Acute Kidney Injury (AKI) – A Comprehensive Clinical Guide
Acute Kidney Injury (AKI)—previously called acute renal failure—is a sudden decline in kidney function occurring over hours to days. It leads to impaired excretion of waste products, electrolyte imbalance, and fluid dysregulation. AKI is a medical emergency when unrecognized and untreated, but early diagnosis and timely management can fully reverse kidney function in many patients.
Definition
AKI is defined as:
Increase in serum creatinine by ≥0.3 mg/dL within 48 hours, or
Increase in serum creatinine to ≥1.5 times baseline within 7 days, or
Urine output <0.5 mL/kg/hour for ≥6 hours
Epidemiology & Importance
Common in hospitalized and ICU patients
Higher risk in elderly, diabetics, hypertensives, septic patients
Associated with high morbidity and mortality if delayed
Classification of AKI (Etiology-Based)
1. Prerenal AKI (सबसे common)
Due to reduced renal perfusion
Causes:
Dehydration, vomiting, diarrhea
Hemorrhage
Sepsis, shock
Heart failure
Overuse of diuretics / NSAIDs
🔹 Reversible if corrected early
2. Intrinsic (Renal) AKI
Due to direct kidney damage
Common causes:
Acute Tubular Necrosis (ATN) – ischemia, toxins
Acute Interstitial Nephritis (AIN) – drugs, infections
Glomerulonephritis
Vasculitis
🔹 Recovery depends on severity and early treatment
3. Postrenal AKI
Due to urinary tract obstruction
Causes:
Prostate enlargement (BPH)
Ureteric stones
Tumors
Urethral stricture
🔹 Often completely reversible after relieving obstruction
Clinical Features (Symptoms & Signs)
Decreased urine output (oliguria/anuria)
Facial or pedal edema
Breathlessness (fluid overload)
Nausea, vomiting
Confusion (uremia)
Palpitations (electrolyte imbalance)
⚠️ Some patients may be asymptomatic initially
Diagnostic Evaluation
Laboratory Tests
Serum urea & creatinine
Electrolytes (Na⁺, K⁺, HCO₃⁻)
Complete blood count
Urine routine & microscopy
Urine sodium, FeNa (selected cases)
Imaging
Ultrasound KUB – kidney size, obstruction
Others (as needed)
ABG, ECG (for hyperkalemia)
Autoimmune markers, renal biopsy (selected cases)
Management of AKI
General Principles
Early identification & cause correction
Maintain adequate perfusion
Avoid nephrotoxic drugs
Monitor urine output & labs closely
Cause-Specific Treatment
🔹 Prerenal AKI
IV fluids
Treat sepsis/shock
Optimize cardiac output
🔹 Intrinsic AKI
Remove offending drugs
Treat infections
Steroids/immunosuppressants (when indicated)
🔹 Postrenal AKI
Catheterization
Stenting / surgery
Stone management
Indications for Dialysis (AEIOU)
Acidosis (refractory)
Electrolyte imbalance (severe hyperkalemia)
Intoxication
Overload (pulmonary edema)
Uremia (encephalopathy, pericarditis)
Prognosis
Excellent if detected early
Delayed treatment → CKD risk
Recurrent AKI episodes increase long-term kidney damage
Prevention (Key Message for Patients)
Adequate hydration
Avoid unnecessary painkillers (NSAIDs)
Regular monitoring in diabetics & hypertensives
Early hospital visit during fever, vomiting, diarrhea, or low urine output
Clinical Take-Home Message
Acute Kidney Injury is often reversible—time is kidney. Early diagnosis, prompt intervention, and expert monitoring can save both kidneys and lives.
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