one day afterwards)
    • check creatinine at baseline, 48 hours, five days and ten days
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Article information

rID: 10252
Section: Physics
Tag: cases
Synonyms or Alternate Spellings:
  • Contrast nephropathy
  • Contrast-induced acute kidney injury (CI-AKI)
  • Contrast mediated nephrotoxicity

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