A patient on long-term lansoprazole presents with fatigue, muscle tremors and spasms. Which electrolyte abnormality is most likely the cause?

• A. Hypermagnesemia
• B. Hypomagnesemia
• C. Hyperkalemia
• D. Hyponatremia

Answer: (B)

Long-term proton pump inhibitor use can reduce magnesium absorption in the gut, leading to hypomagnesemia. Magnesium is essential for stabilizing neuromuscular activity, so when levels fall, nerves and muscles become irritable, producing fatigue, tremors, cramps or spasms, and sometimes more severe neuromuscular symptoms. In this patient, the combination of chronic lansoprazole and muscle-related symptoms fits hypomagnesemia best. Hypermagnesemia would more likely cause decreased reflexes and hypotension; hyperkalemia and hyponatremia have different symptom profiles and don’t typically present with this neuromuscular irritability pattern.