Prevalence of undiagnosed pernicious anemia in the elderly.

BACKGROUND: Existing information about the prevalence of pernicious anemia is largely based on older surveys that favored florid manifestations, tended to be retrospective analyses of previously diagnosed disease, and usually studied homogeneous European populations. The lack of current data in the United States has, among other things, hampered discussions of the proposal to increase folate intake by the general population.

OBJECTIVE: To estimate the prevalence of undiagnosed and untreated pernicious anemia among the elderly.

METHODS: A prospective survey of cobalamin levels and anti-intrinsic factor antibody was done in the elderly. Blood testing was done in 729 people aged 60 years or older and follow-up assessment with the Schilling test and other tests was offered when results were abnormal.

RESULTS: Seventeen subjects were found to have pernicious anemia, usually with only minimal clinical manifestations of cobalamin deficiency. Although cobalamin deficiency had been suspected by the physicians of three subjects, they had been treated inadequately and still had evidence of deficiency. Excluding these three partially treated subjects from the analysis, 1.9% of the survey population had unrecognized and untreated pernicious anemia. The prevalence was 2.7% in women and 1.4% in men; 4.3% of the black women and 4.0% of the white women had pernicious anemia.

CONCLUSIONS: Undiagnosed pernicious anemia is a common finding in the elderly, especially among black and white women. If these findings can be extrapolated, almost 800000 elderly people in the United States have undiagnosed and untreated pernicious anemia, and, thus, would be at possible risk for masked cobalamin deficiency if exposed to large amounts of folate. This number does not include those elderly with cobalamin deficiency caused by other disorders or the still unknown number of younger people with unrecognized pernicious anemia and other causes of deficiency.