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Renal Function

St. Luke’s-West Hospital uses a creatinine method traceable to IDMS
IODINATED CONTRAST

RENAL INSUFFICIENCY SCREEN Cr > 1.5
check eGFR and trend for true renal function


CONTRAST INDUCED NEPHROTOXICITY IN RENAL INSUFFICIENCY

IVF Hydration (100 cc/hr 12 hours before and 12 hours after) if patient can tolerate
Controversial  600 mg -1200 mg acetylcysteine  PO x 4 (2 before and  after) ~ also smells like rotten eggs.



The efficacy of N-acetylcysteine (Mucomyst), an antioxidant, to reduce the incidence of CIN is controversial .There is evidence that it reduces serum creatinine in normal volunteers without changing cystatin C (said to be a better marker of GFR than serum creatinine) . This raises the possibility that N-acetylcysteine might be simply lowering serum creatinine, so patients do not meet the laboratory criteria for CIN, but not preventing the renal damage.  Oral acetylcysteine, 600 mg twice daily on the day before and on the day of administration of iodinated contrast media, is simple, inexpensive, and has few contraindications, but it smells like rotten eggs.  Alternatively, an IV regimen beginning 30 minutes prior to contrast media administration may be considered (150 mg/kg in 200 ml of D5W over 30 minutes, followed by 50 mg/kg in 500 ml of D5W over 4 hours) . However, IV administration may have a higher rate of adverse effects than oral administration

Risk OF CIN increases with increasing creatinine
    Cr < 1.5:  risk approx. 0.6%
    Cr 1.5-4.5:  risk approx. 9.2%
    Cr >4.5:  risk approx. 39%

Renal dysfunction resolves in 75-90% of cases.  Dialysis needed <25%.


References
Tepel M, Zidek W. Acetylcysteine and contrast media nephropathy. Curr Opin Nephrol Hypertens.  Sep 2002; 11(5):503-6).
Giancarlo Marenzi et al. N-Acetylcysteine and Contrast-Induced Nephropathy in Primary Angioplasty.  N Engl J Med 2006; 354:2773-2782 June 29,2006.



MULTIPLE MYELOMA
 
Patients with multiple myeloma may receive iodinated IV contrast if they are adequately hydrated and are not significantly hypercalcemic.  Recent creatinine and calcium levels should therefore be reviewed prior to administering contrast.  In addition, the ACR suggests oral or IV hydration for 6-12 hours prior to receiving contrast, and also for at least 6-12 hours after.
               
Multiple myeloma was once thought to be a significant risk factor for developing contrast nephropathy.  However, the incidence of contrast nephropathy in myeloma patients is only 0.6-1.25% compared to the risk of 0.15% in the general public.  Furthermore, the risk has subsequently been shown not to be related to myeloma itself, but rather to the presence of associated dehydration, hypercalcemia, infection and Bence Jones proteinuria.  Hypercalcemic patients experience emesis and nephrogenic diabetes insipidus, both causing dehydration and cast formation, and these patients also suffer from direct toxic effects of elevated calcium (nephrocalcinosis).  Infection causes dehydration and may involve the use of nephrotoxic antibiotics.  Bence Jones proteinuria leads to precipitation of protein casts in dehydrated patients causing acute renal failure.  Bence Jones proteins can also have a more chronic toxic effect on tubular cells.  Older contrast agents were noted to form precipitates with Bence Jones protein in vivo, but this is not seen with modern agents.  These conditions are all risk factors for acute renal failure in multiple myeloma patients that exist in the absence of contrast media.

McCarthy CS, Becker JA. Multiple myeloma and contrast media. Radiology 1992; 183:519-521


RENAL TRANSPLANT OR SINGLE KIDNEY?
 
Patients with a renal transplant or a single kidney that have normal renal function (normal creatinine level) can receive intravenous contrast at the normal dose.
 
A study by Moreau et al. showed no increased incidence of contrast nephropathy in renal transplantation patients with normal renal function.  Another study showed an incidence of contrast nephropathy of 21.2% in transplantation patients with an unenhanced average serum creatinine value of 2.3 mg/dL.

Gadolinium administration in single kidney is not officially contraindicated, but our department usually prefers not to do so.


Reference:
Elicker BM, Cypel YS, Weinreb JC. IV contrast administration for CT: A survey of practices for the screening and prevention of contrast nephropathy. AJR 2006; 186:1651-1658 

    


 
SICKLE CELL DISEASE
 
Patients with sickle cell disease that have normal renal function (normal creatinine level) can receive intravenous contrast at the normal dose.  Oral hydration should be encouraged before and after receiving intravenous contrast.
 
According to the ACR, although it has been suggested in the past “that sickle cell trait or disease increases the risk to patients,” “in neither case is there evidence of significant clinical risk.”  Previously-described sickle cell crisis exacerbations induced by intravenous contrast were seen more commonly with the use of older, high osmolar contrast media (HOCM).


References:
American College of Radiology Manual on Contrast Media, Version 6, 2008
Fishman EK et al. Everything you wanted to know about contrast but were afraid to ask. Johns Hopkins Hospital. 2008 RSNA contrast exhibit.




MORE ON CIN & BORDERLINE RENAL FUNCTION


There is no standard definition for reporting contrast media induced nephrotoxicity (CIN).  Definitions used have included percent change in the baseline serum creatinine (e .g ., a 20% to 50% rise in serum creatinine) and absolute elevation from baseline (increase of 0 .5 to 2 .0 mg/dl) within 48 to 72 hours of contrast administration.  In a typical contrast induced nephropathy, serum creatinine usually begins to rise within the first 24 hours following IV contrast media administration, peaks within 96 hours (4 days), and usually returns to baseline within 7 to 10 days.

Indications for pre-contrast creatinine measurement/calculation of eGFR
    History of “kidney disease” as an adult, including tumor and transplant
    Family history of kidney failure
    Diabetes treated with insulin or other medications
    Paraproteinemia syndromes or diseases (e.g.,multiple myeloma)   
    Collagen vascular disease (e.g., scleroderma,systemic lupus erythematosa)
    Prior renal surgery   
    Metformin or metformin-containing drug combinations
    Chronic or high dose use of non-steroidal anti-inflammatory drugs
    Regular use of nephrotoxic medications, such as aminoglycosides
    ALL INPATIENTS

When creatinine clearance is less than 60 ml/ min (in a normal young adult equivalent to a serum creatinine of 1 .5 mg/dl) the term “renal insufficiency” has been used, and when creatinine clearance is less than 30 ml/min the term “renal failure” is often used.

The threshold values at which different clinical actions should be taken (e .g ., active intravenous hydration, avoidance of contrast material administration) are neither proven nor generally agreed upon for either serum creatinine measurement or calculated creatinine clearance.  In our institution, patients with renal failure undergoing dialysis may receive intravenous contrast with dialysis scheduled to accommodate the volume load of contrast. 

The patients at highest risk for developing contrast media induced acute renal failure are those with both diabetes and pre-existing renal insufficiency (i.e. creatinine clearance less than 60 ml/min).  One additional risk factor is thought to be the use of multiple contrast examinations within a short time interval of less than 24 hours, the time it takes the kidneys to excrete a dose of contrast media.  

The major preventive action against CIN is to ensure adequate hydration . If the patient cannot be hydrated orally, one could consider IV infusion of 0 .9% saline at 100 ml/hr in adults, beginning 6 to 12 hours before and continuing 4 to 12 hours after the administration of contrast media.





References
Parfrey PS, Griffiths SM, Barrett BJ, et al. Contrast material- induced renal failure in patients with diabetes mellitus, renal insufficiency, or both. A prospective controlled study. N Engl J Med 1989; 320:143–149 .
Schwab SJ, Hlatky MA, Pieper KS, et al . Contrast nephrotoxicity: a randomized controlled trial of a nonionic and an ionicradiographic contrast agent . N Engl J Med 1989; 320:149–153.
Tippins RB, Torres WE, Baumgartner BR, Baumgarten DA . Are screening serum creatinine levels necessary prior to outpatient CT examinations? Radiology 2000; 216:481–484.
Elicker BM, Cypel YS, Weinreb JC . IV contrast administra- tion for CT: a survey of practices for the screening and pre- vention of contrast nephropathy.  AJR Am J Roentgenol 2006; 186:1651–1658.
Poletti PA, Saudan P, Platon A, et al . I .v . N-acetylcysteine and emergency CT: use of serum creatinine and cystatin C as markers of radiocontrast nephrotoxicity . AJR Am J Roentgenol 2007; 189:687–692.





DIALYSIS PATIENTS
If the patient is on chronic dialysis, it is ok to administer iodinated contrast media.  We typically recommend that the patient receive dialysis within 24 hours.

Patients with renal insufficiency who require only intermittent or occasional dialysis are at substantial risk for contrast media-induced nephrotoxicity with further permanent worsening of their renal function. Alternative imaging studies that do not require contrast media should be considered.
GADOLINIUM

RENAL INSUFFICENCY  eGFR<45
Above 45, routine, Magnevist, dosed approximately 2 cc/kg~1 cc/lb, max 20cc



NSF
Nephrogenic System Fibrosis (NSF) can develop in patients with severe to end-stage kidney disease after administration of a gadolinium based contrast agents (GBCA).  This complication can develop up to 3 months or longer after contrast administration.  The FDA recommends the use of alternative imaging methods for patients with severe to end-stage kidney disease when gadolinium-enhanced MRI or MRA studies are requested.   Note that GBCAs have been occasionally used in place of iodinated agents in the past for CT or catheter angiography in patients with renal failure or severe allergies; the same policy applies to these patients.

Screening for Kidney Function
Every MRI patient or their guardian must fill out an MRI safety questionnaire. 
The form is reviewed and signed by the technologist.

Outpatient exams: If patient has any of the following, it is recommended that the eGFR be calculated and the lab values be nearly contemporaneous with the MR examination
            Age >60
            History of Hypertension
            History of Diabetes
            Renal disease (including solitary kidney, renal transplant, renal tumor)
            History of severe hepatic disease/transplant/pending transplant                    
Inpatient exams: eGFR calculation is required for all inpatient exams

The injecting staff will verbally confirm the answers from safety form to:
Are you on dialysis?
Do you have end stage renal disease?
Do you have kidney failure?        

Exemptions: Approval and Documentation of Medical Necessity in Patients with Renal Impairment

The clinician ordering an exam with GBCA injection for a patient with significant kidney disease must fully assess the risk/benefit ratio in consultation with a radiologist. This will require direct physician-to-physician communication.
Patients with acute or chronic kidney disease and an eGFR less than 30 ml/min/1.73 m2 are at risk for NSF. Risks of gadolinium injection must be carefully weighed against the benefits. Therefore, a nephrology consultation and approval for GBCA injection must be obtained prior to injection.
Patients already on hemodialysis or peritoneal dialysis have, by definition, GFR less than 30 ml/min/1.73 m2. These individuals fall into the category of patients addressed in #2 above. 
The exam can be scheduled only with an approval by a radiologist who has consulted with, or has knowledge of the consultation with, the ordering provider and / or the nephrology consultant.
The ordering clinician must clearly document the need for GBCA injection and lack of alternates in the patient’s medical record.
If nephrology clearance cannot be obtained at the time of the scan, or if the renal function cannot be determined in a patient at risk for kidney disease, and the information needed by the injection is not life-sustaining or integral to the particular exam, the MRI should be performed without contrast. The need for contrast administration can be assessed later. Approval by a radiologist must be obtained by the technologist prior to performing the exam without contrast.
 Informed consent for injection must be obtained by the radiologist.
The contrast dose should be reduced as much as possible. Only a single dose may be given.
The volume of contrast injected and the gadolinium agent utilized must be documented in the patient’s chart by the injecting radiologist, and should be dictated into the radiology report.
 Hemodialysis after contrast injection is recommended for those patients with eGFR<30, & scheduled by the nephrology service. Note that hemodialysis has not been clinically proven to eliminate the risk for subsequent NSF. Peritoneal dialysis has no role in elimination of gadolinium.