AKI vs CKD

Differentiating Acute Kidney Injury from Chronic Kidney Disease.

Key Differentiating Features
ParameterAKI (Acute)CKD (Chronic)
HistoryRecent onset (< 7 days)Longstanding (> 3 months)
Previous CreatinineNormal or lower baselineElevated baseline
Kidney Size (Ultrasound)Normal (10-12 cm) or EnlargedSmall (< 9 cm) & Echogenic
HemoglobinUsually NormalAnemia (Low EPO)
PTH (Parathyroid Hormone)NormalElevated (Secondary Hyperparathyroidism)
Bone DiseaseAbsentRenal Osteodystrophy
NeuropathyAbsentPeripheral Neuropathy often present
Ultrasound Clues

CKD Findings:

  • Small size (< 9 cm)
  • Increased cortical echogenicity (brighter than liver)
  • Cortical thinning (< 10 mm)
  • Loss of corticomedullary differentiation
Exceptions (Large Kidneys in CKD): Diabetic Nephropathy, HIV Nephropathy, Amyloidosis, Polycystic Kidney Disease.
Acute on Chronic

Patients with CKD are at higher risk for AKI. Diagnosis relies on:

  • 1Clear rise in Cr from baseline
  • 2New onset oliguria
  • 3New active sediment (casts, RBCs)

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Disclaimer: Educational tool only. Not a substitute for professional medical judgment. Verify all information independently.