***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: OBJECTIVES To characterize anemia in elderly nursing home residents . DESIGN Prospect i ve multiinstitutional cohort study . SETTING Five nursing homes . PARTICIPANTS From retrospective analysis , residents found to be anemic using chart review were prospect ively r and omized . 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 BACKGROUND To accurately determine the causes of anemia and proportion of unexplained anemia in a racially diverse cohort of older adults after a comprehensive and st and ardized evaluation . METHODS We evaluated results from a single-institutional university anemia clinic . Patients with anemia , defined as a hemoglobin less than 13.0 g/dL for men and less than 12.0 g/dL for women , underwent a prospect i ve st and ardized history , physical examination , and laboratory measures , with additional studies including bone marrow examination as indicated . Empiric treatment trials were given for identified deficiencies . RESULTS One hundred and seventy-four primarily community-dwelling adults aged 65 years and older were evaluable . African Americans accounted for 69 % of patients and whites were 27 % . Anemia etiologies included iron deficiency anemia at 25.3 % , anemia of chronic inflammation at 9.8 % , and hematologic malignancy in 7.5 % . Unexplained anemia in the elderly accounted for 43.7 % and predominated in both African Americans and whites . The prevalence of iron deficiency anemia and hematologic malignancies did not differ by race . Unexplained anemia in the elderly showed a consistent phenotype composed of a hypoproliferative mild-to-moderate anemia with suppressed serum erythropoietin . Specifically , erythropoietin levels showed no correlation with hemoglobin concentration in unexplained anemia in the elderly ( r = -.15 , p = .19 ) as opposed to iron deficiency anemia ( r = -.63 , p < .0001 ) . CONCLUSIONS In summary , an intensive hematologic evaluation reveals a wide number of anemia etiologies among older adults , including 7.5 % with hematologic malignancies ; nevertheless , unexplained anemia in the elderly prevails as the most common category in whites and African Americans BACKGROUND In the older population , anemia has been associated with poor outcomes including disability and mortality . Underst and ing the mechanisms leading to anemia is essential to plan better treatment and prevention strategies . We tested the hypothesis that the age-related decline in kidney function is associated with an increased prevalence of anemia and that such an increase is accompanied by a concomitant decrement in erythropoietin levels . METHODS Data were from the InCHIANTI study , a population -based study performed in a sample of community-dwelling older ( > or = 65 years ) persons living in Italy . This analysis included 1005 participants with complete data on hemoglobin and erythropoietin levels and markers of renal function . RESULTS The prevalence of anemia according to the World Health Organization criteria ( hemoglobin level < 12 g/dL for women and < 13 g/dL for men ) was 12.0 % and increased with age in both sexes . After adjusting for age , diseases , and other confounders , only participants with a creatinine clearance ( CrCl ) of 30 mL/min or lower ( < or = 0.50 mL/s ) had a higher prevalence of anemia compared with those with a CrCl higher than 90 mL/min ( > 1.50 mL/s ) ( P<.01 ) . Consistently , participants with a CrCl of 30 mL/min or lower ( < or = 0.50 mL/s ) had significantly lower age- and hemoglobin-adjusted erythropoietin endogenous levels . After excluding men and women with CrCl of 30 mL/min or lower ( < or = 0.50 mL/s ) and adjusting for confounders , we found a trend toward an increase in prevalence of anemia with decreasing renal function ; however , it was not statistically significant . CONCLUSIONS Severe age-related decline in renal function is associated with a reduced erythropoietin secretion and anemia . Whether moderate kidney impairment in older persons is associated with a progressively increasing risk of anemia remains to be determined The reasons for inadequate production of  erythropoietin ( EPO ) in patients with ESRD are poorly understood . A better underst and ing of EPO regulation , namely oxygen-dependent hydroxylation of the hypoxia-inducible transcription factor ( HIF ) , may enable targeted pharmacological intervention . Here , we tested the ability of fibrotic kidneys and extrarenal tissues to produce EPO . In this phase 1 study , we used an orally active prolyl-hydroxylase inhibitor , FG-2216 , to stabilize HIF independent of oxygen availability in 12 hemodialysis ( HD ) patients , six of whom were anephric , and in six healthy volunteers .  FG-2216 increased plasma EPO levels 30.8-fold in HD patients with kidneys , 14.5-fold in anephric HD patients , and 12.7-fold in healthy volunteers . These data demonstrate that pharmacologic manipulation of the HIF system can stimulate endogenous EPO production . Furthermore , the data indicate that deranged oxygen sensing -- not a loss of EPO production capacity -- causes renal anemia OBJECTIVES To examine whether anemia is associated with a higher incidence of recurrent falls . DESIGN Prospect i ve cohort study . SETTING Community-dwelling sample in The Netherl and s. PARTICIPANTS Three hundred ninety-four participants aged 65 to 88 from the Longitudinal Aging Study Amsterdam . MEASUREMENTS Anemia was defined according to World Health Organization criteria as a hemoglobin concentration less than 12 g/dL in women and less than 13 g/dL in men . Falls were prospect ively determined using fall calendars that participants filled out weekly for 3 years . Recurrent fallers were identified as those who fell at least two times within 6 months during the 3-year follow-up . RESULTS Of the 394 persons , 11.9 % ( 18 women and 29 men ) had anemia .  The incidence of recurrent falls was 38.3 % of anemic persons versus 19.6 % of nonanemic persons ( P=.004 ) . After adjustment for sex , age , body mass index , and diseases , anemia was significantly associated with a 1.91 times greater risk for recurrent falls ( 95 % confidence interval=1.09 - 3.36 ) . Poor physical function ( indicated by muscle strength , physical performance , and limitations ) partly mediated the association between anemia and incidence of recurrent falls . CONCLUSION Late-life anemia is common and associated with twice the risk of recurrent falls . Muscle weakness and poor physical performance appear to partly mediate this association PURPOSE Anemia is prevalent in old age and is potentially modifiable , but its effects on physical function have not been determined . We examined whether anemia in older persons increases the risk of subsequent decline in physical function , as measured by objective performance-based tests . METHODS Participants in this 4-year prospect i ve cohort study included 1146 participants , aged 71 years or older , living in Iowa and Washington counties , Iowa . Anemia was defined according to World Health Organization ( WHO ) criteria as a hemoglobin concentration below 12 g/dL in women and below 13 g/dL in men . An  assessment of st and ing balance , a timed 2.4-m walk , and a timed test of five chair rises  were used to assess physical performance ; these were combined into a 0 ( poor ) to 12 ( excellent ) summary scale . RESULTS After adjustment for baseline performance score , health status , and demographic characteristics , anemia was associated with greater mean decline in physical performance over 4 years ; the adjusted mean decline was 2.3 ( 95 % confidence interval [ CI ] : 1.7 to 2.8 ) in subjects with anemia and 1.4 ( 95 % CI : 1.2 to 1.5 ) in those without anemia ( P = 0.003 ) . The association between anemia and greater physical decline was also present in participants who were free of diseases associated with anemia ( cancer , infectious disease , and renal failure ) , and after adjustment for serum cholesterol , iron , and albumin levels . Persons with borderline anemia , a hemoglobin concentration within 1 g/dL above the WHO criteria , also showed greater mean physical decline ( 1.8 ; 95 % CI : 1.5 to 2.2 ) than did those with higher hemoglobin concentrations ( P = 0.02 ) . CONCLUSION This study suggests that anemia in old age is an independent risk factor for decline in physical performance The aim of this study was to prospect ively determine the etiology of anemia in a cohort of community-dwelling older out patients 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 out patients . Iron deficiency anemia is also common and can be difficult to diagnose , and frequently the anemia is not fully corrected with iron repletion PURPOSE To explore the impact of varying hemoglobin levels on mortality , function , and cognition in a representative population of older persons . METHODS Participants in this prospect i ve cohort study included 1 744 men and women , aged 71 years or older , from a r and om household sample living in Durham and surrounding counties in North Carolina .  Hemoglobin levels were obtained from participants at baseline in 1992 . Functional status was measured at the 4-year follow-up interview using Katz and instrumental activities of daily living . Cognition was measured using the Short Portable Mental Status Question naire ( SPMSQ ) . Death was determined by search of the National Death Index , and all deaths through 2000 are included . RESULTS Using World Health Organization ( WHO ) criteria , the prevalence of anemia was 24 % . There was a strong racial difference with an odds ratio , adjusted for age , education , estimated glomerular filtration rate and comorbidity of 3.0 ( 95 % CI , 2.3 - 3.9 ) in African Americans compared with Caucasians . The risk ratio for 8-year mortality was 1.7 ( 95 % CI , 1.5 - 2.0 ) for anemic subjects ( P = .0001 ) and did not differ by sex or race . Anemia was strongly associated with poorer physical function ( P = .0001 ) and cognitive function ( P = .0001 ) , and predicted decreases in both over a 4-year period . CONCLUSIONS In an elderly community-based population , anemia is more prevalent in African Americans and is independently associated with increased mortality over 8 years for both races and sexes . Anemia also is a risk factor for functional and cognitive decrease 
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Conclusion : Our findings suggest that erythropoietin levels in AUE , although elevated , remain inappropriately low , particularly when compared with other forms of anemia .
This suggests a relative erythropoietin deficiency or a blunted erythroid cell response