The aim of this study was to prospectively determine the etiology of anemia in a cohort of communitydwelling
older outpatients with a comprehensive hematologic evaluation. Participants were men and women
age 65 and older with anemia as defined by World Health Organization criteria recruited from outpatient
hematology clinics at Stanford Hospital and Clinics (SHC) and Veterans Affairs Palo Alto Health Care System
(VAPAHCS). Each participant underwent a history and physical examination, followed by a comprehensive
hematologic evaluation, which in all participants included complete blood count, red cell indices, review of
the blood smear, and assessment of vitamin B12, folate, iron status and renal function. Additional evaluation
was obtained by clinical providers as per their discretion. 190 participants enrolled and completed the
evaluation. Twelve percent of participants had iron deficiency anemia. Of those with iron deficiency in whom
there was follow-up information, half normalized their hemoglobin in response to iron repletion, and half did
not. Thirty-five percent of participants had unexplained anemia. Those with unexplained anemia had mildly
increased inflammatory markers compared to non-anemic controls, and, at the lower hemoglobin ranges had
relatively low erythropoietin levels. Sixteen percent of participants were categorized as being “suspicious for
myelodysplastic syndrome.” Thus, even with comprehensive hematologic evaluation, unexplained anemia is
common in older anemic outpatients. Iron deficiency anemia is also common and can be difficult to diagnose,
and frequently the anemia is not fully corrected with iron repletion.