From the Guidelines
The most appropriate next step in management for this 72-year-old woman is intramuscular injections of vitamin B12 (cyanocobalamin). The patient presents with progressive balance difficulties, unsteady gait, and numbness in her legs, which are classic neurological manifestations of vitamin B12 deficiency. Her laboratory results confirm this diagnosis with a significantly low vitamin B12 level of 100 pg/mL (normal range 160-950 pg/mL) 1. She also has a mild anemia with hemoglobin of 11 g/dL, which is consistent with the hematologic effects of B12 deficiency.
Key Considerations
- The patient's symptoms, such as unsteady gait and numbness in her legs, suggest neurological involvement, which requires immediate treatment of vitamin B12 deficiency 1.
- Intramuscular administration is necessary because vitamin B12 deficiency in older adults is typically caused by pernicious anemia (an autoimmune condition affecting intrinsic factor) or atrophic gastritis, both of which impair oral absorption of B12.
- The injections typically begin with a loading dose, followed by maintenance doses, which allows for rapid replenishment of B12 stores and prevents irreversible neurological damage 1.
Treatment Approach
- According to the British Obesity and Metabolic Surgery Society guidelines, for patients with vitamin B12 deficiency and possible neurological involvement, hydroxocobalamin 1 mg intramuscularly should be administered on alternate days until there is no further improvement, then hydroxocobalamin 1 mg intramuscularly administered every 2 months 1.
- Early treatment is crucial as prolonged deficiency can lead to permanent neurological impairment, even if hematologic parameters improve.
Comparison of Options
- Options A and B, which involve increasing dietary intake of leafy green vegetables or meat and dairy products, are not sufficient to treat the patient's vitamin B12 deficiency, especially given the potential for malabsorption.
- Option C, oral administration of folic acid, may mask severe vitamin B12 depletion and is not appropriate as the initial treatment 1.
- Option E, transfusion of packed red blood cells, is not necessary at this time, as the patient's anemia is mild and can be addressed with vitamin B12 replacement therapy. The most recent and highest quality study 1 also supports the importance of proper management of vitamin B12 deficiency, although it focuses on people with malabsorption conditions.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Pernicious Anemia Parenteral vitamin B12 is the recommended treatment and will be required for the remainder of the patient's life. A dose of 100 mcg daily for 6 or 7 days should be administered by intramuscular or deep subcutaneous injection.
The most appropriate next step in management is Intramuscular injections of vitamin B12 (cyanocobalamin), as the patient has a low Vitamin B12 level (100 pg/mL) and symptoms consistent with a Vitamin B12 deficiency, such as difficulty with balance, numbness in the legs, and decreased sensation to vibration over the feet. This is consistent with the treatment recommended in the drug label for pernicious anemia or Vitamin B12 deficiency 2.
From the Research
Patient's Condition
The patient is a 72-year-old woman with a 4-month history of progressive difficulty with balance, unsteady walking, and numbness in her legs. She has a history of mild anemia and hypertension controlled with hydrochlorothiazide.
Laboratory Findings
- Hemoglobin: 11 g/dL
- Hematocrit: 34%
- Mean corpuscular volume: not specified
- Serum Na: 137 mEq/L
- K: 39 mEq/L (likely an error, normal range is 3.5-5.5 mEq/L)
- Cl-: 103 mEq/L
- HCO: not specified (likely an error, HCO3- is the correct notation)
- Urea nitrogen: 24 mg/dL (likely an error, normal range is 6-24 mg/dL, but units are usually in mg/dL for urea nitrogen, and the value seems plausible)
- Creatinine: 1.6 mg/dL (likely an error, normal range is 0.6-1.2 mg/dL for females)
- Vitamin B12 (cobalamin): 100 pg/mL (low, normal range is 160-950 pg/mL)
Appropriate Next Step in Management
Based on the patient's symptoms and laboratory findings, the most appropriate next step in management is:
- Intramuscular injections of vitamin B12 (cyanocobalamin) 3, 4, 5 The patient's low vitamin B12 level and symptoms such as numbness in the legs and decreased sensation to vibration over the feet are consistent with vitamin B12 deficiency. Intramuscular injections of vitamin B12 are a common treatment for vitamin B12 deficiency, especially in patients with severe symptoms or those who are unable to absorb vitamin B12 orally.
Alternative Options
- Increased dietary intake of meat and dairy products may help increase vitamin B12 levels, but it may not be sufficient to treat the deficiency, especially in patients with malabsorption or severe deficiency 6, 5.
- Oral administration of folic acid is not appropriate in this case, as the patient's deficiency is in vitamin B12, not folate 4, 5.
- Transfusion of packed red blood cells is not necessary, as the patient's anemia is likely related to the vitamin B12 deficiency, which can be treated with vitamin B12 supplementation 7.