CEA Nursing Practice Exam

What lab result might indicate acute tubular necrosis?

1. Trace WBCs without nitrites

2. Increased creatinine and BUN levels

3. Normal CBC and BMP results

4. High leukocyte esterase levels

The correct answer is: Increased creatinine and BUN levels

The indication of acute tubular necrosis (ATN) is primarily associated with impaired kidney function, which can lead to elevated levels of certain substances in the blood. A significant increase in creatinine and blood urea nitrogen (BUN) levels is a hallmark of kidney dysfunction, specifically pointing towards a potential intrinsic renal issue such as ATN. Creatinine is a waste product produced from muscle metabolism, and BUN is a measure of nitrogen in the blood that comes from protein metabolism. In healthy kidneys, these substances are effectively filtered out. When the kidneys are damaged—such as in acute tubular necrosis—their ability to filter these waste products diminishes, resulting in increased levels of creatinine and BUN in the blood. In contrast, trace WBCs without nitrites and high leukocyte esterase levels are more indicative of urinary tract infections or other types of inflammation rather than ATN. Normal CBC and BMP results would suggest there are no significant abnormalities, which would not align with a diagnosis of ATN, where you would expect to see both elevated creatinine and BUN. Thus, the presence of increased creatinine and BUN is the most critical laboratory finding in diagnosing acute tubular necrosis.