A 38-year-old vegetarian (vegan) Caucasian female presents to her primary
care doctor with fatigue and tingling/numbness in her extremities (bilateral).
The symptoms have been gradually getting worse over the last year. Upon fur-
ther questioning she reports frequent episodes of diarrhea and weight loss. On
exam, she is pale and tachycardic. Her tongue is beefy red and a neurologic
exam reveals numbness in all extremities with decreased vibration senses.
A CBC demonstrates megaloblastic anemia.
What is the most likely diagnosis?
What is the most likely underlying problem for this patient?
What are the two most common causes of megaloblastic anemia
and how would this patient’s history and examination differentiate