Approach to intravenous gadolinium use in patients with impaired kidney function
The relative risk to benefit of intravenous gadolinium in patients with severely impaired kidney function should be carefully considered by the referring physician and radiologist with input from a nephrologist if necessary. Particular caution should be considered in patients with acute renal failure or evidence of co-existing severe liver disease. No patient should be denied any imaging investigation that is critical to clinical management, which takes precedent over any other cautionary measures. Informed consent should be obtained by the radiologist if intravenous gadolinium is to be given to high risk patients.
Key point: Gadolinium should only be given to a patient who is on dialysis or has a GFR < 30 if the imaging study is considered critical to clinical management AND informed consent has been obtained by a radiologist.
Role of dialysis after gadolinium administration in patients with renal impairment
Dialysis does not protect patients from developing NSF1. Studies have shown that the serum concentration of gadolinium is significantly decreased after hemodialysis, however, there is no information regarding residual tissue amounts2. Theoretically, the sooner the dialysis session is performed the less amount of contrast agent is deposited in the tissues. Therefore, all patients already receiving dialysis treatment should be scheduled for dialysis as soon as practical following the gadolinium-enhanced MRI and preferably within 24 hours. This should be arranged by the requesting physician in consultation with the patient’s outpatient nephrologist and dialysis unit. Routine MRI studies should be scheduled in the morning and dialysis scheduled in the afternoon following the study; radiology scheduling staff will give morning slot priority to dialysis patients. Administration of hemodialysis promptly after gadolinium may require altering the patient’s regular outpatient dialysis schedule and advance communication several days in advance with the nephrologist and dialysis unit. There is general consensus that a patient with chronic kidney disease who is not already dialysis dependent should not be started on dialysis after administration of gadolinium for precautionary purposes only, since there is no data to support the benefits of this intervention.
Key point: Dialysis should preferably be performed within 24 hours of gadolinium administration to patients already on dialysis. The institution of dialysis is not required in patients with severe renal impairment who are not already on dialysis after gadolinium administration.
Creatinine testing prior to gadolinium administration
Laboratory results should be checked for the most recent serum creatinine on ALL patients (by the technologist performing the study). For patients with the following risk factors, serum creatinine with calculation of eGFR should be performed within 6 weeks of the MRI study:
Age over 60 years
History of “kidney disease” as an adult, including tumor and transplant
Family history of kidney failure or disease
Diabetes treated with insulin or other prescribed medications
Hypertension (high blood pressure) requiring medication
Multiple myeloma
Solid organ transplant
History of severe hepatic disease/liver transplant/pending liver transplant. For patients in this category only, it is recommended that the patient's GFR assessment be nearly contemporaneous with the MR examination for which the gadolinium is to be administered.
Routine creatinine testing prior to contrast administration is NOT necessary in all patients1,2. With the exception of age and hypertension (see below), the indications for creatinine testing in the above guidelines are those suggested by the ACR1. However, these recommendations should be considered in the light of several confounding factors:
In a study of 2034 outpatients who all had routine creatinine testing prior to outpatient CT, 66 patients had a creatinine of 2.0 or above2. All but 2 of the 66 had one or more of 8 risk factors that were chosen based on published literature (history of renal insufficiency or renal disease, diabetes mellitus, advanced age, male gender, nephrotoxic-drug use, chemotherapy, HIV/AIDS, solitary kidney). The two cases that would have been “missed” by a policy of selective creatinine testing had a creatinine of 2.0 and 2.2. Two particularly notable findings in this study were that age alone was not an important risk factor, and that both insulin-dependent diabetes mellitus and non-insulin-dependent diabetes were important risk factors.
The use of age as a risk factor and the choice of threshold are both controversial, with conflicting data in the literature. Community based studies of serum creatinine suggest age, hypertension, and diabetes are important predictors of creatinine elevation3-5. In addition, many centers use age (with variable thresholds) to determine the need for creatinine testing and this practice is also engrained in the department culture at UCSF.
Standard practice is variable and often based on little to no evidence15. For example, there is little data on whether in-patients are substantively different to outpatients.
Arguably, the list of medications should be expanded to include chemotherapy, since many of these drugs are nephrotoxic16.
In general, these guidelines are simply guidelines, and strict adherence in every case may not be in the patient's best interest. Physician discretion and judgment are paramount, and commonsense should be applied to individual patient's circumstances. Conversely, it may be prudent to check creatinine in a sick debilitated patient even if they do not have any of the specific factors listed above.
Key point: Routine creatinine testing prior to contrast administration is NOT necessary in all patients; the major indications are age over 60, history of preexistent renal insufficiency, diabetes mellitus, or hypertension.
