Definition
Contrast-induced nephropathy (CIN) is an acute kidney injury following iodinated contrast, typically a rise in creatinine of 25% (or ~44 µmol/L) from baseline within 2–5 days, in the absence of another cause.
Risk factors
- Pre-existing chronic kidney disease (the strongest risk factor)
- Diabetes mellitus
- Dehydration/volume depletion
- High contrast volume and repeated studies
- Concurrent nephrotoxins (NSAIDs, aminoglycosides), heart failure, advanced age
Clinical course
- Creatinine rises over a few days and usually recovers, but can be significant in high-risk patients
- Often non-oliguric
Prevention
- Identify at-risk patients and weigh the necessity of contrast
- Intravenous hydration with isotonic fluid before and after the study — the mainstay
- Use the minimum contrast volume; avoid closely repeated studies
- Withhold nephrotoxic drugs; hold metformin around the procedure in significant renal impairment (risk of lactic acidosis if AKI ensues)
MRCP-specific traps
- Hydration is the key preventive measure; routine N-acetylcysteine is no longer recommended.
- Hold metformin in renal impairment around contrast, restarting once function is confirmed stable.
- Reassess renal function after the procedure in at-risk patients.
Summary
Contrast-induced nephropathy is an AKI 2–5 days after iodinated contrast (creatinine rise of 25% or ~44 µmol/L). Highest risk with CKD, diabetes and dehydration. Prevent with IV hydration, minimal contrast and withdrawal of nephrotoxins; hold metformin around the study in renal impairment.
nephrologyradiologyacute kidney injurymrcp part 2