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.