Rationale:

Serum creatinine (sCr) levels are a quick way to estimate whether there is kidney disease in patients with risk factors for acute or chronic kidney disease. In patients which chronic kidney disease, sCr levels provide an estimate of the degree of kidney dysfunction. Acute or chronic kidney disease may be a risk factor for contrast-induced acute kidney injury (AKI), although recent data raises questions about this relationship.

The estimated glomerular filtration rate (eGFR), obtained by the National Kidney Foundation GFR calculator, is more accurate in guiding clinical decision making than the sCr level.

Inpatients

  • All inpatients must have a serum creatinine within 24 hours prior to IV contrast administration, regardless of the presence of an “acute illness” or “risk factors” for post-contrast AKI.
  • Obtain the eGFR, either directly from the UW lab results tab in the EHR or with point of care (POC) testing plus the online calculator at (https://www.kidney.org/professionals/kdoqi/gfr_calculator). The sCr level in UW laboratories is reported in mg/dL.
Timing of sCr measurement prior to intravenous contrast: Inpatients
  Risk Factors No Risk Factors
Duration since sCr measurement 24 hours 24 hours

Outpatients

Serum creatinine is required before the examination in the following circumstances.

  1. Risk factors: If the patient has any of the risk factors for post-contrast AKI questions on the sCr questionnaire (see appendix below).
  2. Acute illness: If the patient has a clinical condition likely to cause acute kidney injury or a recent elevation in the sCr level (see appendix below).

 

  • Obtain the eGFR, either directly from the UW lab results tab (in Epic), or with point of care (POC) testing plus the online calculator at (https://www.kidney.org/professionals/kdoqi/gfr_calculator). The sCr level in UW laboratories is reported in mg/dL.
Timing of sCr measurement prior to intravenous contrast: Outpatients
  Risk Factors No Risk Factors
Acute Illness 24 hours 24 hours
No acute illness 14 days Not required.

Emergency Department Patients

Serum creatinine required before the examination in the following circumstances.

  1. Risk factors: If the patient has any of the risk factors for contrast-induced AKI (see appendix below).
  2. Acute illness: If the patient has a clinical condition likely to cause acute kidney disease (see appendix below).

 

  • Obtain the eGFR, either directly from the UW lab results tab in EHR, or with point of care (POC) testing plus the online calculator at (https://www.kidney.org/professionals/kdoqi/gfr_calculator). The sCr level in UW laboratories is reported in mg / dL.
Timing of sCr measurement prior to intravenous contrast: ED Patients
Risk Factors No Risk Factors
Acute Illness 24 hours 24 hours
No acute illness 14 days Not required.

Very Urgent Patients

In medical emergencies (example e.g. the medically unstable or non-responsive multi-trauma patient, stroke patients, sudden cardiac death), the delay caused by obtaining a comprehensive medical history and / or a serum creatinine level may put the patient at higher risk of an adverse outcome than administering contrast without a full history or serum creatinine level. In these circumstances, a supervising physician can elect to administer contrast without a full history or serum creatinine level.

Time between IV iodinated contrast scans should be as follows:

Waiting > 24 hours between contrast injections is not necessary if the delay will adversely affect patient care and the patient has normal renal function and does not have the risk factors for AKI (appendix below). Otherwise, consider waiting at least 24 hours between iodinated contrast injections if it is for nonurgent indications, however, there is insufficient evidence to support withholding contrast until more than 24 hours have passed since the prior injection if the benefits outweigh the risks.

Appendix

‘Acute’ illness” refers to the patient becoming unwell within the last week with a disease likely to affect kidney function. This includes dehydration, sepsis, vomiting, diarrhea, unable to eat or drink for 24 hours or more, prolonged level of reduced consciousness, or suspected acute kidney or cardiac disease. In addition, evidence in sCr increase to ³ 1.5 x baseline within a week. Chronic illnesses such as cancer are not considered acute illnesses.

Risk Factors / Screening Questionnaire Questions:

Although there is conflicting evidence regarding which comorbidities increase the risk of contrast-induced AKI, the following risk factors are considered to warrant a pre-contrast serum creatinine.

  • Personal history of “kidney disease”, including dialysis, kidney mass, kidney cancer, kidney failure (either chronic or prior acute) or renal transplantation.
  • Personal history of liver cirrhosis AND is a liver transplant recipient candidate.
  • Taking medications of concern, including but not limited to:
    • Metformin

 

Updated October 2022.