Final answer:
In a case of ischemic acute tubular necrosis, a nurse would anticipate decreased urinary osmolality, as the damaged tubules in the kidneys would be unable to concentrate urine effectively. So the correct answer is Option D.
Step-by-step explanation:
A client with significant burns on his lower body has developed sepsis on the third day following his accident. A nurse would anticipate decreased urinary osmolality for an ischemic acute tubular necrosis (ATN) rather than prerenal failure. Unlike prerenal azotemia, which is characterized by increased reabsorption and therefore higher osmolality due to the body's attempt to conserve water, ATN is associated with tubular damage. This damage impairs the kidney's ability to concentrate urine, leading to a lower urinary osmolality. Other characteristics of ATN may include an increased urine output due to the inability of the damaged tubules to reabsorb water, as well as a non-responsiveness to diuretic agents.