acute kidney injury (acute renal failure )

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Acute Kidney Injury (Acute Renal Failure ). Shokoufeh Savaj MD Associate Professor of Medicine Firouzgar hospital Iran University of Medical Sciences. Definition. Rapid decline in glomerular filtration rate (GFR) over hours to days. Diagnostic criteria for ARF. - PowerPoint PPT Presentation

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Acute Renal Failure

Shokoufeh Savaj MDAssociate Professor of MedicineFirouzgar hospitalIran University of Medical Sciences

Acute Kidney Injury (Acute Renal Failure ) DefinitionRapid decline in glomerular filtration rate (GFR) over hours to daysDiagnostic criteria for ARFAbrupt (within 48 hours) absolute increase in the serum creatinine concentration of 0.3 mg/dL from baselineA percentage increase in the serum creatinine concentration of 50 percent Oliguria of less than 0.5 mL/kg per hour for more than six hoursClassifications for Acute Renal Failure

ClassificationPrerenal (55%)Renal(40%)Post renal (5%)Pathogenesis of prerenal AzotemiaFall in mean systemic arterial pressure,Reduced stretch by arterial (e.g., carotid sinus) and cardiac baroreceptorsNeurohormonal responses t( activation sympathetic nervous system ,RAS system and vasopressin release.Vasoconstrictrion in musculocutaneous and splanchnic circulations Preserved cardiac and cerebral perfusion pressureDecrease salt loss and stimulation of thirst and salt appetite

Local myogenic reflex (autoregulation). Angiotensin II increases biosynthesis of vasodilator prostaglandins (e.g., prostaglandin E2 and prostacyclinAfferent arteriolar vasodilationConstriction of efferent arterioles. Increased filtration fraction Maintenance of intraglomerular pressure and GFR Severe hypoperfusion, GFR falls, leading to prerenal ARF.

Prerenal ARF Hypovolemia A. Increased extracellular fluid lossesB. Gastrointestinal fluid lossC. Renal fluid lossD. Extravascular sequestrationE. Decreased intakeAltered renal hemodynamics resulting in hypoperfusion A. Low cardiac output stateB. Systemic vasodilationC. Renal vasoconstrictionD. Impairment of renal autoregulatory responsesE. Hepatorenal syndrome

Glomerular and microcirculation Interstitial nephritisAcute tubular necrosisDiseases of larger renal vessels Intrinsic ARFIntrinsic ARFRenovascular obstruction A. Renal artery obstructionB. Renal vein obstructionDiseases of the glomeruli or vasculature A. Glomerulonephritis or vasculitis B. thrombotic microangiopathy, malignant hypertension, collagen vascular diseases (systemic lupus erythematosus, scleroderma), disseminated intravascular coagulation, preeclampsiaRenal Vein thrombosis

Renal artery stenosis

Post Streptococcal Glomerulonephritis

Acute tubular necrosisA. IschemiaB. Infection, with or without sepsis syndrome C. Toxins: 1. Exogenous: 2. Endogenous: rhabdomyolysis, hemolysis

Decrease blood flow and oxygen delivery Increase oxygen consumption and direct cellular toxicityRenal medullary hypoxia

Interstitial nephritis A. AllergicB. InfectionC. Infiltrations D. Inflammatory, nonvascular: Sjgren's syndrome, tubulointerstitial nephritis with uveitis

Intrinsic ARF

Intratubular obstruction A. EndogenousB. Exogenous

Intrinsic ARF

39

Post renal

Ureterovesical junction ObstructionLaboratory studies in prerenal acute renal failure (ARF) and acute tubular necrosis (ATN)PrerenalATN

Urine Sodium (meq/L)30

Urine Osmolarity

> 500 mosmol 20 < 20Fractional Excretion of Sodium < 1%> 2%Fractional Excretion of Sodium UNaxPCrFENa %= x100 PNaxUCrDiagnosis of ARFEtiologyEpidemiologyClinical featuresSerum studiesUrine studiesPrerenal ARFMost commonHistory of poor fluid intake ,Worsening heart failureTreatment with ACE/ARB/NSAID Clincal signs of volume depletionHigh BUN /Cr > 20 is suggestiveHyaline castsFENa < 1%Urine Na < 10 mmol/L Urine SG > 1018Diagnosis of ARFEtiologyEpidemiologyClinical featuresSerum studiesUrine studiesIschemia Severe hemorrhage or hypotensionMuddy browun tubular or epithelial cast castsFENa > 1%Urine Na >20 mmol/L Urine SG 60yrs age, contitutional symptoms

Anemia,monoclonal spikeProteinuria spike on urine electrophoresisEthylene glycolHistory of alcohol abuse,altered mental stateHigh anion gap acidosis,with osmolal gap,positive toxicityOxalate crystals47EtiologyEpidemiologyClinical featuresSerum studiesUrine studiesAllergic interstitial nephritisRecent medication exposureFever ,rash,arthralgiaEosinophiliaWhite cell casts ,eosinophiluria Acute bilateral pyelonephritisFever, flank pain and tendernessPositive blood cultures leukocytes,proteinuria,positive urine culturePostrenal ARFHistory of renal stones or prostatic diseasePalpable bladder,flank or abdominal painUsually normal .hematuria if due to stones48Novel biomarkers of acute kidney injury*Low molecular weight proteins: (Alpha1-Microglobulin (alpha1-M), beta2-Microglobulin (beta2-M), retinol binding protein (RBP), adenosine deaminase binding protein (ABP), and urinary cystatin C*Tubular enzymes :Urinary tubular enzymes consist of proximal renal tubular epithelial antigen (HRTE-1), alpha-Glutathione S-transferase (alpha-GST), pi-Glutathione S-transferase (pi-GST), gamma-Glutamyltranspeptidase (gamma-GT), Alanine aminopeptidase (AAP), Lactate dehydrogenase (LDH), N-acetyl-beta-glucosaminidase (NAG), and Alkaline phosphatase (ALP). Kidney injury molecule 1 (KIM1)Transmembrane protein in proximal tubular cellsPhagocytic properties of tubular cellDD prerenal from ATN

Neutrophil gelatinase associated lipocalin (NGAL)Protein in granules with tissueProtective effect of in proximalIncreases 2 hours after ischemic injury Novel biomarkers of acute kidney injuryClassification/staging system for acute kidney injury*