What laboratory finding is expected in a patient with acute renal failure?

In a patient with acute renal failure, one would expect to see increased levels of blood urea nitrogen (BUN) as a key laboratory finding. This is primarily due to the kidneys' reduced ability to filter waste products from the blood. When renal function declines, the accumulation of nitrogenous waste, which includes urea, leads to elevated BUN levels. This serves as an important marker in assessing kidney function and the severity of renal impairment.

In contrast, while urine output can vary in renal failure, it is often decreased or absent; hence, increased urine output would not typically be seen. Similarly, creatinine levels would generally rise, not decrease, in the context of renal failure. Normal electrolyte levels are also unlikely, as renal failure often disrupts the body's ability to maintain electrolyte homeostasis, leading to imbalances. Therefore, increased blood urea nitrogen is the expected finding in acute renal failure, signifying impaired kidney function.