Editing Kidney Cancer: Diagnosis and Evaluation (section)

===== IV contrast =====

*'''<span style="color:#ff0000">Contraindications (2):'''
*# '''<span style="color:#ff0000">Severe allergy'''
*# '''<span style="color:#ff0000">Severe chronic kidney disease'''
** '''<span style="color:#ff0000">Patients with GFR <45 ml/min/1.73m2 should receive contrast with caution</span>'''
*** '''Patients with acute kidney injury or GFR < 30 mL/min/1.73m2 who are not undergoing renal replacement therapy should receive intravenous normal saline prophylaxis prior to receiving iodinated contrast media[https://pubmed.ncbi.nlm.nih.gov/34115547/ §].'''
*** '''Patients with GFR 30-44 mL/min/1.73m2 may be considered for intravenous fluid prophylaxis per individual physician discretion based on the patient’s risk factor for renal injury[https://pubmed.ncbi.nlm.nih.gov/34115547/ §].'''
**** '''MRI with second generation gadolinium-based intravenous contrast is now a safer option in many patients with severe CKD'''
**'''In patients who cannot receive intravenous contrast, MRI, non-contrast CT, and US (with Doppler) can be used to characterize renal masses''' 
*'''<span style="color:#ff0000">Contrast-induced nephropathy'''
** '''Due to intrarenal vasoconstriction and tubular necrosis'''
** '''<span style="color:#ff0000">Risk factors'''
**# '''<span style="color:#ff0000">Diabetes mellitus'''
**# '''<span style="color:#ff0000">Advanced age'''
**# '''<span style="color:#ff0000">Congestive heart failure'''
**# '''<span style="color:#ff0000">Hypertension'''
**# '''<span style="color:#ff0000">Dehydration'''
**# '''<span style="color:#ff0000">Diuretic use'''
**# '''<span style="color:#ff0000">Low hematocrit'''
**# '''<span style="color:#ff0000">Ventricular ejection fraction < 40%'''
**# '''<span style="color:#ff0000">Concomitant exposure to chemotherapy, aminoglycoside or nonsteroidal anti-inflammatory agents'''
**# '''<span style="color:#ff0000">Hyperuricemia'''
**# '''Diseases that affect renal hemodynamics, such as end-stage liver disease and nephrotic syndrome'''
**# '''Patients with a diagnosis of a paraproteinemia syndrome/disease (e.g., multiple myeloma), history of a kidney transplant, renal tumor, renal surgery, or single kidney may also be at higher risk'''
*** '''The patients at highest risk for developing CIN are those with both diabetes and pre-existing renal insufficiency.'''
** '''<span style="color:#ff0000">Metformin'''
*** '''Patients with type 2 diabetes mellitus receiving metformin may have an accumulation of the drug after administering intravascular radiologic contrast medium (IRCM), resulting in biguanide lactic acidosis'''
*** '''Biguanide lactic acidosis'''
**** Symptoms of include vomiting, diarrhea, and somnolence
**** Fatal in ≈50% of cases
**** '''Rare in patients with normal renal function (no defined threshold but some studies suggest <60).'''
***** '''In patients with normal renal function and no known comorbidities there is no need to discontinue metformin before IRCM use, nor is there a need to check creatinine following the imaging study.'''
***** '''<span style="color:#ff0000">In patients with renal insufficiency metformin should be discontinued the day of the study and withheld for 48 hours. Post-procedure creatinine should be measured at 48 hours and metformin started once kidney function is normal.'''
**** It is not necessary to discontinue metformin before gadolinium-enhanced MRI studies when the amount of gadolinium administered is in the usual dosage range of 0.1 to 0.3 mmol per kilogram of body weight.
*** Prevention of CIN is of great concern and has been a subject of many different studies. Hydration is the major preventative action against CIN. Periprocedural IV hydration with 0.9% saline at 100 mL/hr 12 hours before to 12 hours after has been shown to decrease the incidence of CIN after IV contrast use