People with mild anemia may have no symptoms, or symptoms may be very mild.

More typical symptoms of vitamin B12 deficiency anemia include:

• Diarrhea or constipation
• Fatigue, lack of energy, or light-headedness when standing up or with exertion
• Loss of appetite
• Pale skin
• Problems concentrating
• Shortness of breath, mostly during exercise
• Swollen, red tongue or bleeding gums

Symptoms from nerve damage caused by vitamin B12 deficiency that has been present for a longer time include:

• Confusion or change in mental status (dementia) in severe cases
• Depression
• Loss of balance
• Numbness and tingling of hands and feet

A physical exam may show problems with reflexes or a positive Babinski reflex.

The following tests may be done:

• CBC
• Reticulocyte count
• Schilling test (if pernicious anemia is suspected)
• Serum LDH
• Serum vitamin B12 level and serum folate levels

Esophagogastroduodenoscopy (EGD) to examine the stomach, or enteroscopy to examine the small intestine may be done.

Bone marrow biopsy is done only when the diagnosis is not clear.