Anemia is a common comorbidity of chronic kidney disease (CKD). As the diseased kidney loses its ability to produce the erythropoietin essential to the production of hemoglobin, anemia ensues. The age-related rise in CKD makes anemia in CKD a problem of increasing prevalence among residents of long-term care facilities. CKD refers to the entire continuum of renal disease that progresses from mildly impaired kidney function (stage 1, glomerular filtration rate [GFR] > or =90 mL/min/1.73 m(2)) to significant deterioration, requiring dialysis or kidney transplant in what is categorized as stage 5 (GFR <15 mL/min/1.73 m(2)). The definition of anemia is controversial. The WHO defines anemia as hemoglobin <13 g/dL for men and <12 g/dL for women. The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative, which is the criteria used for Medicare reimbursement, defines anemia in adult men and postmenopausal women as hemoglobin <12 g/dL, or <11 g/dL in a premenopausal woman.