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CT Contrast and Kidneys (FAQ)

American College of Radiology Manual on Contrast Media (download pdf):

1) Do end-stage renal patients need urgent dialysis after a CT scan with IV contrast? No

“Most low-osmolality iodinated contrast media are not protein-bound, have relatively low molecular weights, and are readily cleared by dialysis. Unless an unusually large volume of contrast medium is administered, or there is substantial underlying cardiac dysfunction, there is no need for urgent dialysis after intravascular iodinated contrast medium administration.” pg 42, v10.3, May 31,2017

2) Does an increase in serum creatinine within 48 hrs of CT contrast injection qualify as “Contrast Induced Nephropathy” ? No

“Post-contrast acute kidney injury (PC-AKI) is a general term used to describe a sudden deterioration in renal function that occurs within 48 hours following the intravascular administration of iodinated contrast medium. PC-AKI may occur regardless of whether the contrast medium was the cause of the deterioration [1-12]. PC-AKI is a correlative diagnosis. Contrast-induced nephropathy (CIN) is a specific term used to describe a sudden deterioration in renal function that is caused by the intravascular administration of iodinated contrast medium; therefore, CIN is a subgroup of PC-AKI [1-12]. CIN is a causative diagnosis.” pg 35, v10.3, May 31,2017

3) Are there standard criteria for diagnosing contrast induced nephropathy? No (pg36)

4) Is contrast induced nephropathy (CIN) common? No

“Four large studies released in 2013 and 2014 (each with >10,000 patients) have addressed selection bias in the unenhanced CT population through use of propensity score adjustment and propensity score matching [3,4,7,9]. Although the conclusions from these studies differ somewhat, all four have shown that CIN is much less common than previously believed. In patients with a stable baseline eGFR ≥45 mL / min/1.73m2, IV iodinated contrast media are not an independent nephrotoxic risk factor [3,4,7,9], and in patients with a stable baseline eGFR 30-44 mL / min/1.73m2, IV iodinated contrast media are either not nephrotoxic or rarely so [3,4,7,9].” pg 37, v10.3, May 31,2017

5) Is there any population believed to be at risk from contrast media? Possibly

“Despite this common ground, there are differences among these studies [3,4,7,9] in the covariates chosen for inclusion, the method of controlling baseline renal function instability, the definitions of AKI, and the nuances of the statistical methodology. These differences likely explain the different conclusions drawn between these studies for patients with Stage IV and Stage V chronic kidney disease (eGFR <30 mL / min/1.73m2). In particular, two propensity-score matched studies [3,4] have shown that IV iodinated contrast material is an independent nephrotoxic risk factor in patients with Stage IV and Stage V chronic kidney disease, while two others were unable to find such evidence [7,9].” pg 38, v10.3, May 31,2017

6) What can help mitigate potential CIN? (pg 41)

  • Volume expansion – Possibly
  • Sodium Bicarbonate – No
  • N-actylcysteine – No
  • Mannitol or Furosemide – No

7) Can a patient receive more than one contrast load in 24 hours? Yes

“We do not believe that there is sufficient evidence to specifically endorse the decision to withhold a repeat contrast medium injection until more than 24 hours have passed since the prior injection, nor to recommend a specific threshold of contrast medium volume beyond which additional contrast media should not be given within a 24-hour period.” pg 41, v10.3, May 31,2017

Other Recent Evidence:

Aycock RD, Westafer LM, Boxen JL, Majlesi N, Schoenfeld EM, Bannuru RR. Acute Kidney Injury After Computed Tomography: A Meta-analysis. Ann Emerg Med. 2018;71(1):44-53.e4. PubMed , Open Access

This systematic review and meta-analysis of 28 published studies (literature to date), including 107,335 patients, focused on:

  • Rates of renal insufficiency
  • Need for renal replacement therapy
  • Mortality in patients who received intravenous contrast versus those who received no contrast

and concluded the following:

“We found no significant differences in our principal study outcomes between patients receiving contrast-enhanced CT versus those receiving noncontrast CT. Given similar frequencies of acute kidney injury in patients receiving noncontrast CT, other patient- and illness-level factors, rather than the use of contrast material, likely contribute to the development of acute kidney injury.”

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