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Appendix A: Answers to Case Study Questions

1) Do any of the presenting complaints raise your index of suspicion about a possible vitamin B12 deficiency? If so, why? Yes. Complaints of tiredness for 2 months and memory problems in a woman might indicate vitamin B12 deficiency.

2) What risk factors does this woman appear to have for a vitamin B12 deficiency? The only immediately apparent risk factor is her age. Risk of developing a deficiency begins to increase at 51 years of age. Sex is not an important predictor. The patient’s nutritional status is unclear at this stage. Future questions might usefully probe the patient for regular sources of vitamin B12, including meat and dairy products as well as fortified foods and nutritional supplements.

3) Does the fact that she appears to be “well-nourished” indicate she is unlikely to have a vitamin deficiency? Why or why not? No. The fact that she appears well-nourished does not rule out a potential deficiency. Weight, or body mass index, is not a useful predictor. Normal and overweight individuals might still have a significant vitamin B12 deficiency because most deficiencies are due to malabsorption rather than malnutrition. Markedly underweight patients, who might truly be malnourished, are at increased risk for a vitamin B12 deficiency, particularly if they are elderly or have been adhering to a vegan diet for several years.

4) Are there any aspects of her physical exam that suggest a B12 deficiency? Mucosal and skin pallor are subtle signs.

5) Given her history and physical exam findings, what laboratory test(s) would you order? In addition to the usual chemistry panel and complete blood count (CBC) with smear to check for anemia, a serum B12 test should be ordered. Low-normal levels indicate a need for further assessment because serum levels can be maintained at the expense of liver stores even in the presence of ongoing malabsorption.

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