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Acute Kidney Injury. Pamela Pride, MD, FHM Cathryn Caton, MD, MS June 5, 2012 MUSC. Objectives. Define Acute Kidney Injury (AKI) Define the significance of AKI in a hospitalized patient Differentiate pre/intra/post renal injury
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Acute Kidney Injury Pamela Pride, MD, FHM Cathryn Caton, MD, MS June 5, 2012 MUSC
Objectives • Define Acute Kidney Injury (AKI) • Define the significance of AKI in a hospitalized patient • Differentiate pre/intra/post renal injury • Utilize history, physical exam and appropriate diagnostic tests to determine etiology of AKI
Acute Kidney Injury – What is it? • An abrupt or rapid decline in renal filtration function • Marked by • rise in serum creatinine • azotemia • Patients may be • Oliguric • Non - oliguric
Importance of AKI OR 1.7; 95% CI, 1.2 to 2.6 Green bars unadjusted Blue Bars age and gender adjusted Gray bars are multivariable adjusted
Common Causes of AKI OUTPATIENT INPATIENT • ACE-I when vomiting • ACE-I + NSAID • BPH • Stones • ATN • Sepsis • Drugs • Contrast • Rhabdomyolysis
Approach to a Patient with AKI • Think three broad categories • Pre-renal • Intrinsic renal • Post-renal
Evaluation of AKI • HPI • Past Medical History – • ?CKD • ?DM • ?Proteinuria • ?HTN • Family History • Social History – • IVDA • Hepatitis • HIV risks • Medications – review all medications • Physical Exam
Physical Exam • Pre-Renal • Orthostatic hypotension • Tachycardia • Decreased skin turgor • Signs of heart failure • Post-renal • Palpable bladder
Physical Exam • Intrinsic renal • ATN – volume overload • Glomerulonephritis – variable • Vasculitis – purpura • Atheroembolic disease – livedoreticularis, blue toes • Interstitial nephritis – rash, fever, +/- eos
Laboratory Data • BMP • CBC • UA • Urine sediment – look for muddy brown casts • FeNa • Renal Ultrasound or Computed tomography
Interpreting FeNa • Non-pre-renal with low FeNa • Contrast • Rhabdo • Early sepsis • Obstruction • Acute glomerulonephritis • Pre-renal with high FeNa • Diuretic use • Pre-existing CKD
Pre-Renal • Hypoperfusion • Hypovolemia • Decreased cardiac output • Decreased effective circulatory volume • CHF • Cirrhosis • Impaired renal hemodynamics • NSAIDs • ACE • ARB
Intrinsic AKI • Essentially ruled out pre-renal, post-renal • No good reason for ATN • Check complement levels – C3, C4 • ANCA, antiGBM • ANA • LDH, haptoglobin – hemolysis, thrombotic microangiopathy
Post-Renal AKI • Obstruction • BPH • Stone
Interpreting urinary sediment Granular cast RBC cast
Interpreting urinary sediment Tubular Epithelial Cells WBC vs Epithelial Cell
Interpreting urinary sediment Oval Fat Bodies WBC Cast
References • Chertow GM, Burdick E, Honour M, et. Al. Acute Kidney Injury, mortality, length of stay, and costs in hospitalized patients. J Am Soc Nephrol, 16: 3365-70, 2005. • Wald R, Quinn RR, Luo J et. al. Chronic dialysis and death among survivors of acute kidney injury requiring dialysis. JAMA, 302: 1179-85, 2009. • Blantz RC. Pathophysiology of pre-renal azotemia. Kidney Int, 53: 512-23, 1998. • Friedrich JO, Adhikari N, Herridge MS, et. al. Meta-analysis: low dose dopamine increases urine output but does not prevent renal dysfunction or death. Ann Intern Med, 142: 510-24, 2005 • Steiner RW: Interpreting the fractional excretion of sodium. Am J Med, 77: 699-702, 1984