A nurse is monitoring an older adult female client who had a myocardial infarction (MI) for the development of an acute kidney injury. Which of the following findings should the nurse identify as indicating an increased risk of acute kidney injury (AKI)?

Choice A rationale The normal range for serum creatinine is approximately 0.6 to 1.2 mg/dL for adults. A value of 2.1 mg/dL is significantly elevated, indicating a reduction in the glomerular filtration rate and impaired renal function. In the context of a myocardial infarction, low cardiac output can lead to pre-renal azotemia or acute tubular necrosis. This elevation serves as a primary marker for the development of acute kidney injury, reflecting the kidneys' inability to clear metabolic waste effectively. Choice B rationale Serum osmolality represents the concentration of particles dissolved in the blood, with a normal range typically between 275 and 295 mOsm/kg H2O. A value of 290 mOsm/kg H2O is within the normal physiological limits. This indicates a stable balance of electrolytes and water in the plasma. Since the value is normal, it does not suggest an increased risk or current state of acute kidney injury or fluid volume disturbances that would damage renal tissue. Choice C rationale The normal range for serum magnesium is approximately 1.3 to 2.1 mEq/L. A magnesium level of 2.0 mEq/L is within the normal therapeutic range. While electrolyte imbalances can occur during renal failure, a normal magnesium level does not indicate an increased risk of acute kidney injury. Magnesium is primarily excreted by the kidneys, so while its level might rise if injury occurs, the current value of 2.0 mEq/L indicates that renal clearance is currently sufficient. Choice D rationale The normal range for blood urea nitrogen (BUN) is typically 10 to 20 mg/dL. A BUN of 20 mg/dL is at the upper limit of the normal range but is not considered an elevated finding that signifies acute kidney injury on its own. BUN can be influenced by protein intake, hydration status, and liver function. Without an accompanying elevation in creatinine, this normal BUN level does not suggest that the patient is at high risk for kidney failure.