Table 11.1-4. Selected differential features of prerenal azotemia and intrinsic AKI


Prerenal AKI

Intrinsic AKI

Daily urine output (mL)



Urine osmolality (mOsm/kg H2O)



Urine specific gravity (g/mL)



Ratio of urea (mmol/L) to serum creatinine (micromol/L)



Ratio of urinary to serum creatinine concentration



Urinary [Na+] concentration (mmol/L)a



Fractional excretion of sodiumb



Urine sediment

No abnormal findings or hyaline casts only

Epithelial cells, pigmented muddy-brown granular casts or tubular epithelial cell casts

a Urinary sodium concentration (this should be measured before administering furosemide).

b Fractional excretion of sodium: FENa = [(urinary Na concentration in mmol/L × serum creatinine concentration in mg/dL) / (serum Na concentration in mmol/L × urinary creatinine concentration in mg/dL)] × 100%.

AKI, acute kidney injury.