Why Vitamin B12 Deficiency Should be on your Radar Screen

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<strong>Vitamin</strong> <strong>B12</strong> <strong>Deficiency</strong> Manifestations of Low <strong>Vitamin</strong> <strong>B12</strong> Levels “Although some clinical expressions remain mysterious, especially the neurological dysfunction, our view of cobalamin deficiency has expanded <strong>be</strong>yond the question of megaloblastic anemia.” Carmel, 2000 No single symptom, or cluster of symptoms, has <strong>be</strong>en uniquely associated with inadequate levels of vitamin <strong>B12</strong>. Among older adults, the most frequently reported symptoms of vitamin <strong>B12</strong> deficiency are hematologic or neurologic in nature, but gastrointestinal and possibly vascular symptoms are also common. The typically nonspecific manifestations of a vitamin <strong>B12</strong> deficiency underscore the importance of encouraging all older adults to consume the synthetic form of the vitamin each day. Recent concerns have also <strong>be</strong>en raised about potential adverse effects on infant growth and development in exclusively breastfed babies of mothers who adhere to a strict vegan diet.(11, 16) While this situation is rare in the United States, sequelae are often severe and irreversible in these children. Hematologic Manifestations Common symptoms associated with hematologic pathology include skin pallor, weakness, fatigue, syncope, shortness of breath, and palpitations.(2, 10) A classic hematologic sign of severe vitamin <strong>B12</strong> deficiency is megaloblastic anemia.(2) Hematologic manifestations might also <strong>be</strong> due to folate deficiency. However, since 1998, the U.S. Food and Drug Administration has required fortification of all enriched grain and cereal products with 140 micrograms (µg) of folic acid per 100 grams of cereal grain product,(37) and that fortification of the U.S. food supply essentially has eliminated the prevalence of folate deficiency.(21) Today, in the United States, a case of megaloblastic anemia most likely is due to vitamin <strong>B12</strong> deficiency until proven otherwise. Although vitamin <strong>B12</strong> deficiency is not always accompanied by hematologic changes, the majority of 23 Today, in the United States, megaloblastic anemia is most likely due to a vitamin <strong>B12</strong> deficiency until proven otherwise. Folic acid fortification does not have an effect on the prevalence of megaloblastic anemia attributable to vitamin <strong>B12</strong> deficiency. Very high doses of folic acid (>5,000 µg each day) can correct the hematologic manifestations of vitamin <strong>B12</strong> deficiency; however, the amount of folic acid available through fortification as specified by the U.S. Food and Drug Administration (FDA) is not likely to affect a vitamin <strong>B12</strong> deficiency-induced anemia (FDA, 1996).
<strong>Vitamin</strong> <strong>B12</strong> <strong>Deficiency</strong> patients with clinical deficiency will have signs of megaloblastic anemia. In various studies conducted among patients with overt vitamin <strong>B12</strong> deficiency, 56%– 77% of people had signs of macrocytosis or anemia.(5, 38-41) Furthermore, some researchers have found that the presence of neurologic manifestations of a vitamin <strong>B12</strong> deficiency might even <strong>be</strong> correlated inversely with evidence of hematologic effects.(10, 39, 42) Neurologic Manifestations Common neurologic complaints include paresthesias (with or without objective signs of neuropathy), weakness, motor disturbances (including gait abnormalities), vision loss, and a wide range of cognitive and <strong>be</strong>havioral changes (e.g., dementia, hallucinations, psychosis, paranoia, depression, violent <strong>be</strong>havior, and personality changes). Tingling of the hands and feet is perhaps the most common neurologic complaint.(2, 41, 42) The pathology of vitamin <strong>B12</strong> deficiency on the nervous system is unknown.(7) All patients with unexplained cognitive decline or dementia should <strong>be</strong> assessed for a possible vitamin <strong>B12</strong> deficiency.(41, 43-45) Several current case reports and studies support the common practice of assessing vitamin <strong>B12</strong> levels during dementia workups.(41, 46-48) Although only a minority (1.5%) of all dementia cases are fully reversible following treatment,(49) many dementias from other etiologies (e.g., Parkinson or Alzheimer disease) are exacerbated when patients have a concomitant low vitamin <strong>B12</strong> level. The American Academy of Neurology (AAN) has concluded that <strong>be</strong>cause vitamin <strong>B12</strong> deficiency is a likely comorbidity among the elderly, and among patients with suspected dementia in particular, it should <strong>be</strong> recognized and treated. The AAN practice guideline states that <strong>B12</strong> levels should <strong>be</strong> included in routine assessments of dementia among the elderly.(44) 24 Many <strong>B12</strong>–deficient patients do have anemia or macrocytosis. All patients newly diagnosed with unexplained cognitive decline or dementia should <strong>be</strong> assessed for a possible vitamin <strong>B12</strong> deficiency.
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Why Vitamin B12 Deficiency Should be on your Radar Screen

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