A nurse is caring for a 32-year-old client with a history of peptic ulcer disease who has been taking omeprazole 40 mg daily for the past 6 months. The client reports recently feeling weak and fatigued. Based on the client's medication history and symptoms, which assessment is most appropriate for the nurse to perform?

Long-term PPI therapy impairs vitamin B12 absorption, leading to deficiency and symptoms like weakness and fatigue. The nurse should assess for signs of megaloblastic anemia and neurological symptoms. Other options are less directly related to the client's presentation.

Understanding the Clinical Scenario
A 32-year-old client with a history of peptic ulcer disease has been on long-term omeprazole therapy at 40 mg daily for 6 months. The client's new report of weakness and fatigue, in the context of this medication history, should immediately prompt the nurse to consider adverse effects related to chronic acid suppression.

Why Long-Term PPI Use Leads to Nutrient Deficiency
The primary mechanism involves the profound reduction of gastric acid secretion by proton pump inhibitors (PPIs) like omeprazole. Gastric acid is essential for the release of vitamin B12 from food proteins. Without adequate acid, pepsin cannot cleave B12 from its dietary protein carriers, preventing it from binding to R-proteins and later to intrinsic factor for absorption in the terminal ileum. This process, when disrupted over months, depletes hepatic stores and leads to a functional vitamin B12 deficiency [1,2].

Connecting Pathophysiology to the Client's Symptoms
The symptoms reported—weakness and fatigue—are classic, nonspecific manifestations of anemia. In the context of prolonged PPI use, the most likely etiology is a developing megaloblastic anemia secondary to vitamin B12 deficiency. The deficiency impairs DNA synthesis in erythrocyte precursors within the bone marrow, leading to large, immature, and often destroyed red blood cells. This results in decreased oxygen-carrying capacity, which the client perceives as fatigue and weakness. While PPIs can also impair the absorption of iron, magnesium, and calcium, the constellation of a 6-month history and generalized fatigue points most directly toward a B12-related process [1,3].

Analysis of the Answer Choices
The nurse must prioritize an assessment that directly correlates with the highest risk associated with the specific medication history.

- Option 1: Monitor for signs of gastric bleeding and melena. While a history of peptic ulcer disease carries a baseline risk for bleeding, the client is on a therapeutic dose of a PPI, which is the primary treatment to prevent ulcer recurrence and bleeding. There are no new symptoms (e.g., epigastric pain, black tarry stools) to suggest an active bleed. This assessment does not address the most likely cause of the new-onset fatigue related to the medication itself.
- Option 2: Assess for drug interactions with warfarin therapy. The scenario provides no information suggesting the client is on warfarin. This assessment is not indicated based on the available data and represents a distraction from the client's actual reported symptoms and medication history.
- Option 3: Evaluate compliance with dietary restrictions. While dietary modifications are a component of peptic ulcer disease management, non-compliance would more likely trigger dyspepsia or pain, not isolated fatigue and weakness. This option ignores the direct physiological consequence of the medication.
- Option 4: Monitor for signs of vitamin B12 deficiency and anemia. This is the most appropriate assessment. The client has a clear risk factor (chronic PPI use for ≥6 months) and presents with hallmark symptoms of anemia (weakness, fatigue). A focused assessment would include checking for other signs like pallor, glossitis, and peripheral neuropathy, and anticipating laboratory evaluations such as a complete blood count (CBC) and serum B12 levels [1,2]. A retrospective study found that chronic acid blockade with PPIs is significantly associated with clinically relevant micronutrient deficiencies, including vitamin B12, due to reduced absorption ^[1]. A separate pharmacovigilance analysis confirmed a significant signal for vitamin B12 deficiency associated with PPI use in a real-world database ^[2].