The nurse believes a patient is experiencing prerenal dysfunction and not intrinsic renal failure because of which laboratory finding?

Question

1. Urine osmolality of 200 mOsm/L
2. Urine osmolality of 550 mOsm/L
3. Urine sodium greater than 40 mmol/L
4. Presence of granular casts and sediment

Answer 1

2
Rationale 1: This laboratory value indicates intrinsic renal failure because the osmolality is less than 350 mOsm/L.
Rationale 2: In prerenal dysfunction, the urinalysis typically shows a concentrated urine with a high osmolality (500 mOsm/L) and a decreased urine sodium (<20 mmol/L).
Rationale 3: This laboratory value indicates instrinsic renal failure because the urine sodium is greater than 40 mmol/L.
Rationale 4: A fractional excretion of sodium (FENa) greater than 1% with granular casts and sediment is seen in intrinsic renal failure.