Acute Kidney Injury - AKI Workup Algorithm and Differential Diagnosis

Baseline Investigations: full blood count with differential, urine dipstick, urine microscopy / urinary sediment, renal ultrasonography, serum calcium

Optional: urinary electrolytes, urea, uric acid, osmolarity

If cause of AKI remains unclear AND hypovolaemia and obstruction excluded OR any of the above investigations abnormal: consider the following investigations depending on clinical context and signs

 • Glomerulonephritis / Vasculits: ANCA, ANA, Anti-GBM, Anti-ds-DNA, C3/C4, ENA, immunoglobulins, cryoglobulins, hepatitis serology, HIV serology, renal biopsy

 • Interstitial nephritis: eosinophilia, eosinophiluria, renal biopsy

 • Abdominal compartment syndrome: intravesicular pressure

 • TTP / HUS: fragmentocytes, LDH, platelets, reticulocytes, haptoglobin, bilirubin

 • Rhabdo-myolysis: CK, myoglobin

 • Myeloma: serum / urine, protein-electrophoresis, renal biopsy

 • Sepsis: sepsis screen, including blood culture, urine culture, inflammatory markers

 • Cardio-renal syndrome: troponin, CK-MB, NT-proBNP, cardiac imaging



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