A client is currently prescribed pantoprazole, and the nurse is reviewing the client's labs (shown below). Which lab result is of most concern to the nurse? Laboratory Test Result Normal Range Sodium 146 mEq/dL 135-145 mEq/L Calcium 8.2 mg/dL 8.4-10.2 mg/dL Magnesium 1.2 mg/dL 1.6-2.2 mg/dL Gastric pH 6 1-4

A. Sodium: Sodium levels are important to monitor, but in the context of pantoprazole use, abnormal sodium levels are less commonly a direct concern. Pantoprazole primarily impacts the gastric environment rather than fluid or electrolyte balance in a way that would dramatically alter sodium levels. B. Gastric pH: Pantoprazole works to increase gastric pH by reducing acid secretion, which is its primary therapeutic effect. A higher gastric pH is expected and beneficial in conditions like GERD or peptic ulcers. C. Calcium: Pantoprazole, when used for extended periods, can interfere with calcium absorption, potentially leading to bone health issues like osteoporosis. However, changes in calcium levels typically do not pose an immediate or life-threatening concern unless significantly low or related to prolonged therapy. It is still something to monitor, but magnesium is a higher priority in this case. D. Magnesium: Pantoprazole and other proton pump inhibitors (PPIs) are known to cause hypomagnesemia, especially with prolonged use. Low magnesium levels can lead to serious complications, including muscle spasms, seizures, and arrhythmias. Hypomagnesemia is a well-documented side effect of long-term PPI use, making it the most critical lab result to address.