Acute kidney injury: Difference between revisions

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==Background==
==Background==
*Majority of cases of community-acquired ARF is secondary to volume depletion
*Majority of cases of community-acquired ARF is secondary to volume depletion although consideration of pre-renal, post renal, and renal causes are important.
===RIFLE Classification===
===AKI Staging===
*Risk - Serum Cr increased 1.5x baseline
{| {{table}}
*Injury - Serum Cr increased 2.0x baseline
| align="center" style="background:#f0f0f0;"|'''AKI Stage'''<ref>Moore PK, et. al. Management of acute kidney injury: core curriculum 2018. Am J Kidney Dis. 2018; 72: 136-148.</ref>
*Failure - Serum Cr increased 3.0x baseline OR Cr >4 and acute increase >0.5
| align="center" style="background:#f0f0f0;"|'''KDIGO'''
*Loss - Complete loss of kidney function for >4wk
| align="center" style="background:#f0f0f0;"|'''UOP'''
*[[ESRD]] - Need for renal replacement therapy for >3mo
|-
| 1||Cr 1.5-1.9x baseline over 7d '''or''' ≥0.3 mg/dL increase over 48hrs||<0.5 mL/kg/hr  for 6-12hrs
|-
| 2||Cr 2.0-2.9x baseline||<0.5 mL/kg/hr for >12hrs
|-
| 3||Cr ≥3.0x baseline '''or''' ≥4.0 mg/dL increase '''or''' initiation of RRT||<0.3 mL/kg/hr for >24hrs '''or''' anuria for >12hrs
|-
|}
===Chronic Kidney Disease Stages===
===Chronic Kidney Disease Stages===
*Useful if patient's baseline creatinine is unknown
*Useful if patient's baseline creatinine is unknown
**Stage 1: Kidney damage (e.g. proteinuria) and normal GFR; GFR >90
**Stage 1: Kidney damage (e.g. [[proteinuria]]) and normal GFR; GFR >90
**Stage 2: Kidney damage (e.g. proteinuria) and mild decrease in GFR; GFR 60-89
**Stage 2: Kidney damage (e.g. [[proteinuria]]) and mild decrease in GFR; GFR 60-89
**Stage 3: Moderate decrease in GFR; GFR >30-59
**Stage 3: Moderate decrease in GFR; GFR >30-59
**Stage 4: Severe decrease in GFR; GFR 15-29
**Stage 4: Severe decrease in GFR; GFR 15-29
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**Especiallyif GFR <60, hypovolemic  
**Especiallyif GFR <60, hypovolemic  
*Atherosclerosis
*Atherosclerosis
*Chronic hypertension
*Chronic [[hypertension]]
*Chronic kidney disease
*Chronic kidney disease
*NSAIDs
*[[NSAIDs]]
*ACEI/ARB
*[[ACEI]]/[[ARB]]
*[[Sepsis]]
*[[Sepsis]]
*[[Hypercalcemia]]
*[[Hypercalcemia]]
*Hepatorenal syndrome
*[[Hepatorenal syndrome]]


==Clinical Features==
==Clinical Features==
*Acute renal failure itself has few symptoms until severe uremia develops:
*Acute renal failure itself has few symptoms until severe uremia develops:
**[[Nausea/vomiting]], drowsiness, fatigue, confusion, coma
**[[Nausea/vomiting]], drowsiness, fatigue, confusion, [[coma]], [[pericarditis]]
*Patients more likely to present with symptoms related to underlying cause:
*Patients more likely to present with symptoms related to underlying cause:
**Prerenal
**Prerenal
***Thirst, orthostatic light-headedness, decreasing urine output
***Thirst, orthostatic lightheadedness, decreasing urine output
**Intrinsic
**Intrinsic
***[[Flank pain]], [[hematuria]]
***[[Flank pain]], [[hematuria]]
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****Papillary necrosis
****Papillary necrosis
****Crystal-induced nephropathy
****Crystal-induced nephropathy
***Myalgias, [[seizures]], recreational intoxication
***[[Myalgia]]s, [[seizures]], recreational intoxication
****Pigment-induced ARF ([[rhabdomyolysis]])
****Pigment-induced ARF ([[rhabdomyolysis]])
***Darkening urine and edema (esp with preceding pharyngitis or cutaneous infection)
***Darkening urine and edema (esp with preceding pharyngitis or cutaneous infection)
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****Acute interstitial nephritis
****Acute interstitial nephritis
***[[Cough]], [[dyspnea]], [[hemoptysis]]
***[[Cough]], [[dyspnea]], [[hemoptysis]]
****Goodpasture, granulomatosis with polyangiitis (Wegener's)
****[[Goodpasture syndrome]], [[granulomatosis with polyangiitis]] (Wegener's)
**Postrenal
**Postrenal
***Alternating oliguria and polyuria is pathognomonic of obstruction
***Alternating oliguria and [[polyuria]] is pathognomonic of obstruction
***Anuria
***Anuria


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[[File:Differential Diagnosis of Acute Kidney Injury.png|thumb]]
[[File:Differential Diagnosis of Acute Kidney Injury.png|thumb]]
===Prerenal===
===Prerenal===
*Hypovolemia
*[[Hypovolemia]]
**GI: decreased intake, vomiting and diarrhea
**GI: decreased intake, [[vomiting]] and [[diarrhea]]
**Pharmacologic: diuretics
**[[Hemorrhage]]
**Pharmacologic: [[diuretics]]
**Third spacing
**Third spacing
***[[Pancreatitis]]
***[[Pancreatitis]]
**Skin losses: fever, burns
**Skin losses: [[hyperthermia]], [[burns]]
**Miscellaneous
**Miscellaneous
***Hypoaldosteronism
***Hypoaldosteronism
***Salt-losing nephropathy
***Salt-losing nephropathy
***Postobstructive diuresis
***[[Postobstructive diuresis]]
*[[Hypotension]]
*[[Hypotension]]
**Septic vasodilation
**[[Sepsis]]
**Hemorrhage
**Decreased cardiac output: decompensated [[heart failure]], [[tamponade]], massive pulmonary embolus
**Decreased cardiac output
**[[Hepatorenal Syndrome]]
***Ischemia/infarction
***Ischemia/infarction
***Valvulopathy
***[[Valvular Disease|Valvulopathy]]
**Pharmacologic
**Pharmacologic
***beta-blockers
***[[Beta-blockers]]
***CCBs
***[[Calcium-channel blockers]]
***Antihypertensive medications
***[[Antihypertensive medications]]
**High-output failure
**[[High output heart failure]]
***[[Thyrotoxicosis]]
***[[Thyrotoxicosis]]
***AV fistula
***AV fistula
*Renal artery and small-vessel disease
*Renal artery and small-vessel disease
**Embolism: thrombotic, septic, cholesterol
**Embolism: thrombotic, septic, cholesterol
**Thrombosis: atherosclerosis, vasculitis, sickle cell disease
**Thrombosis: atherosclerosis, [[vasculitis]], [[sickle cell disease]]
**Dissection
**Dissection
**Pharmacologic
**Pharmacologic
***NSAIDs
***[[NSAIDs]]
***ACEI/ARB
***[[ACEI]]/[[ARB]]
****Observed shortly after initiation of therapy
****Observed shortly after initiation of therapy
**Microvascular thrombosis
**Microvascular thrombosis
***Preeclampsia
***[[Preeclampsia]]
***HUS
***[[Hemolytic Uremic Syndrome (HUS)]]
***DIC
***[[Thrombotic Thrombocytopenic Purpura (TTP)]]
***vasculitis
***[[Disseminated Intravascular Coagulation (DIC)]]
***SCD
***[[Vasculitis]]
**Hypercalcemia
***[[Sickle Cell Disease]]
**[[Hypercalcemia]]


===Intrinsic===
===Intrinsic===
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***Caused by more advanced disease due to the prerenal causes
***Caused by more advanced disease due to the prerenal causes
*Nephrotoxins
*Nephrotoxins
**Aminoglycosides, [[Contrast-Induced Nephropathy|radiocontrast]], [[amphotericin B]], heme pigments ([[rhabdomyolysis]], hemolysis)
**[[Aminoglycosides]], [[Contrast-Induced Nephropathy|radiocontrast]], [[amphotericin B]], heme pigments ([[rhabdomyolysis]], hemolysis)
**Obstruction
**Obstruction
***Uric acid, calcium oxalate, myeloma, amyloid
***Uric acid, calcium oxalate from [[Ethylene Glycol Toxicity]], [[Multiple myeloma]] (immunoglobin light chains), [[amyloidosis]]
***Pharmacologic: sulfonamide, triamterene, acyclovir, indinavir
***Pharmacologic: [[sulfonamides]], triamterene, [[acyclovir]], indinavir
*Interstitial diseases
*Interstitial diseases
**Acute interstitial nephritis: typically a drug reaction ([[NSAIDs]], antibiotics, [[phenytoin]])
**Acute interstitial nephritis: typically a drug reaction ([[NSAIDs]], [[Penicillins]] and antibiotics, [[Diuretics]], [[phenytoin]])
**Infection: bilateral pyelonephritis, Legionnaire disease, hantavirus
**Infection: bilateral pyelonephritis, [[Legionella]], [[Hantavirus]]
**Infiltrative disease: sarcoidosis, lymphoma
**Infiltrative disease: [[sarcoidosis]], [[lymphoma]]
**Autoimmune diseases: [[SLE]]
**Autoimmune diseases: [[SLE]]
*Glomerular diseases
*Glomerular diseases
**Rapidly progressive glomerulonephritis
**Rapidly progressive glomerulonephritis
***Goodpasture, granulomatosis with polyangiitis (Wegener's) [[HSP]], [[SLE]], membranoproliferative GN
***[[Goodpasture syndrome]], [[granulomatosis with polyangiitis]] (Wegener's) [[HSP]], [[SLE]], membranoproliferative GN
**Postinfectious glomerulonephritis
**Postinfectious [[glomerulonephritis]]
*Small-vessel diseases
*Small-vessel diseases
**Microvascular thrombosis
**Microvascular thrombosis
***Preeclampsia, [[HUS]], [[DIC]], [[TT]]P, vasculitis (PAN, SCD, atheroembolism)
***[[Preeclampsia]], [[HUS]], [[DIC]], [[Thrombotic Thrombocytopenic Purpura (TTP)|TTP]], [[vasculitis]] (PAN, SCD, atheroembolism)
**Malignant hypertension
**[[Malignant hypertension]]
**Scleroderma
**[[Scleroderma]]
**Renal vein thrombosis
**Renal vein thrombosis
*[[Abdominal compartment syndrome]]
*[[Hepatorenal syndrome]]
*[[Cardiorenal syndrome]]


===Postrenal===
===Postrenal===
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***Blood clot
***Blood clot
**Urethra and bladder outlet
**Urethra and bladder outlet
***Phimosis or urethral stricture (male preponderance)
***[[Phimosis]] or urethral stricture (male preponderance)
***Neurogenic bladder
***Neurogenic bladder
****DM, spinal cord disease, multiple sclerosis, Parkinson's
****[[Diabetes mellitus]], spinal cord disease, [[multiple sclerosis]], [[Parkinson's disease]]
****Pharmacologic: anticholinergics, a-adrenergic antagonists, opioids
****Pharmacologic: [[anticholinergics]], [[alpha antagonist|a-adrenergic antagonists]], [[opioids]]
*Adults
*Adults
**Urethra and bladder outlet
**Urethra and bladder outlet
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***Obstructed catheters
***Obstructed catheters
**Ureter
**Ureter
***Calculi, uric acid crystals
***[[Ureteral calculi]], uric acid crystals
***Papillary necrosis
***Papillary necrosis
****SCD, DM, pyelonephritis
****[[Sickle cell disease]], [[DM]], [[pyelonephritis]]
***Tumor: Ureter, uterus, prostate, bladder, colon, rectum; retroperitoneal lymphoma
***Tumor: Ureter, uterus, prostate, bladder, colon, rectum; retroperitoneal lymphoma
***Retroperitoneal fibrosis: idiopathic, tuberculosis, sarcoidosis, propranolol
***Retroperitoneal fibrosis: idiopathic, [[tuberculosis]], [[sarcoidosis]], [[propranolol]]
***Stricture: TB, radiation, schistosomiasis, NSAIDs
***Stricture: [[TB]], [[Radiation exposure|radiation]], [[schistosomiasis]], [[NSAIDs]]
***Miscellaneous
***Miscellaneous
****Aortic aneurysm
****[[Abdominal aortic aneurysm|Aortic aneurysm]]
****Pregnant uterus
****Pregnant uterus
****IBD
****[[IBD]]
****Trauma
****[[Renal trauma|Renal]] or [[ureter trauma]]


==Evaluation==
==Evaluation==
*Prerenal
*Prerenal
**BUN/Cr ratio > 20
**BUN/creatinine ratio > 20
**FeNa <1% ((urine sodium/plasma sodium) / (urine creatinine / serum creatinine))
**FeNa <1% ((urine sodium/plasma sodium) / (urine creatinine / serum creatinine))
***< 2% for neonates
***< 2% for neonates
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*Urine
*Urine
*Prostate exam
*Prostate exam
*UA, urine sodium, urine creatinine, urine urea
*[[Urinalysis]], urine sodium, urine creatinine, urine urea
*ECG (hyperkalemia)
*[[ECG]] (hyperkalemia)
*Chronic renal failure features
**Anemia, thrombocytopenia
**Iron studies with low Fe, low TIBC, low iron saturation, normal ferritin
**Secondary rise in PTH, high phos, low calcium


===Imaging===
===Imaging===
*CXR
*[[CXR]]
*Evidence of volume overload, pneumonia
**Evidence of volume overload, pneumonia
*US
*US: [[renal ultrasound|renal]]/[[bladder ultrasound|bladder]]
**Test of choice in setting of acute renal failure
**Test of choice in setting of acute renal failure
**Bladder size (post-void)
**Bladder size (post-void)
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**Useful to determine cause of post renal failure (identification of abdominal masses etc.)
**Useful to determine cause of post renal failure (identification of abdominal masses etc.)
**Should generally not be used with IV contrast due to potential risk for [[Contrast-Induced Nephropathy|CIN]]
**Should generally not be used with IV contrast due to potential risk for [[Contrast-Induced Nephropathy|CIN]]
**Indicated if hydronephrois found on US in order to define the location of obstruction
**Indicated if hydronephrosis found on [[ultrasound]] in order to define the location of obstruction


==Management==
==Management==
''Treat underlying cause''
''Treat underlying cause''
*Prerenal: IVF
*Prerenal: [[IVF]] (or [[pRBCs]] if bleeding)
*Intrinsic: Depends on cause
*Intrinsic: Depends on cause
*Obstruction:
*Obstruction:
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**Suprapubic (if Coude fails)
**Suprapubic (if Coude fails)


===Dialysis===
===[[Dialysis]]===
*Indicated for:
*Indicated for:
**A: Acidosis (severe)
**A: [[Acidosis]] (severe)
**E: Electrolyte abnormality (e.g. uncontrolled hyperkalemia)
**E: [[Electrolyte abnormality]] (e.g. uncontrolled [[hyperkalemia]])
**I: Ingestions (lithium, ASA, methanol, ethylene glycol, theophylline)
**I: Ingestions ([[lithium toxicity|lithium]], [[salicylate toxicity|ASA]], [[methanol]], [[ethylene glycol]], [[theophylline toxicity|theophylline]])
**O: Overload (volume) with persistent hypoxia
**O: [[fluid overload|Overload]] (volume) with persistent hypoxia
**U: Uremic pericarditis/encephalopathy/bleeding dyscrasia
**U: [[uremia|Uremic]] [[pericarditis]]/[[encephalopathy]]/[[coagulopathy|bleeding dyscrasia]]
**Also:
**Also:
***Na <115 or >165 mEq/L
***Na <115 or >165 mEq/L
***Cr > 10
***creatinine > 10
***BUN >100
***BUN >100
*See [[Dialysis catheter placement]]
*See [[Austere peritoneal dialysis]]
===Phlebotomy to Treat [[Pulmonary Edema]]===
*Possible last ditch effort to tide patient over to formal dialysis if hours away
*If traditional pulmonary edema treatments are not working for [[Sympathetic crashing acute pulmonary edema (SCAPE)|SCAPE]] patient, one may attempt to remove 200-300 cc of blood as a bridge to dialysis<ref>Eiser AR et al. Phlebotomy for pulmonary edema in dialysis patients. Clin Nephrol. 1997 Jan;47(1):47-9.</ref>
*If Hb too low, may consider temporary venous tourniquets on each leg proximally q30 min to reduce preload volume to the heart, alternating legs


==Disposition==
==Disposition==
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*[[Renal ultrasound]]
*[[Renal ultrasound]]
*[[Hypertensive emergency]]
*[[Hypertensive emergency]]


==External Links==
==External Links==
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==References==
==References==
<references/>


[[Category:Renal]]
[[Category:Renal]]

Revision as of 04:32, 4 May 2020

Background

  • Majority of cases of community-acquired ARF is secondary to volume depletion although consideration of pre-renal, post renal, and renal causes are important.

AKI Staging

AKI Stage[1] KDIGO UOP
1 Cr 1.5-1.9x baseline over 7d or ≥0.3 mg/dL increase over 48hrs <0.5 mL/kg/hr for 6-12hrs
2 Cr 2.0-2.9x baseline <0.5 mL/kg/hr for >12hrs
3 Cr ≥3.0x baseline or ≥4.0 mg/dL increase or initiation of RRT <0.3 mL/kg/hr for >24hrs or anuria for >12hrs

Chronic Kidney Disease Stages

  • Useful if patient's baseline creatinine is unknown
    • Stage 1: Kidney damage (e.g. proteinuria) and normal GFR; GFR >90
    • Stage 2: Kidney damage (e.g. proteinuria) and mild decrease in GFR; GFR 60-89
    • Stage 3: Moderate decrease in GFR; GFR >30-59
    • Stage 4: Severe decrease in GFR; GFR 15-29
    • Stage 5: Kidney failure (dialysis or kidney transplant needed); GFR <15

Risk Factors

Clinical Features

Etiologies

Differential Diagnosis of Acute Kidney Injury.png

Prerenal

Intrinsic

Postrenal

Evaluation

  • Prerenal
    • BUN/creatinine ratio > 20
    • FeNa <1% ((urine sodium/plasma sodium) / (urine creatinine / serum creatinine))
      • < 2% for neonates
    • Urine osm >500
    • Urine sodium < 20 mEq/L
    • Specific gravity > 1.020
    • Fractional excretion of urea < 35%
    • Microscopic analysis
      • Hyaline casts
  • Instrinsic
    • FeNa >1%
      • > 2.5% for neonates
    • Urine Osm <350
    • Urine sodium > 40 mEq/L
    • Specific gravity < 1.020
    • Fractional excretion of urea > 50%
    • Microscopic analysis
      • Acute glomerulonephritis: RBCs, casts
      • Acute tubular necrosis: protein, tubular epithelial cells
  • Postrenal
    • FeNa >1%
    • Urine Osm <350

Work-up

  • Urine
  • Prostate exam
  • Urinalysis, urine sodium, urine creatinine, urine urea
  • ECG (hyperkalemia)
  • Chronic renal failure features
    • Anemia, thrombocytopenia
    • Iron studies with low Fe, low TIBC, low iron saturation, normal ferritin
    • Secondary rise in PTH, high phos, low calcium

Imaging

  • CXR
    • Evidence of volume overload, pneumonia
  • US: renal/bladder
    • Test of choice in setting of acute renal failure
    • Bladder size (post-void)
    • Hydronephrosis
    • IVC collapsibility (prerenal)
  • CT
    • Useful to determine cause of post renal failure (identification of abdominal masses etc.)
    • Should generally not be used with IV contrast due to potential risk for CIN
    • Indicated if hydronephrosis found on ultrasound in order to define the location of obstruction

Management

Treat underlying cause

  • Prerenal: IVF (or pRBCs if bleeding)
  • Intrinsic: Depends on cause
  • Obstruction:
    • Note: Postobstructive diuresis can result in significant volume loss and death
      • Typically occurs when obstruction has been prolonged / has resulted in renal failure
      • Admit patients with persistent diuresis of >250 mL/h for >2hr
    • Foley Catheter, consider Coude Catheter
    • Suprapubic (if Coude fails)

Dialysis

Phlebotomy to Treat Pulmonary Edema

  • Possible last ditch effort to tide patient over to formal dialysis if hours away
  • If traditional pulmonary edema treatments are not working for SCAPE patient, one may attempt to remove 200-300 cc of blood as a bridge to dialysis[2]
  • If Hb too low, may consider temporary venous tourniquets on each leg proximally q30 min to reduce preload volume to the heart, alternating legs

Disposition

  • Admit

See Also

External Links

References

  1. Moore PK, et. al. Management of acute kidney injury: core curriculum 2018. Am J Kidney Dis. 2018; 72: 136-148.
  2. Eiser AR et al. Phlebotomy for pulmonary edema in dialysis patients. Clin Nephrol. 1997 Jan;47(1):47-9.