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Low vitamin B12 levels occur among 1 in 31 adults 51 years of age and older in the U.S. population. Vitamin B12 deficiency is simple to prevent and simple to treat, but the diagnosis is easy to miss and is often overlooked in the outpatient setting.

All patients with unexplained hematologic or neurologic symptoms should be evaluated for a vitamin B12 deficiency. If such a deficiency is found, the cause should be determined.7,44 Irreversible neurologic damage can occur if diagnosis and treatment are delayed.

A complete blood count, peripheral blood smear, and serum vitamin B12 level are the tests of choice for initial assessment of cobalamin deficiency. Keep in mind that megaloblastic anemia and changes in mean corpuscular value (MCV) are not always present when there is a vitamin B12 deficiency . Hcy and MMA can be used to confirm vitamin B12 deficiency in cases with ambiguous initial results because metabolic changes often precede low cobalamin levels.

You have inexpensive treatment options available to treat vitamin B12 deficiency. Remember that treatment is safe, effective, and has no known toxicity level.

To prevent vitamin B12 deficiency, you should advise all patients older than 50 years of age to consume synthetic vitamin B12 daily. Dosage recommendations vary.

Acknowledgements: The authors would like to thank Christine Pfeiffer, PhD, for assistance with laboratory interpretation, and Quanhe Yang, PhD,and Heather Carter Hamner, MS, MPH, for statistical support. We also appreciate the comments and suggestions from our panel of reviewers, including Sonja Rasmussen, MD; Joe Mulinare, MD; R.J. Berry, MD; Lorraine Yeung, MD; Sharon Roy, MD; Mary Dott, MD; John Mersereau, MD; Jennifer Zreloff, MD; Jason Bell, MD; Pauline Terebuh, MD; Dan Watkins, PA; Gail Walls, MSN; Sally Lehr, MSN; Darla Ura, MSN; Sue Ann Bell, MSN; Christa Purnell, MSN; Mary E. Cogswell, DrPH, RN, and Malissa Perritt, MSN.


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