From the Guidelines
Acute Kidney Injury (AKI) is defined as an increase in creatinine by 0.3 mg/dL within 48 hours or an increase in serum creatinine to 1.5 times baseline within 7 days or urine volume 0.5 mL/kg/hr for 6 hours, as stated in the most recent guidelines 1.
Definition and Classification of AKI
The definition of AKI is crucial for early recognition and management. According to the KDIGO guidelines, AKI is categorized into three stages of increasing severity based on the magnitude of creatinine elevation or degree of oliguria.
- Stage 1: Increase in SCr 1.5-1.9 times baseline OR 0.3 mg/dL OR urine output 0.5 mL/kg/h for 6-12 hours
- Stage 2: Increase in SCr 2.0-2.9 times baseline OR urine output 0.5 mL/kg/h for 12 hours
- Stage 3: Increase in SCr 3.0 times baseline OR increase in SCr to 4.0 mg/dL OR initiation of renal replacement therapy OR, in patients 18 years, decrease in eGFR to 35 mL/min/1.73 m2, OR urine output 0.3 mL/kg/h for 24 hours OR anuria for 12 hours, as outlined in the KDIGO guidelines 2.
Importance of Early Recognition and Management
Early recognition of AKI is crucial as it can lead to electrolyte imbalances, metabolic acidosis, fluid overload, and in severe cases, the need for renal replacement therapy. Management focuses on treating the underlying cause, maintaining adequate hydration, avoiding further kidney injury, and supporting kidney function until recovery occurs.
- Common causes of AKI include dehydration, sepsis, nephrotoxic medications (NSAIDs, aminoglycosides, contrast media), and urinary tract obstruction, as noted in the literature 3.
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The KDIGO guidelines provide a framework for the definition and classification of AKI, which is essential for early recognition and management. By understanding the definition and classification of AKI, healthcare providers can provide timely and effective treatment, improving patient outcomes and reducing morbidity and mortality.
- The KDIGO guidelines are widely accepted and used in clinical practice, and their implementation has been shown to improve patient outcomes, as stated in the guidelines 1, 2, 3.
From the Research
Definition of AKI
- Acute kidney injury (AKI) is defined by a sudden loss of excretory kidney function 4
- AKI is characterized by abrupt deterioration in kidney function, manifested by an increase in serum creatinine level with or without reduced urine output 5
- AKI can be defined as an increase in serum creatinine or a decrease in urine output over hours to days 6
- AKI is a clinical syndrome characterized by a rapid decline in glomerular filtration rate and resultant accumulation of metabolic waste products 7
Key Characteristics of AKI
- AKI is a heterogeneous disorder that is common in hospitalized patients and associated with short- and long-term morbidity and mortality 8
- The spectrum of injury ranges from mild to advanced, sometimes requiring renal replacement therapy 5
- AKI has a poor prognosis in critically ill patients, with long-term consequences including chronic kidney disease (CKD) and cardiovascular morbidity 4