The nurse is reviewing laboratory results for a group of patients. Which value should be of most concern to the nurse?

A. Sodium level of 140 mEq/L is within the normal range, indicating proper fluid and electrolyte balance; no immediate intervention is needed. B. Magnesium level of 1.0 mEq/L is below the normal range and indicates significant hypomagnesemia. Low magnesium can cause neuromuscular irritability, tetany, tremors, seizures, cardiac dysrhythmias, and can contribute to hypokalemia and hypocalcemia, making it the most concerning value. C. Potassium level of 3.5 mEq/L is at the lower limit of normal. While it should be monitored to prevent hypokalemia, it is not immediately dangerous unless it decreases further or the patient develops cardiac risk factors. D. Calcium level of 10 mg/dL is within the normal range, suggesting normal neuromuscular and skeletal function. No immediate intervention is required.