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Causes and pathophysiology of vitamin B12 and folate deficiencies

Stanley L Schrier, MD
Section Editor
Kathleen J Motil, MD, PhD
Deputy Editor
Jennifer S Tirnauer, MD


Deficiencies of vitamin B12 and/or folate can cause megaloblastic anemia (macrocytic anemia with other features due to impaired cell division). Vitamin B12 deficiency can also cause neuropsychiatric findings. In addition to correcting the deficiency, an important aspect of management is determining the underlying cause because the need for additional testing, the duration of therapy, and the route of administration may differ depending on the underlying cause.

This topic review discusses the major causes of vitamin B12 and folate deficiency, along with their pathophysiology.

Separate topic reviews discuss the clinical presentation, diagnosis, and treatment of these deficiencies:

Clinical presentation and diagnosis – (See "Clinical manifestations and diagnosis of vitamin B12 and folate deficiency".)

Treatment – (See "Treatment of vitamin B12 and folate deficiencies".)

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Literature review current through: Nov 2017. | This topic last updated: Sep 20, 2017.
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