<prompt> Which differentiating prerenal azotemia with ATN features oring pre-renal azotemia -Urine osmolality 500 mosmolkgSodium spot excretion 10 mlLPlasma transferrinIg ratioAll the above  <response>: The normal kidney can elaborate urine with a maximum concentration greater than 1,200 mOsmkg in states of dehydration. A urinary osmolality Uosm greater than 500 mOsmkg,, is highly suggestive of prerenal azotemia Ref Harrison20th edition pg ,299 