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===
===RIFLE Classification===
*Risk - Serum creatinine increased 1.5x baseline
*Risk - Serum creatinine increased 1.5x baseline
*Injury - Serum creatinine increased 2.0x baseline
*Injury - Serum creatinine increased 2.0x baseline
*Failure - Serum creatinine increased 3.0x baseline OR creatinine >4 and acute increase >0.5
*Failure - Serum creatinine increased 3.0x baseline '''OR''' creatinine >4 and acute increase >0.5
*Loss - Complete loss of kidney function for >4wk
*Loss - Complete loss of kidney function for >4wk
*[[ESRD]] - Need for renal replacement therapy for >3mo
*[[ESRD]] - Need for renal replacement therapy for >3mo
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*Hypovolemia
*Hypovolemia
**GI: decreased intake, vomiting and diarrhea
**GI: decreased intake, vomiting and diarrhea
**Hemorrhage
**Pharmacologic: diuretics
**Pharmacologic: diuretics
**Third spacing
**Third spacing
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***Postobstructive diuresis
***Postobstructive diuresis
*[[Hypotension]]
*[[Hypotension]]
**Septic vasodilation
**[[Sepsis]]
**Hemorrhage
**Decreased cardiac output
**Decreased cardiac output
**[[Hepatorenal Syndrome]]
***Ischemia/infarction
***Ischemia/infarction
***Valvulopathy
***[[Valvular Disease|Valvulopathy]]
**Pharmacologic
**Pharmacologic
***beta-blockers
***[[Beta-blockers]]
***calcium-channel blockers
***[[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), amyloid
***Pharmacologic: sulfonamide, triamterene, acyclovir, indinavir
***Pharmacologic: sulfonamide, 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, [[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
****Pharmacologic: anticholinergics, a-adrenergic antagonists, opioids
****Pharmacologic: anticholinergics, a-adrenergic antagonists, opioids
*Adults
*Adults
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****SCD, DM, pyelonephritis
****SCD, 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
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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===
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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 hydronephrois found on [[ultrasound]] in order to define the location of obstruction


==Management==
==Management==
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***creatinine > 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 [[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 16:08, 21 April 2019

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.

RIFLE Classification

  • Risk - Serum creatinine increased 1.5x baseline
  • Injury - Serum creatinine increased 2.0x baseline
  • Failure - Serum creatinine increased 3.0x baseline OR creatinine >4 and acute increase >0.5
  • Loss - Complete loss of kidney function for >4wk
  • ESRD - Need for renal replacement therapy for >3mo

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

  • Acute renal failure itself has few symptoms until severe uremia develops:
  • Patients more likely to present with symptoms related to underlying cause:
    • Prerenal
      • Thirst, orthostatic light-headedness, decreasing urine output
    • Intrinsic
    • Postrenal
      • Alternating oliguria and polyuria is pathognomonic of obstruction
      • Anuria

Etiologies

Differential Diagnosis of Acute Kidney Injury.png

Prerenal

Intrinsic

Postrenal

  • Infants and children
    • Urethra and bladder outlet
      • Anatomic malformations
        • Urethral atresia
        • Meatal stenosis
        • Anterior and posterior urethral valves
    • Ureter
      • Anatomic malformations
        • Vesicoureteral reflux (female preponderance)
        • Ureterovesical junction obstruction
        • Ureterocele
        • Retroperitoneal tumor
  • All ages
    • Various locations in GU tract
      • Trauma
      • Blood clot
    • Urethra and bladder outlet
      • Phimosis or urethral stricture (male preponderance)
      • Neurogenic bladder
        • Diabetes mellitus, spinal cord disease, multiple sclerosis, Parkinson's
        • Pharmacologic: anticholinergics, a-adrenergic antagonists, opioids
  • Adults
    • Urethra and bladder outlet
      • BPH
      • Cancer of prostate, bladder, cervix, or colon
      • Obstructed catheters
    • Ureter

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
    • 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 hydronephrois found on ultrasound in order to define the location of obstruction

Management

Treat underlying cause

  • Prerenal: IVF
  • 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

  • Indicated for:
    • A: Acidosis (severe)
    • E: Electrolyte abnormality (e.g. uncontrolled hyperkalemia)
    • I: Ingestions (lithium, ASA, methanol, ethylene glycol, theophylline)
    • O: Overload (volume) with persistent hypoxia
    • U: Uremic pericarditis/encephalopathy/bleeding dyscrasia
    • Also:
      • Na <115 or >165 mEq/L
      • creatinine > 10
      • 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 SCAPE patient, one may attempt to remove 200-300 cc of blood as a bridge to dialysis[1]
  • 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. Eiser AR et al. Phlebotomy for pulmonary edema in dialysis patients. Clin Nephrol. 1997 Jan;47(1):47-9.