What is the significance of a low Vitamin B-12 (cobalamin) level of 174 picograms per milliliter (pg/mL) in a 22-year-old female with no past medical history (PMH)?

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Last updated: May 22, 2025View editorial policy

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From the Guidelines

The patient with a vitamin B12 level of 174 pcg/mL should be treated immediately with hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2–3 months for life, as per the guidelines from the British Obesity and Metabolic Surgery Society 1. The patient's vitamin B12 level is below the reference range, indicating a deficiency that requires prompt treatment to prevent potential complications such as megaloblastic anemia, neurological involvement, and other systemic issues. According to the guidelines, for people with no neurological involvement, hydroxocobalamin 1 mg intramuscularly should be administered three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2–3 months for life 1. It is essential to note that folic acid should not be given first, as it may mask underlying vitamin B12 deficiency and precipitate subacute combined degeneration of the spinal cord 1. Additionally, the patient should be advised to increase dietary intake of B12-rich foods like meat, fish, eggs, and dairy products. Investigating the underlying cause of B12 deficiency is also crucial, which could include inadequate dietary intake, malabsorption disorders, certain medications, or increased requirements during pregnancy. Recent studies have highlighted the importance of treating vitamin B12 deficiency, especially in patients with stroke, as it can help reduce the risk of stroke and other cardiovascular events 1. Therefore, prompt treatment of vitamin B12 deficiency is essential to prevent potential complications and improve patient outcomes. Key points to consider in the treatment of vitamin B12 deficiency include:

  • Immediate treatment with hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2–3 months for life
  • Avoiding folic acid supplementation until vitamin B12 deficiency is treated
  • Increasing dietary intake of B12-rich foods
  • Investigating the underlying cause of B12 deficiency
  • Monitoring patient response to treatment and adjusting as necessary.

From the Research

Vitamin B12 Deficiency Diagnosis and Treatment

  • The patient's vitamin B12 level is 174 pcg/mL, which is below the reference range of 180-914 pcg/mL, indicating a deficiency 2.
  • Vitamin B12 deficiency can cause various symptoms, including megaloblastic anemia, neuropsychiatric symptoms, and other clinical manifestations 3.
  • Diagnosis of vitamin B12 deficiency can be challenging due to diverse symptoms and limitations of laboratory tests, such as serum B12, methylmalonic acid, and homocysteine levels 4.

Treatment Options

  • Oral administration of high-dose vitamin B12 (1-2 mg daily) can be as effective as intramuscular administration for correcting anemia and neurologic symptoms 3.
  • Intramuscular therapy may be preferred for patients with severe deficiency or severe neurologic symptoms, and can lead to more rapid improvement 3.
  • Parenteral supplementation (e.g., 1000 µg intramuscular hydroxocobalamin once every two months) may be necessary for patients with malabsorption 2.
  • High-dose oral B12 at different frequencies may be considered for long-term treatment 5.

Patient-Specific Considerations

  • Patient lifestyle, disease history, and medications can provide clues to the cause of B12 deficiency 5.
  • Prophylactic B12 supplementation should be considered for specific high-risk groups, such as vegans or strict vegetarians, and patients with gastric or small intestine resections 3, 6.
  • Clinical symptoms should receive the highest priority in establishing the diagnosis of B12 deficiency, and laboratory markers can support the diagnosis 5.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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