Acute Renal Failure

From Anvita Health Wiki

Contents 1 More Specific Terms 2 Introduction 3 Etiology 4 Pathology 5 History 6 Clinical-manifestations 7 Laboratory 8 Radiology 9 Management 10 More General Terms 11 Additional Terms 12 References

More Specific Terms

• acute renal cortical necrosis
• acute renal failure in malignancy
• acute renal failure in pregnancy
• acute tubular necrosis (ATN)
• atheroembolic renal failure

Introduction

• An abrupt decline in renal function that occurs over hours to days.

Etiology

• prerenal (70% of community-, 40% of hospital-acquired ARF)

• volume depletion

• GI losses

• diarrhea
• vomiting

• blood loss
• inadequate fluid intake
• insensible losses - sweating

• diminished effective blood volume

• hypotension

• sepsis
• excessive response to antihypertensive agent

• heart failure
• liver failure

• vasospasm

• ischemia
• cyclosporine
• malignant hypertension
• pre-eclampsia

• bilateral renal artery occlusion
• common mechanism is ischemia
• elderly are especially susceptible to pre-renal azotemia

• predisposition to hypovolemia
• prevalence of renal artery atherosclerosis

• intrinsic renal failure

• acute tubular necrosis (85%)

• prolonged ischemia (50%) - sustained pre-renal azotemia
• nephrotoxic agents (35%)

• heavy metals
• aminoglycosides
• radiographic contrast media

• ARF within 24 hr with rapid resolution
• especially hazardous in diabetics with serum creatinine > 2 mg/dL

• amphotericin B
• myoglobin

• combined factors involving nephrotoxins

• aminoglycoside & sepsis
• radiocontrast agent & ACE inhibitor
• NSAID & congestive heart failure ( CHF)

• arteriolar injury

• accelerated hypertension
• vasculitis
• microangiopathic

• TTP/ HUS
• preeclampsia
• sickle cell disease
• snake bite

• hypercalcemia
• scleroderma

• glomerulonephropathies (5%)
• acute interstitial nephritis ( AIN) (10%)

• allergic reaction to drug (most common)
• autoimmune disease ( SLE)
• sarcoidosis
• infectious agents

• Legionella
• Hantavirus

• intrarenal deposition/ precipitation

• uric acid
• immunoglobulin in myeloma

• atheroembolic renal failure ( cholesterol embolization)

• post arterial procedure, i.e. left heart catheterization
• ARF after 24 hr (slower onset than ARF secondary to radiographic contrast media)
• other evidence of cholesterol emboli
• poor prognosis for recovery of renal function

• atherosclerosis

• renal artery atherosclerotic plaque
• dissecting aneurysm affecting renal artery

• renal allograft rejection
• renal cortical necrosis (complete anuria)

• postrenal

• ureteral obstruction

• clot
• calculus - oxalate
• sloughed papillae ( papillary necrosis)
• external compression

• tumor ( colon)
• retroperitoneal fibrosis

• bladder outlet obstruction (98% of males)

• neurogenic bladder
• prostatic hypertrophy
• carcinoma ( prostate, cervix, bladder)
• calculus
• clot
• urethral stricture

• bilateral renal vein occlusion ( thrombosis)

• risk factors

• chronic renal failure
• proteinuria

• diabetic nephropathy

• heart failure
• liver disease
• hypovolemia
• age > 50 years
• medications, especially NSAIDs, ACE inhibitors, ARBs, diuretics [10]

Pathology

• complete or partial impairment of renal function resulting in an increase of serum creatinine of 0.5-2.0 mg/ dL/day
• with complete renal failure, serum creatinine increases 1-2 mg/ dL/day
• an increase of serum creatinine of 1 mg/ dL/day indicates a creatinine clearance of < 10 mL/min

History

• nephrotoxic agents (see etiology)

Clinical-manifestations

• generally non-specific
• dependent upon rapidity of onset
• symptoms of uremia
• gastrointestinal:

• anorexia
• nausea/vomiting
• diarrhea/ constipation
• metallic taste

• cardiovascular:

• shortness of breath
• dyspnea on exertion
• edema: lower extremity, periorbital

• hematologic:

• symptoms of anemia
• symptoms of thrombocytopenia

• genitourinary:

• oliguria or anuria
• costovertebral angle ( CVA) tenderness
• hematuria
• foamy urine

Laboratory

• serum chemistries

• serum creatinine
• serum urea nitrogen
• serum potassium
• serum bicarbonate
• serum transaminases
• serum creatine kinase

• complete blood count ( CBC)

• white blood cell count (WBC)
• hematocrit
• platelet count

• peripheral blood smear:

• schistocytes, evidence of hemolysis ( TTP/ HUS)

• urinalysis

• specific gravity:

• > 1.018 prerenal azotemia
• < 1.012 intrinsic renal failure

• red blood cells (RBC)
• white blood cells (WBC)

• urine eosinophils ( AIN, cholesterol emboli)
• pyuria ( pyelonephritis, AIN)

• urine protein
• RBC casts: intrinsic renal failure, glomerulonephritis
• hyaline casts ( prerenal azotemia)
• muddy brown, broad casts ( ATN)

• urine chemistries

• fractional excretion of sodium ( FENA)

• < 1% prerenal & glomerulonephritis
• > 1% renal or post renal ( ATN, obstructive uropathy)

• urine sodium:

• < 20 meq/L prerenal
• > 40 meq/L renal ( ATN)
• < 40 meq/L acute glomerulonephritis

• osmolality:

• > 500 mosm/kg prerenal azotemia
• < 250 msom/kg intrinsic renal failure

• urine/ serum creatinine ratio

• > 40 prerenal azotemia
• < 20 intrinsic renal failure

• renal failure index

• urine myoglobin of questionable utility
• serologies

• CH50 for complement deficiency
• antinuclear antibody ( ANA)
• antistreptolysin O ( ASO) titer
• antiglomerular basement membrane ( anti GBM) titer
• anti-neutrophil cytoplasmic antibody ( ANCA)

• serum protein electrophoresis
• urine protein electrophoresis - Bence-Jones proteins
• 24 hour urine

• creatinine clearance
• 24-hour urine protein: nephrotic syndrome
• oliguria, anuria

• renal biopsy

• diagnosis remains unclear
• pre-renal & post-renal etiologies excluded

Radiology

• ultrasound

• renal

• kidney size, solitary kidney

• large kidney - amyloidosis, early diabetes, HIV nephropathy
• small kidney

• hydronephrosis

• may not show hydronephrosis within 24 hours of onset or with retroperitoneal fibrosis

• evidence of obstruction

• nephrolithiasis
• BPH with obstruction
• tumor
• retroperitoneal fibrosis

• pelvic

• pyelogram - gold standard, but seldom utilized
• renal flow scan

Management

• monitor input & output - foley catheter
• optimize intravascular volume

• a fluid challenge is indicated in the absence of volume overload:

• 500-1000 mL of normal saline over 30-60 min
• increased urine flow may result in patients with:

• prerenal azotemia
• patients with intrinsic renal disease

• if no response to saline bolus

• 100 to 400 mg of IV Lasix
• metolazone 5-10 mg PO in addition to Lasix may facilitate urine output

• loop diuretic if volume overloaded of uncertain benefit [6,8]
• invasive monitoring of central venous pressure may be indicated
• IV albumin for cirrhotic patients with intravascular volume depletion
• dopamine & mannitol of no value

• optimize cardiac output
• avoid further renal insults

• discontinue nephrotoxic agents

• ACE inhibitors
• diuretics
• cyclosporine
• NSAIDs

• avoid contrast agents
• dose adjustment as needed for renally-cleared pharmaceutical agents

• treat hyperkalemia
• treat underlying conditions

• sepsis - antibiotics
• glomerulonephritis - immunosuppressive agents
• relieve obstruction - foley catheter
• metabolic acidosis: IV bicarbonate or hemodialysis
• hypertension:

• vasodilators, beta-blockers, calcium-channel blockers
• avoid renally-cleared antihypertensives

• fluid restriction if euvolemic or volume overloaded

• 1 to 1.5 L/day

• avoid Mg+2 containing antacids
• hemodialysis

• indications:

• refractory hyperkalemia
• refractory acidosis ( pH < 7.20)
• volume overload
• signs or symptoms of uremia

• altered mental status
• asterixis
• pericardial friction rub
• vomiting

• prolonged acute renal failure (> a few days)
• do not withhold dialysis until BUN & serum creatinine reach a threshold vaule

• continuous replacement therapies

• continuous venovenous hemofiltration ( CVVH)
• continuous arteriovenous hemofiltration ( CAVH)
• treatment of choice in patients who are hemodynamically unstable & unable to tolerate standard hemodialysis

• diet

• protein restriction for control of uremia (do not restrict dietary protein in acute renal failure) [5]
• sodium restriction < 2 g/day
• potassium restriction < 2 g/day
• phosphate restriction & PhosLo ( calcium acetate)

• post- acute tubular necrosis ( ATN) diuresis

• generally occurs prior to drop in creatinine
• avoid volume depletion

• treatment of hyperuricemia generally not necessary if serum uric acid is < 15 mg/dL
• prevention:

• fenoldopam may reduce risk of acute renal failure in critically ill patients

More General Terms

• renal failure; kidney failure

Additional Terms

• fractional excretion of sodium (FENA)
• glomerulonephritis (GN, nephritic syndrome)
• immediate treatment of acute renal failure (ARF)
• interstitial nephritis
• nephrotoxic substances
• postrenal azotemia; obstructive uropathy
• prerenal azotemia
• renal failure index (RFI)
• uremia
• vasculitis

References

1. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 263-268
2. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 535-537
3. Thadhani R et al Acute renal failure. N Engl J Med 334:1448 1996 PMID: [1]
4. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 596-98
5. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, American College of Physicians, Philadelphia 1998, 2006, 2009
6. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 1266
7. Journal Watch 24(20):150, 2004 Cantarovich F, Rangoonwala B, Lorenz H, Verho M, Esnault VL. High-dose furosemide for established ARF: a prospective, randomized, double-blind, placebo-controlled, multicenter trial. Am J Kidney Dis. 2004 Sep;44(3):402-9. PMID: [2]
8. Ho KM and Sheridan DJ Meta-analysis of furosemide to prevent or treat acute renal failure. BMJ 2006, 333:420 PMID: [3]
9. James MT et al Glomerular filtration rate, proteinuria, and the incidence and consequences of acute kidney injury: A cohort study. Lancet 2010 Dec 18; 376:2096 PMID: [4]
10. Geriatric Review Syllabus, 7th edition Parada JT et al (eds) American Geriatrics Society, 2010

acute renal failure (ARF)