Acute Renal FailureAcute Renal FailureOrOr

The Kidney Is Your FriendThe Kidney Is Your Friend

Katie Murphy MDKatie Murphy MD

September 2007September 2007

Katie’s Approach to Medical Katie’s Approach to Medical TopicsTopics

• For any topic, I ask the following For any topic, I ask the following questions:questions:

•What Is It? (Definitions, Classifications)What Is It? (Definitions, Classifications)

•Why Do I Care? (Prevalence, Morbidity, Why Do I Care? (Prevalence, Morbidity, Mortality)Mortality)

•What Do I Need to Do? (Workup)What Do I Need to Do? (Workup)

What Is Acute Renal Failure What Is Acute Renal Failure ??

• There is no universally accepted There is no universally accepted definition of acute renal failure (ARF).definition of acute renal failure (ARF).

What Is Acute Renal Failure What Is Acute Renal Failure ??• There is no universally accepted definition There is no universally accepted definition

of acute renal failure (ARF).of acute renal failure (ARF).

• Commonly used definition is > or = to Commonly used definition is > or = to 0.5mg/dl increase in serum creatinine in 2 0.5mg/dl increase in serum creatinine in 2 weeks or less if the baseline creatinine is weeks or less if the baseline creatinine is less than 2.5mg/dl.less than 2.5mg/dl.

• If baseline creatinine is greater than If baseline creatinine is greater than 2.5mg/dl, ARF is defined as a greater than 2.5mg/dl, ARF is defined as a greater than 20% increase.20% increase.

What Is Acute Renal What Is Acute Renal Failure?Failure?

• Oliguric Renal FailureOliguric Renal Failure

What Is Acute Renal What Is Acute Renal Failure?Failure?

• Oliguric Renal FailureOliguric Renal Failure

Less than 500 ml urine output/day in Less than 500 ml urine output/day in adultsadults

What Is Acute Renal What Is Acute Renal Failure?Failure?

• Oliguric Renal FailureOliguric Renal Failure

Less than 500 ml urine output/day in Less than 500 ml urine output/day in adultsadults

Derived from the fact that a healthy kidney, if Derived from the fact that a healthy kidney, if maximally concentrating the urine, will have to maximally concentrating the urine, will have to excrete 500 ml urine per day to get rid of the excrete 500 ml urine per day to get rid of the daily osmotic load from dietary intake and daily osmotic load from dietary intake and

metabolic byproductsmetabolic byproducts..

What Is Acute Renal What Is Acute Renal Failure?Failure?• Oliguric Renal FailureOliguric Renal Failure

Less than 500 ml urine output/day in Less than 500 ml urine output/day in adultsadults

Derived from the fact that a healthy kidney, if Derived from the fact that a healthy kidney, if maximally concentrating the urine, will have to maximally concentrating the urine, will have to excrete 500 ml urine per day to get rid of the daily excrete 500 ml urine per day to get rid of the daily osmotic load from dietary intake and metabolic osmotic load from dietary intake and metabolic

byproductsbyproducts..

• Anuric Renal FailureAnuric Renal Failure

What Is Acute Renal What Is Acute Renal Failure?Failure?• Oliguric Renal FailureOliguric Renal Failure

Less than 500 ml urine output/day in Less than 500 ml urine output/day in adultsadults

Derived from the fact that a healthy kidney, if Derived from the fact that a healthy kidney, if maximally concentrating the urine, will have to excrete maximally concentrating the urine, will have to excrete 500 ml urine per day to get rid of the daily osmotic 500 ml urine per day to get rid of the daily osmotic

load from dietary intake and metabolic byproductsload from dietary intake and metabolic byproducts..

• Anuric Renal FailureAnuric Renal Failure

Less than 100 ml/day urine outputLess than 100 ml/day urine output

What Is Acute Renal What Is Acute Renal Failure?Failure?• Oliguric Renal FailureOliguric Renal Failure Less than 500 ml urine output/day in adultsLess than 500 ml urine output/day in adults Derived from the fact that a healthy kidney, if maximallyDerived from the fact that a healthy kidney, if maximally concentrating the urine, will have to excrete 500 ml urineconcentrating the urine, will have to excrete 500 ml urine per day to get rid of the daily osmotic load from dietaryper day to get rid of the daily osmotic load from dietary

intake and metabolic byproductsintake and metabolic byproducts..• Anuric Renal FailureAnuric Renal Failure Less than 100 ml/day urine outputLess than 100 ml/day urine output• Non-Oliguric Renal FailureNon-Oliguric Renal Failure

Chronic Kidney DiseaseChronic Kidney Disease

• The new nomenclature for renal disease:The new nomenclature for renal disease:– Stage 1 CKD: kidney damage but normal GFR Stage 1 CKD: kidney damage but normal GFR

(>90ml/min)(>90ml/min)– Stage 2 CKD: mild kidney damage (GFR Stage 2 CKD: mild kidney damage (GFR

60-89ml/min)60-89ml/min)– Stage 3 CKD: moderate kidney damage (GFR 30-Stage 3 CKD: moderate kidney damage (GFR 30-

59ml/min)59ml/min)– Stage 4 CKD: severe kidney damage (GFR 15-Stage 4 CKD: severe kidney damage (GFR 15-

29ml/min)29ml/min)– Stage 5 CKD: kidney failure (GFR < 15ml/min or Stage 5 CKD: kidney failure (GFR < 15ml/min or

ESRD on renal replacement therapy)ESRD on renal replacement therapy)

Why Do We Care ?Why Do We Care ?

• ARF occurs in 5% of hospitalized patients.ARF occurs in 5% of hospitalized patients.

• ARF has been found to be related to a ARF has been found to be related to a 20% mortality rate (often infectious or 20% mortality rate (often infectious or cardiorespiratory)cardiorespiratory)

• When serum creatinine increases by When serum creatinine increases by >3.0mg/dl, mortality approaches 40-50% >3.0mg/dl, mortality approaches 40-50% and thus prompt diagnosis and institution and thus prompt diagnosis and institution of appropriate treatment is crucial.of appropriate treatment is crucial.

Etiologies of Acute Renal Etiologies of Acute Renal FailureFailure

• Pre-Renal Pre-Renal

• Post-Renal Post-Renal

• Intrinsic or Intra-RenalIntrinsic or Intra-Renal

Pre-Renal Acute Renal Pre-Renal Acute Renal FailureFailure• Accounts for 60-70% of ARF.Accounts for 60-70% of ARF.

• Etiologies:Etiologies:– True Volume Depletion (blood loss, dehydration)True Volume Depletion (blood loss, dehydration)– Effective Circulating Volume Depletion (CHF, Effective Circulating Volume Depletion (CHF,

sepsis)sepsis)– Hypotension (sepsis, meds, cardiogenic shock)Hypotension (sepsis, meds, cardiogenic shock)– ACE-InhibitorsACE-Inhibitors– NSAIDSNSAIDS– Hepatorenal Syndrome Hepatorenal Syndrome

Post-Renal Acute Renal Post-Renal Acute Renal FailureFailure• Accounts for 5-10% of ARF.Accounts for 5-10% of ARF.

• Remember anatomy and have a Remember anatomy and have a systematic approach.systematic approach.

• Etiologies include:Etiologies include:– Ureteral: Tumors, stones, clot and Ureteral: Tumors, stones, clot and

lymphadenopathylymphadenopathy– Bladder: Tumors, stones, neurogenic, drugsBladder: Tumors, stones, neurogenic, drugs– Prostate: Hypertrophy, tumorsProstate: Hypertrophy, tumors– Urethral: Strictures, tumorsUrethral: Strictures, tumors

Intrinsic Renal ARFIntrinsic Renal ARF

•Accounts for 25-40% of Accounts for 25-40% of

ARF.ARF.

•Again, remember theAgain, remember the

component anatomy component anatomy

of the kidneyof the kidney..

Intrinsic Renal ARFIntrinsic Renal ARF• Accounts for 25-40% of ARF.Accounts for 25-40% of ARF.• Again, remember the component anatomy of the Again, remember the component anatomy of the

kidneykidney..• VesselsVessels: : Vasculitis, EmboliVasculitis, Emboli

• GlomerulusGlomerulus: : Nephrotic syndromes, Nephritic Nephrotic syndromes, Nephritic SyndromesSyndromes

• TubulesTubules: : Acute Tubular Necrosis, Rhabdomyolysis, Acute Tubular Necrosis, Rhabdomyolysis, Contrast NephropathyContrast Nephropathy

• Interstitium(peri-tubular and peri-arteriolar Interstitium(peri-tubular and peri-arteriolar tissue) tissue) : : Acute Interstitial Nephritis, Severe Acute Interstitial Nephritis, Severe PyelonephritisPyelonephritis..

What Do We Need to Do ?What Do We Need to Do ?

• First, you need to suspect acute renal First, you need to suspect acute renal failure.failure.

• Presentation of ARF:Presentation of ARF:•Most patients are asymptomatic, but symptoms includeMost patients are asymptomatic, but symptoms include

MalaiseMalaise HypertensionHypertension

HematuriaHematuria EncephalopathyEncephalopathy

Flank PainFlank Pain PruritisPruritis

DyspneaDyspnea Bleeding from plateletBleeding from platelet

dysfunctiondysfunction

EdemaEdema Oliguria/AnuriaOliguria/Anuria

What Do We Need to Do What Do We Need to Do Part 2Part 2• Now, we need to look for risk factors, Now, we need to look for risk factors,

symptoms and signssymptoms and signs

• History: History: – Drugs: Anticholinergics, IV Contrast, Drugs: Anticholinergics, IV Contrast,

Aminoglycosides, Amphotericin.Aminoglycosides, Amphotericin.•Classic AIN Medications:Classic AIN Medications:

– PenicillinsPenicillins– CephalosporinsCephalosporins– Sulfa drugsSulfa drugs– NSAIDSNSAIDS– RifampinRifampin

History ContinuedHistory Continued

• Causes of Volume DepletionCauses of Volume Depletion

• Autoimmune DiseaseAutoimmune Disease

• Previous History of ARFPrevious History of ARF

Physical ExamPhysical Exam

• Volume Status: Volume Status: – TachycardiaTachycardia– Mucous membranesMucous membranes– OrthostaticsOrthostatics

Vital signsVital signs

Physical Exam ContinuedPhysical Exam Continued

• Dermatologic: Rashes, petechia, purpuraDermatologic: Rashes, petechia, purpura

• Abdomen: CVAT, enlarged bladder.Abdomen: CVAT, enlarged bladder.

• Mental Status: Altered Mental StatusMental Status: Altered Mental Status

• CV: Pericardial friction rubCV: Pericardial friction rub

What Do We Need to Do ? What Do We Need to Do ? Part 3Part 3• We need to act quickly to initiate workupWe need to act quickly to initiate workup

• Labs and Studies:Labs and Studies:

• Stat: Stat:

BMPBMP UA with microUA with micro

UnaUna UcrUcr

Uosm:Uosm:•>400 in pre-renal>400 in pre-renal

•<350 in post-renal<350 in post-renal

•<350 in intrinsic renal<350 in intrinsic renal

UA InterpretationUA Interpretation

• Hyaline CastsHyaline Casts: Not indicative of renal disease : Not indicative of renal disease – Concentrated urine, febrile disease, post-Concentrated urine, febrile disease, post-

strenuous exercise, diuretic therapystrenuous exercise, diuretic therapy

Granular CastsGranular Casts: Degenerating cellular casts, non-: Degenerating cellular casts, non-specificspecific

RBC CastsRBC Casts: Glomerulonephritis, vasculitis: Glomerulonephritis, vasculitis

WBC CastsWBC Casts: Pyelonephritis, Interstitial nephritis: Pyelonephritis, Interstitial nephritis

Renal Tubular Cell CastsRenal Tubular Cell Casts: Nonspecific, : Nonspecific, degenerating cellular castsdegenerating cellular casts

Waxy castsWaxy casts: Chronic renal failure: Chronic renal failure

Labs and Studies ContinuedLabs and Studies Continued• In oliguric ARF, calculate FeNa: In oliguric ARF, calculate FeNa:

• <1% (pre-renal, acute GN, contrast, hepatorenal),<1% (pre-renal, acute GN, contrast, hepatorenal),

• >1% Intrinsic renal failure (Damaged kidney can >1% Intrinsic renal failure (Damaged kidney can not concentrate urine, loses Na)not concentrate urine, loses Na)

Una/PnaUna/Pna x 100x 100

Ucr/PCrUcr/PCr

•FeNa has a 96% sensitivity and a 95% FeNa has a 96% sensitivity and a 95% specificity for distinguishing pre-renal from specificity for distinguishing pre-renal from ATN.ATN.

•Not accurate with diuretics.Not accurate with diuretics.

Studies and Labs ContinuedStudies and Labs Continued

• Renal UltrasoundRenal Ultrasound– r/o hydronephrosisr/o hydronephrosis– Bilateral Small Kidneys: Chronic Renal Bilateral Small Kidneys: Chronic Renal

DiseaseDisease– Unilateral Small Kidney: Renal Artery Unilateral Small Kidney: Renal Artery

StenosisStenosis– Enlarged Kidneys: HIV, amyloid, PCKD, Enlarged Kidneys: HIV, amyloid, PCKD,

early DMearly DM

TreatmentTreatment

• Place Foley or flush Foley if already present.Place Foley or flush Foley if already present.• As a large percentage of ARF is pre-renal, IVF As a large percentage of ARF is pre-renal, IVF

challenge appropriate in many cases.challenge appropriate in many cases.• Evaluate for life-threatening complications: Evaluate for life-threatening complications:

– A: A: – E:E:– (I):(I):– O:O:– U:U:

TreatmentTreatment• Place Foley or flush Foley if already present.Place Foley or flush Foley if already present.• As a large percentage of ARF is pre-renal, IVF As a large percentage of ARF is pre-renal, IVF

challenge appropriate in most cases.challenge appropriate in most cases.• Evaluate for life-threatening complications: Evaluate for life-threatening complications:

– A: AcidemiaA: Acidemia– E: Electrolyte Abnormalities (Hyperkalemia)E: Electrolyte Abnormalities (Hyperkalemia)– (I: Ingestion)(I: Ingestion)– O: Overload (CHF)O: Overload (CHF)– U: Uremic Encephalopathy or pericarditisU: Uremic Encephalopathy or pericarditis– ALL OF THE ABOVE ARE INDICATIONS FOR ALL OF THE ABOVE ARE INDICATIONS FOR

EMERGENT HEMODIALYSISEMERGENT HEMODIALYSIS

Treatment ContinuedTreatment Continued

• D/C all meds with kidney damaging potential D/C all meds with kidney damaging potential and adjust dosing of renally cleared meds.and adjust dosing of renally cleared meds.

• Monitor strict Is/Os, follow CBC to evaluate for Monitor strict Is/Os, follow CBC to evaluate for anemia and bleeding disorders.anemia and bleeding disorders.

• Control hyperkalemiaControl hyperkalemia• No longer recommended to give furosemide No longer recommended to give furosemide

to convert anuric to oliguric renal failure.to convert anuric to oliguric renal failure.• Consult renal for intra-renal or rapidly Consult renal for intra-renal or rapidly

progressive renal failure.progressive renal failure.

An Ounce of Prevention...An Ounce of Prevention...

• Check troughs after third dose of Check troughs after third dose of aminoglycosides.aminoglycosides.

• Use oral N-acetylcysteine or bicarbonate Use oral N-acetylcysteine or bicarbonate for contrast loads in patients with risk for contrast loads in patients with risk factors for ARF.factors for ARF.

• Avoid diagnostic studies involving Avoid diagnostic studies involving contrast unless absolutely necessary.contrast unless absolutely necessary.

• Monitor Is/Os in patients with ESLD, Monitor Is/Os in patients with ESLD, febrile states, prolonged NPO.febrile states, prolonged NPO.

Where Can I Learn More Where Can I Learn More About Acute Renal Failure?About Acute Renal Failure?• Acute Renal Failure Core Curriculum Acute Renal Failure Core Curriculum

HandoutHandout• Thadhani, et. Al., “Acute Renal Thadhani, et. Al., “Acute Renal

Failure,”NEJM, May 30, 1996 Review Failure,”NEJM, May 30, 1996 Review ArticleArticle

• Agrawal,N., et. Al., “Acute Renal Agrawal,N., et. Al., “Acute Renal Failure,” APF 2000;61:2077-2088.Failure,” APF 2000;61:2077-2088.

• Your local public libraryYour local public library