Mr. Johnson, age 57, presented to his physician with marked fatigue, nausea with occasional diarrhea, and a sore, swollen tongue. Lately he also has been experiencing a tingling feeling in

Mr. Johnson, age 57, presented to his physician with marked fatigue, nausea with occasional diarrhea, and a sore, swollen tongue. Lately he also has been experiencing a tingling feeling in his toes and a feeling of clumsiness. Microscopic examination of a blood sample indicated a reduced number of erythrocytes, many of which are megaloblasts, and a reduced number of leukocytes, including many large, hypersegmented cells. Hemoglobin and serum levels of vitamin B 12 were below normal. Additional tests confirm pernicious anemia. Discussion Questions Relate the pathophysiology of pernicious anemia to the manifestations listed above. (See Pernicious Anemia.)