Hemoglobin concentrations in 358 apparently healthy 80-year-old Danish men and women. Should the reference interval...

In elderly Danes, reference intervals for hemoglobin (Hb) concentrations are derived from younger population groups. The aim was to examine reference intervals for Hb and cut-off limits for anemia by application of criteria for normality to a representative population of 80-year-olds.

Participants in this epidemiological health survey cohort were 358 subjects (171 men) 80 years of age. A dietary survey was performed in 232 subjects. Blood samples included Hb, red cell indices, serum ferritin, serum C-reactive protein, renal and hepatic function tests. Normality criteria for Hb were: 1) values in all participants; 2) values in apparently healthy subjects; 3) values in 10-year survivors. Hb was compared with muscle strength, physical performance and diet.

In the entire series, median Hb was 140 g/L, 5-95 percentile 116-160 g/L in men, and 131 g/L, 5-95 percentile 114-147 g/L in women (p<0.001). The prevalence of anemia, as defined by World Health Organization (WHO) criteria, was 18% in men and 17% in women. Apparently healthy iron-replete men (n=129) and women (n=141) had median Hb of 141 g/L and 131 g/L. Median Hb levels were higher in 10-year surviving men (143 g/L) than in deceased men (139 g/L), whereas surviving and deceased women had similar median Hb (131 g/L). Hb and muscle strength were significantly correlated. Subjects with physical performance score >or=20 had a lower frequency of anemia. There was no correlation between Hb and dietary or supplemental iron intake. In men, Hb was correlated to meat consumption.

WHO decision limits for anemia should not be lowered in 80-year-old subjects. "Optimal" Hb concentrations with respect to survival appear to be at least 140 g/L in men and 131 g/L in women. Further research should evaluate whether not only treating anemia, but also increasing Hb by using erythropoietin and hematinics, may improve functional status and survival in the elderly.