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For further information, see CMDT Part 24-04: Acute Kidney Injury

KEY FEATURES

Essentials of Diagnosis

  • Rapid increase in serum creatinine

  • Oliguria may be present

  • Symptoms and signs depend on cause and severity

General Considerations

  • Defined as an absolute increase in serum creatinine by ≥ 0.3 mg/dL over 48 hours or relative increase to ≥ 1.5 times baseline that is known or presumed to have occurred within 7 days

  • Characterized as oliguric if urine production is < 400–500 mL/d

  • 20% of all hospitalized patients and 65% of ICU admissions have acute kidney injury (AKI)

  • The 2012 Kidney Disease Improving Global Outcomes (KDIGO) Clinical Practice Guidelines for Acute Kidney Injury describes three progressive stages based on the degree of elevation in serum creatinine or decline in urinary output

    • Stage 1: 1.5- to 1.9-fold increase in serum creatinine or a decline in urinary output to 0.5 mL/kg/h over 6–12 hours

    • Stage 2: 2.0–2.9-fold increase in serum creatinine or a decline in urinary output to 0.5 mL/kg/h for > 12 hours

    • Stage 3: 3-fold or greater increase in serum creatinine, an increase in serum creatinine to ≥ 4 mg/dL, or a decline in urinary output to < 0.3 mL/kg/h for ≥ 24 hours, anuria for ≥ 12 hours, or initiation of kidney replacement therapy

  • Serum creatinine concentration can typically increase by 1.0–1.5 mg/dL daily, although in certain conditions such as rhabdomyolysis serum creatinine can increase more rapidly

  • Patients with AKI from any cause are at higher risk for all-cause mortality even if there is substantial renal recovery

CLINICAL FINDINGS

Symptoms and Signs

  • Can be asymptomatic

  • Uremia: Nausea, vomiting, malaise, altered sensorium

  • Hypertension

  • Pericardial friction rub, effusions, and cardiac tamponade

  • Hyperkalemia: Heart block and ventricular tachycardia

  • Prolonged bleeding time due to platelet dysfunction

  • Asterixis, encephalopathy, seizures

  • Oliguria

Differential Diagnosis

Table 24–3.Classification and differential diagnosis of AKI.

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