Final answer:
The nurse should be most concerned with the low sodium level of 125 mEq/L, which requires immediate intervention to prevent complications.
Step-by-step explanation:
The nurse should be most concerned with the sodium level of the client, which is 125 mEq/L. Sodium plays a critical role in maintaining fluid balance and nerve function in the body. A low sodium level, known as hyponatremia, can lead to symptoms such as confusion, seizures, and even coma if left untreated. In this case, the low sodium level requires immediate intervention to prevent further complications.
The potassium level of 3.9 mEq/dL is within the normal range (3.5-5.0 mEq/dL). A slightly elevated creatinine level of 1.1 mg/dL and a slightly decreased calcium level of 9 mg/dL may indicate kidney dysfunction or bone issues, but they are not immediate concerns compared to the low sodium level.