People with mild anemia may have no symptoms or very mild symptoms. 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
• Nerve damage caused by vitamin B12 deficiency that has been present for a longer time may cause:
  • Confusion or change in mental status (dementia) in severe or advanced cases
  • Depression
  • Loss of balance
  • Numbness and tingling of hands and feet

Tests that may used to diagnose or monitor pernicious anemia include:

• Bone marrow examination (only needed if diagnosis is unclear)
• Complete blood count (CBC)
• Measurement of serum holotranscobalamin II
• Reticulocyte count
• Schilling test
• Serum LDH
• Serum methylmalonic acid (MMA) level
• Serum vitamin B12 level

Pernicious anemia may also affect the results of the following tests:

• Bilirubin
• Cholesterol test
• Gastrin
• Leukocyte alkaline phosphatase
• Peripheral smear
• TIBC

Vitamin B12 deficiency affects the appearance of cells that form on the outer surface of the body and line inner passageways (epithelial cells). An untreated woman may have a false positive Pap smear.