Mechanisms of unexplained anemia in the nursing home.

OBJECTIVES To characterize anemia in elderly nursing home residents. DESIGN Prospective multiinstitutional cohort study. SETTING Five nursing homes. PARTICIPANTS From retrospective analysis, residents found to be anemic using chart review were prospectively randomized. Of the 81 residents enrolled, 60 were anemic. MEASUREMENTS Chart review for medical history and factors related to treatment or history of anemia, extensive laboratory evaluation for causes of anemia, and classification of anemia by two hematologists. RESULTS Among the 60 anemic residents, the causes of anemia were idiopathic (n=27), iron-deficiency (n=14), anemia associated with chronic disease (n=8), anemia of renal insufficiency (n=6), and other (n=5). The eryrthropoietin (EPO) response to anemia was lower in residents with idiopathic anemia (IA) than in those with iron-deficiency anemia, and this correlated with renal function as estimated using calculated creatinine clearance. In this elderly population, advancing age was not correlated with lower EPO response. CONCLUSION IA is common in nursing home residents. A lower EPO response contributes to the high prevalence of anemia in this setting and may be due, in part, to occult renal dysfunction.