In Reply.—Mental dysfunction can be the presenting symptom of cobalamin deficiency in the absence of any hematologic abnormalities. This has been described by many in the past, yet continues to merit emphasis because of its important clinical implications. The letter by Miller and coworkers provides another such welcome reminder.
It is also interesting to note, incidentally, that neither of the patients in the 1983 report by Evans and coworkers1 had pernicious anemia in its currently accepted gastroenterological definition as cobalamin malabsorption due to lack of intrinsic factor. Both patients had normal Schilling test results. In the light of our2,3 and others'4 data, it seems highly likely that their patients' cobalamin deficiency arose from food-cobalamin malabsorption (one of the patients had documented gastric achlorhydria). Thus, physicians must think seriously of cobalamin deficiency in neurologically impaired patients, not only in the face of normal blood cell counts, but
CARMEL R. Mental Dysfunction and Cobalamin Deficiency-Reply. Arch Intern Med. 1990;150(4):911. doi:10.1001/archinte.1990.00390160150034