Pre-renal azotemia is associated with one of the following characteristic feature :
Answer is A (Urinary Na+ < 10 mmol/litre): Prerenal azotemia is associated with a urinary sodium excretion of less than 10 mmol/L.
Urinary Na+ < 10 mmol/L
Renal failure index > 1
Osmolality < 500
Urinary creatinine / P. creatinine ratio < 20