Causes of anemia in the population over age 65 years are relatively few. According to an analysis of the Third National Health And Nutrition Examination Survey (NHANES III), 34% of anemia in older adults was due to folate, B12, or iron deficiency alone or in combination. Twenty percent had anemia of chronic disease (ACD), 12% were associated with renal insufficiency, and in this study, the remaining 34% were unexplained.5 While relative percentages vary between studies with the population being examined, the causes of anemia in all older patients are remarkably constant (Table).
Iron deficiency is frequently seen in the elderly and usually is a result of acute or chronic blood loss through the gastrointestinal tract. ACD is associated with several conditions more common in older persons: inflammatory diseases, malignancy, diabetes, heart failure, and stroke.
Normal B12 absorption requires gastric acid, intrinsic factor (IF), and a terminal ileum. Autoimmune destruction of IF-secreting parietal cells, or pernicious anemia, accounts for approximately 2% of the population over age 60 years. Atrophic gastritis and hypochlorhydria may progress with advancing age and may be partly responsible for the 12% of patients over age 75 years who will have a low B12. The majority of older patients with vitamin B12 deficiency are found to malabsorb dietary protein-bound vitamin B12.29 Short-term studies suggest that proton pump inhibitors and H2 blockers also produce malabsorption of protein-bound B12 by suppressing acid production further.30,31 Post-gastrectomy states, pancreatic insufficiency, and disease or resection of the terminal ileum also impair absorption of B12.
In most studies, 15-30% of patients studied will not have an explanation for their anemia. This may be a function of the intensity of the investigation.
Source: www.clinicalgeriatrics.com
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