Not as strong as one might expect with an increasing number of investigators questioning the causative role of IV contrast in precipitating CIN.

A 2013 meta-analysis involving observational—mostly retrospective— studies concluded that the risks of AKI, death, and dialysis were similar between IV contrast and non-contrast patients, including those with diabetes or underlying renal insufficiency¹.

Two retrospective studies^2,3 designed to control for a variety of factors that may affect the risk of AKI by propensity matching found divergent results with the larger and better designed study finding no significant difference in AKI between the 2 groups³. A 2017 retrospective cohort analysis of emergency department patients utilizing a similar propensity-score analysis also failed to find a difference in post-CT AKI between those receiving and not receiving IV contrast⁴.

Further shedding doubt on the role of IV contrast in causing AKI, a study involving patients with chronic kidney disease found no difference in the rates of excretion of 2 biomarkers of AKI (neutrophil gelatinase-associated lipocalin-NGAL, and kidney injury molecule-1-KIM-1) between patients with and without presumed CIN⁵.

This is not to say that IV CIN does not exist. Among many findings, in vitro and animal studies have demonstrated that iodinated contrast media exerts cytotoxic effects on renal tubular epithelial cells and promotes hemodynamic changes through renal vasoconstriction to severe renal damage and cellular apoptosis (6). However, some have have criticized experimental animal studies supporting the existence of CIN due to their poor applicability to human renal disease. ¹

After all these years, it’s still important to keep an open mind about the pathophysiology and epidemiology of CIN. Stay tuned!

Fun pearl: Did you know that the first case of CIN was described in a patient with multiple myeloma undergoing IV pyelography (before the CT era)?

Liked this post? Download the app on your smart phone and sign up below to catch future pearls right into your inbox, all for free!

References

1. McDonald JS, McDonald RJ, Comin J, et al. Frequency of acute kidney injury following intravenous contrast medium administration: a systematic review and meta-analysis. Radiology. 2013;267(1):119-128. https://www.ncbi.nlm.nih.gov/pubmed/23319662
2. Davenport MS, Khalatbari S, Dillman JR, et al. Contrast material-induced nephrotoxicity and intravenous low-osmolality iodinated contrast material. Radiology. 2013;267(1):94-105. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3606541/pdf/121394.pdf
3. McDonald RJ, McDonald JS, Bida JP, et al. Intravenous contrast material-induced nephropathy: causal or coincident phenomenon? Radiology 2013;267:106-18. https://www.ncbi.nlm.nih.gov/pubmed/23360742
4. Hinson JS, Ehmann MR, Fine DM, et al. Risk of acute kidney injury after intravenous contrast media administration. Ann Emerg Med 2017; 69:577-586. https://www.ncbi.nlm.nih.gov/pubmed/28131489
5. Kooiman J, van de Peppel WR, Sijpkens YWJ, et al. No increase in kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin excretion following intravenous contrast enhanced-CT. Eur Radio 2015;25:1926-34. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4457910/pdf/330_2015_Article_3624.pdf
6. Mamoulakis C, Fragkiadoulaki I, Karkala P, et al. Contrast-induced nephropathy in an animal model: evaluation of novel biomarkers in blood and tissue samples. Toxicol Rep 2019;6:395-400. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6506864/ 

Original contribution by Ginger Jiang, Medical Student, Harvard Medical School

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers, Mass General Hospital, Harvard Medical School or its affiliated institutions. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!