Hemoglobin concentration reference interval revisited: A nationwide study from Korea

Background: Anemia is a common cause among the elderly for increased mortality. Hemoglobin concentration can be affected by many factors, but the reference interval defined by the World Health Organization has not been adjusted for the previous half century. Methods: Through using the dataset generated by the National Health Insurance (NHI) health screening program of Republic of Korea, here we attempt to present a close to actual hemoglobin concentration of the Korean population. Between January 2009 and December 2013, a total of 57,409,872 health screening events were registered in the NHI database. Following the exclusion criteria, 6,759,566 participants were enrolled for analyses. Results: Significant portion of the study population was considered ‘anemic’, while the mean value (2.5% ~ 97.5%) of hemoglobin concentration from the study was 14.8 (12.5 ~ 16.8) g/dL in men and 12.8 (10.6 ~ 14.7) g/ dL in women. Concordant results of hemoglobin concentration declining with age were observed as previous studies have described, supporting the need for separate, possibly lower cutoff in the elderly. Conclusions: A considerable portion of the participants being categorized as anemia contests the accuracy of the current lower cutoff for anemia. From a large representative dataset, the need for adjustment to the lower cutoff for anemia is suggested.