# A nurse is caring for a 65-year-old client diagnosed with vitamin B12 deficiency anemia who presents with fatigue, weakness, and tingling in hands and feet. Laboratory results show a B12 level of 150 pg/mL (normal: 200-900 pg/mL). Which nursing intervention should the nurse prioritize?

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> subject: Adult Health

## 문제

A nurse is caring for a 65-year-old client diagnosed with vitamin B12 deficiency anemia who presents with fatigue, weakness, and tingling in hands and feet. Laboratory results show a B12 level of 150 pg/mL (normal: 200-900 pg/mL). Which nursing intervention should the nurse prioritize?

## 보기

1. Encourage increased intake of iron-rich foods such as red meat and spinach
2. Administer vitamin B12 injections **✔ 정답**
3. Provide supplemental oxygen therapy
4. Restrict dietary intake of folic acid to prevent masking of symptoms

**정답: 2**

## 해설

Vitamin B12 injections are the most effective treatment for vitamin B12 deficiency anemia, especially when deficiency is severe or caused by malabsorption issues. Vitamin B12 deficiency anemia is a serious condition requiring immediate and appropriate intervention. The priority nursing intervention is to administer prescribed vitamin B12 injections, as this directly and immediately replenishes the deficient vitamin. Vitamin B12 (cobalamin) is essential for DNA synthesis, red blood cell formation, and proper neurological function. When deficiency occurs, megaloblastic anemia develops, characterized by large, immature red blood cells that cannot effectively carry oxygen. Neurological symptoms such as tingling in the hands and feet (peripheral neuropathy) occur due to demyelination of nerve fibers. Injectable vitamin B12 is the standard of care because it bypasses potential absorption issues in the gastrointestinal tract. Many cases of B12 deficiency result from malabsorption disorders such as pernicious anemia (lack of intrinsic factor), gastric surgery, or inflammatory bowel disease. In these cases, oral supplements may not be effective. The typical treatment protocol involves initial high-dose injections (usually 1000 mcg intramuscularly) given daily or weekly for several weeks, followed by monthly maintenance injections. This approach rapidly corrects the deficiency and prevents progression of neurological complications, which can become irreversible if left untreated. Early intervention with B12 injections can reverse many symptoms, including fatigue, weakness, and early neurological symptoms, making it the most critical nursing intervention for optimal patient outcomes.

Analysis of incorrect options:
- Option 1: Recommending iron-rich foods is appropriate for iron deficiency anemia but does not address the underlying cause of B12 deficiency anemia.
- Option 3: Supplemental oxygen therapy may alleviate hypoxia but does not treat the B12 deficiency itself.
- Option 4: Limiting folic acid intake may mask B12 deficiency symptoms but does not correct the deficiency and can actually worsen it.

## 심화 해설

Understanding the Priority

The client presents with classic signs of vitamin B12 deficiency: hematologic symptoms (fatigue, weakness) and neurologic symptoms (tingling in hands and feet, indicating peripheral neuropathy). The lab value of 150 pg/mL confirms the deficiency, as it falls below the normal range of 200-900 pg/mL. The priority is to correct the underlying deficiency to prevent the progression of irreversible neurologic damage.

Why Option 2 is Correct

Administering vitamin B12 injections is the definitive treatment to replenish depleted body stores and reverse the pathophysiological processes. Cobalamin (vitamin B12) is crucial for DNA synthesis, fatty acid metabolism, and myelin production [2]. A deficiency disrupts myelin synthesis, leading to the neurologic symptoms of peripheral neuropathy the client is experiencing. Prompt replacement via injection is prioritized to halt and reverse this neurologic deterioration, as prolonged myelin damage can become permanent [2]. For clients with significant neurologic involvement, parenteral administration ensures high bioavailability, bypassing any potential issues with absorption in the gastrointestinal tract.

Analysis of Incorrect Options

**Option 1:** Encouraging increased intake of iron-rich foods is the primary intervention for iron deficiency anemia, not vitamin B12 deficiency anemia. While dietary sources like red meat do contain B12, a client with a symptomatic, confirmed deficiency and neurologic symptoms requires pharmacologic replacement. Furthermore, the most common cause of B12 deficiency is malabsorption (e.g., pernicious anemia), not inadequate dietary intake, making oral intake an ineffective initial priority .

**Option 3:** Providing supplemental oxygen therapy is a supportive measure for general anemia when tissue hypoxia is evident (e.g., severe dyspnea, low SpO2). However, it does not address the root cause of the anemia or the neurologic symptoms. The priority is to treat the specific deficiency causing the condition.

**Option 4:** Restricting dietary intake of folic acid is contraindicated. While high doses of folic acid can partially correct the hematologic abnormalities of B12 deficiency, they do not halt the progression of neurologic damage. This "masking" of symptoms is a known phenomenon, but the clinical response is to ensure adequate B12 levels, not to restrict folate. Restricting folate could lead to a separate deficiency and does nothing to treat the underlying B12 deficiency and its neurologic effects.References (research sources)

- [2]B Vitamin Deficiencies and Associated Neuropathies.Research articleAlvarez M, Poveda S, Cisneros A, Parra D, Luna M, Rincón O, Guzman I. (2026) · DOI: 10.1007/s13668-025-00723-3

## 임상 시나리오

Managing B12 Deficiency with Neurologic SymptomsPrioritizing Parenteral Replacement to Prevent Permanent Damage
For a client with confirmed vitamin B12 deficiency and neurologic symptoms like peripheral neuropathy, the priority is immediate parenteral B12 administration (intramuscular or deep subcutaneous injection). This bypasses any potential GI absorption issues and delivers a high concentration directly to the tissues.

The goal is to halt the progression of demyelination. Neurologic damage from prolonged B12 deficiency can become irreversible if not treated promptly. A standard regimen often begins with intensive injections (e.g., 1000 mcg daily or weekly) before transitioning to a maintenance schedule.

CautionDo not delay treatment by focusing on dietary changes or oral supplements in symptomatic patients with neurologic involvement. Monitor for hypokalemia during the initial phase of treatment, as rapid cell production can cause a drop in serum potassium.

## 핵심 개념

- **Peripheral Neuropathy** — Damage to the peripheral nerves, often causing weakness, numbness, and pain, usually in the hands and feet; a common neurologic complication of vitamin B12 deficiency due to impaired myelin synthesis.
- **Cobalamin** — Another name for vitamin B12, a water-soluble vitamin essential for DNA synthesis, red blood cell formation, and neurological function.
- **Parenteral Administration** — A route of medication administration that bypasses the gastrointestinal tract, typically via injection (intramuscular or subcutaneous), ensuring high bioavailability when absorption is impaired.
- **Myelin Synthesis** — The process of forming the myelin sheath, a protective covering around nerve fibers that ensures rapid and efficient transmission of nerve impulses; disrupted in B12 deficiency.

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