Contrast-induced nephropathy

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Contrast-induced nephropathy
SpecialtyNephrology, radiology

Contrast-induced nephropathy (CIN) is a purported form of kidney damage in which there has been recent exposure to medical imaging contrast material without another clear cause for the acute kidney injury.

Despite extensive speculation, the actual occurrence of contrast-induced nephropathy has not been demonstrated in the literature.[1]

Analysis of observational studies has shown that radiocontrast use in CT scanning is not causally related to changes in kidney function.[2]


Given the increasing doubts about the contribution of radiocontrast to acute kidney injury, the American College of Radiology has proposed the name contrast-associated acute kidney injury (CA-AKI) (formerly referred to as post-contrast acute kidney injury; PC-AKI) does not imply a causal role, with the name contrast-induced acute kidney injury (CI-AKI) (formerly referred to as contrast-induced nephropathy; CIN) reserved for the rare cases where radiocontrast is likely to be causally related.[3]

Risk factors[edit]

There are multiple risk factors of contrast-induced nephropathy, whereof a 2016 review emphasized chronic kidney disease, diabetes mellitus, high blood pressure, reduced intravascular volume, and old age.[4]

Decreased kidney function[edit]

European guidelines classify a pre-existing decreased kidney function to be a risk factor of contrast-induced nephropathy in the following cases:[5]

To calculate estimated GFR from creatinine, European guidelines use the CKD-EPI formula in adults ≥ 18 years, and the revised Schwartz formula in children.[5] Swedish guidelines recommends no specific formula in children because of lack of evidence, but on the other hand recommends GFR based on cystatin C rather than creatinine in those with abnormal muscle mass or liver failure or cirrhosis.[5]

Mehran score[edit]

The Mehran score is a clinical prediction rule to estimate probability of CIN which includes the following risk factors: systolic blood pressure <80 mm Hg for at least one hour requiring inotropic support, intra-arterial balloon pump, congestive heart failure with NYHA class III or worse, history of pulmonary edema, age >75 years, hematocrit level <39% for men and <35% for women, diabetes mellitus, contrast media volume, decreased kidney function (serum creatinine level >1.5 g/dL or decreased estimated glomerular filtration rate).[6][7]

Other factors[edit]

European guidelines include the following procedure-related risk factors:[5]

  • Large doses of contrast given intra-arterially with first-pass renal exposure
  • Use of contrast agents with high osmolality (limited use today)
  • Multiple contrast injections within 48–72 h. Swedish guidelines also include gadolinium MRI contrast agents in this aspect.

Swedish guidelines list the following additional risk factors:[5]


The main alternatives in people with a risk of contrast-induced nephropathy are:[citation needed]

  • Adjustment of the radiocontrast dose
  • Treating or mitigating risk factors
  • Using no intravenous contrast for the investigation.
  • Switching to another modality such as ultrasonography or MRI.

Dose adjustment[edit]

According to European guidelines, the ratio of the contrast dose (in grams of iodine) divided by the absolute estimated glomerular filtration rate (GFR) should be less than 1.1 g/(ml/min) for intra-arterial contrast medium administration with first-pass renal exposure (not passing lungs or peripheral tissue before reaching the kidneys).[5] Swedish guidelines are more restrictive, recommending a ratio of less than 0.5 g/(ml/min) in patients with risk factors and irrespective of route of administration, and even more caution in first-pass renal exposure.[5]

Treating or mitigating risk factors[edit]

Hydration by drinking or intravenous volume expander, either before or after contrast administration, decreases the risk of contrast-induced nephropathy.[8] Evidence also supports the use of N-acetylcysteine with intravenous saline among those getting low molecular weight contrast.[9][dubious ] The use of statins with N-acetylcysteine and intravenous saline is also supported.[9]


CIN is classically defined as a serum creatinine increase of at least 25% and/or an absolute increase in serum creatinine of 0.5 mg/dL[17] after using iodine contrast agent without another clear cause for acute kidney injury,[4] but other definitions have also been used.[2]

The American College of Radiology recommends the usage of the AKIN criteria for the diagnosis of CIN or PC-AKI. The AKIN criteria states that the diagnosis is made if within 48 hours from intravascular contrast medium exposure one of the following occurs:[18]

  1. Absolute serum creatinine increase of ≥0.3 mg/dl (>26.4 µmol/L)[18]
  2. Relative serum creatinine increase of ≥50 % (≥1.5-fold above baseline)[18]
  3. Urine output reduced to ≤0.5 mL/kg/hour for at least 6 hours[18]


The mechanism of contrast-induced nephropathy is not entirely understood, but is thought to include direct damage from reactive oxygen species, contrast-induced increase in urine output, increased oxygen consumption, changes in dilation and narrowing of the blood vessels to the kidneys, and changes in urine viscosity.[citation needed]


It is unclear if CIN causes persisting decline in renal function since few studies has followed patients for more than 72 hours.[18] In one meta-analysis the decline in renal function was shown to persist in 1.1 % of the patients with CIN.[19]

Clinical relevance[edit]

Doubts regarding the significance of the phenomenon appeared in the scientific literature. Several studies have shown that intravenous contrast material administration was not associated with excess risk of acute kidney injury, dialysis, or death, even among patients with comorbidities reported to predispose them to nephrotoxicity.[1] Moreover, hydration, the most established prevention measure to prevent contrast-induced nephropathy was shown to be ineffective in the POSEIDON trial,[20] raising further doubts regarding the significance of this disease state.[21] A meta-analysis of 28 studies of AKI after CT with radiocontrast showed no causal relationship between the use of radiocontrast and AKI.[2]


  1. ^ a b McDonald, Robert; McDonald, Jennifer S.; Carter, Rickey E.; Hartman, Robert P.; Katzberg, Richard W.; Kallmes, David F.; Williamson, Eric E. (December 2014). "Intravenous Contrast Material Exposure Is Not an Independent Risk Factor for Dialysis or Mortality". Radiology. 273 (3): 714–725. doi:10.1148/radiol.14132418. PMID 25203000.
  2. ^ a b c Aycock, Ryan D.; Westafer, Lauren M.; Boxen, Jennifer L.; Majlesi, Nima; Schoenfeld, Elizabeth M.; Bannuru, Raveendhara R. (August 2017). "Acute Kidney Injury After Computed Tomography: A Meta-analysis". Annals of Emergency Medicine. 71 (1): 44–53.e4. doi:10.1016/j.annemergmed.2017.06.041. PMID 28811122. S2CID 27167779.
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  5. ^ a b c d e f g Nyman, Ulf; Ahlkvist, Joanna; Aspelin, Peter; Brismar, Torkel; Frid, Anders; Hellström, Mikael; Liss, Per; Sterner, Gunnar; Leander, Peter (2018). "Preventing contrast medium-induced acute kidney injury". European Radiology. 28 (12): 5384–5395. doi:10.1007/s00330-018-5678-6. ISSN 0938-7994. PMID 30132106. S2CID 52057355.
  6. ^ Mehran R, Aymong ED, Nikolsky E, et al. (2004). "A simple risk score for prediction of contrast-induced nephropathy after percutaneous coronary intervention: development and initial validation". J. Am. Coll. Cardiol. 44 (7): 1393–9. doi:10.1016/j.jacc.2004.06.068. PMID 15464318.
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  11. ^ Bagshaw SM, Ghali WA (2005). "Theophylline for prevention of contrast-induced nephropathy: a systematic review and meta-analysis". Arch. Intern. Med. 165 (10): 1087–93. doi:10.1001/archinte.165.10.1087. PMID 15911721.
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  13. ^ Kellum J, Leblanc M, Venkataraman R (2006). "Renal failure (acute)". Clinical Evidence (15): 1191–212. PMID 16973048.
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  15. ^ Putzu, Alessandro; Berto, Martina Boscolo; Belletti, Alessandro; Pasotti, Elena; Cassina, Tiziano; Moccetti, Tiziano; Pedrazzini, Giovanni (2017). "Prevention of Contrast-Induced Acute Kidney Injury by Furosemide With Matched Hydration in Patients Undergoing Interventional Procedures". JACC: Cardiovascular Interventions. 10 (4): 355–363. doi:10.1016/j.jcin.2016.11.006. PMID 28231903.
  16. ^ Mattathil, Stephanie; Ghumman, Saad; Weinerman, Jonathan; Prasad, Anand (2017-10-01). "Use of the RenalGuard system to prevent contrast-induced AKI: A meta-analysis". Journal of Interventional Cardiology. 30 (5): 480–487. doi:10.1111/joic.12417. ISSN 1540-8183. PMID 28870002. S2CID 27646564.
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  18. ^ a b c d e Ellis, JH; Davenport, MS; Dillman, JR; Hartman, RP; Herts, BR; Jafri, SZ; Kolbe, AB; Laroia, A; Cohan, RH; MacDonald, RJ; Needleman, L; Newhouse, JH; Pahade, JK; Sirlin, CB; Wang, CL; Wasserman, N; Weinreb, JC (2017). ACR Manual on Contrast Media. American College of Radiology. pp. 35–46. ISBN 978-1-55903-012-0. Retrieved 20 November 2020.
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