Final answer:
The most concerning laboratory result for a patient with AKI is a potassium level of 5.9 mEq/L, indicating hyperkalemia, which can be life-threatening.
Step-by-step explanation:
For a patient with Acute Kidney Injury (AKI), the laboratory result that would cause the greatest concern is A. Potassium level of 5.9 mEq/L. This is considered hyperkalemia, which is a high level of potassium in the blood that can lead to dangerous heart rhythms and cardiac arrest. In comparison, a BUN level of 25 mg/dL is elevated but not immediately life-threatening. A sodium level of 144 mEq/L is within normal range, and a pH of 7.5, while indicating mild alkalosis, isn't as immediately dangerous as severe hyperkalemia. Hyperkalemia, or high potassium levels, can be life-threatening and can cause cardiac arrhythmias. Therefore, a high potassium level would be the most concerning laboratory result for a patient with AKI.