Dtsch Arztebl Int
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Vitamin B(12) deficiency is widespread. Among the population groups at risk are older people, vegetarians, pregnant women, and patients with renal or intestinal diseases. The neurological symptoms of vitamin B(12) deficiency are unspecific and can be irreversible. Early detection is therefore important, using the most sensitive and specific markers available. ⋯ Total serum vitamin B(12) is a late, relatively insensitive and unspecific biomarker of deficiency. Holotranscobalamin (holoTC), also known as active B(12), is the earliest laboratory parameter for B(12) deficiency, while methyl malonic acid (MMA) is a functional B(12) marker that will increase when the B(12) stores are depleted. Isolated lowering of holoTC shows B(12) depletion (negative B(12) balance), while lowered holoTC plus elevated MMA and homocysteine indicates a metabolically manifest B(12) deficiency, although there still may be no clinical symptoms. The diagnostic use of holoTC allows treatment to be instituted before irreversible neurological damage occurs. As the first clinical manifestations of vitamin B(12) deficiency are unspecific, those at risk should have their B(12) status checked regularly, every two to three years. Because no randomized controlled trials have yet been completed, the diagnostic and therapeutic measures proposed here are merely recommendations.
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10% to 20% of the population sees itself as suffering from food allergy, yet genuine, immune-mediated food allergy is suspected by patients and their physicians far more often than it is actually shown to be present. The unfounded suspicion of an IgE-mediated food allergy can substantially impair a patient's quality of life through needless dietary restriction and the accompanying anxiety. On the other hand, an IgE-mediated food allergy that has gone undiagnosed or that has not been taken seriously can manifest suddenly with anaphylaxis, which may be life-threatening. The present study, carried out on a large cohort of patients, underscores the importance of differentiating IgE-mediated food allergy from other, nonallergic types of food reaction. ⋯ Only a comprehensive allergological evaluation performed by an experienced allergologist in accordance with current guidelines can protect patients from the negative consequences of excessive concern about a nonexistent food allergy (e.g., needless dietary restriction) or, on the other hand, the negative consequences of inadequate attention to a genuine food allergy (anaphylaxis). A proper evaluation consists of detailed allergologic history-taking, skin tests, and challenge tests when indicated.