Vitamin B12 Deficiency

Sahil Mullick, MD and Maisam T Begum, MD Reviewed 06/2022

BASICS

Vitamin deficiency related to inadequate intake or absorption of cobalamin (vitamin B₁₂)
Cobalamin is critical for central nervous system myelination, red blood cell production, and DNA synthesi...

DIAGNOSIS

Symptoms and physical exam findings:

Asymptomatic patients may be diagnosed by the incidental finding of anemia or an elevated mean corpuscular volume (MCV) during routine testing or evaluat...

TREATMENT

All individuals with documented vitamin B₁₂ deficiency should be treated, unless there's a strong reason not to such as patient refusal or palliative care setting.

GENERAL MEASURES

Repleting ...

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

Hematologic
- Reticulocytosis in 1 week
- Hemoglobin will usually return to normal in 6 to 8 weeks
- Monitor potassium in profoundly anemic patients (hyp...

REFERENCES

Lee SM, Oh J, Chun MR, Lee SY. Methylmalonic Acid and Homocysteine as Indicators of Vitamin B12 Deficiency in Patients with Gastric Cancer after Gastrectomy. Nutrients. 2019 Feb 21;11(2):4...

CODES

ICD10

D51 Vitamin B12 deficiency anemia
D51.3 Other dietary vitamin B12 deficiency anemia
D51.8 Other vitamin B12 deficiency anemias
D51.9 Vitamin B12 deficiency anemia, unspecified
E53.8 Deficiency ...

CLINICAL PEARLS

Vitamin B₁₂ deficiency can coexist with other anemia; thus, MCV can be normal, decreased, or increased.
For PA, cyanocobalamin must be lifelong.

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