Urine to Plasma Osmolar Ratio and Pre-renal Oliguria.

a) A Uosm : Posm ratio > 1.5 indicates post-renal oliguria.

b) Pre-renal oliguria is generally due to hyperhydration.

c) Uosm : Posm ratio is unrelated to renal function.

d) A Uosm : Posm ratio > 1.5 suggests pre-renal oliguria.