A comparison of complete blood count reference intervals in healthy elderly vs. younger Korean adults: a large population study

Background: The use of laboratory reference intervals based on younger populations is of questionable validity in older populations. We established reference intervals for 16 complete blood count (CBC) parameters in healthy elderly Koreans aged >= 60 years and compared them to those of individuals aged 20-59 years. Methods: Among 64,532 individuals (39,609 men and 24,923 women) aged >= 20 years who underwent medical checkups, 8151 healthy subjects (12.6%, 5270 men and 2881 women, including 675 and 511, respectively, who were >= 60 years of age) were enrolled based on stringent criteria including laboratory, imaging and endoscopy results; previous medical history; and medication history. CBC parameters were measured using an Advia2120i instrument. Results: Overall, healthy individuals aged >= 60 years did not require separate reference intervals from those aged <60 years except for red cell distribution width (RDW) and mean corpuscular hemoglobin (MCH) in women. However, subjects aged >= 6 years still required sex-specific reference intervals for red blood cell count, hemoglobin, hematocrit, MCH, monocytes and eosinophils. Separate reference intervals were required for MCH, eosinophils and basophils for certain age subgroups of men aged >= 60 years, and for MCH and RDW in certain age subgroups of women aged >= 60 years, compared to counterparts <60 years of age. Conclusions: Healthy elderly Koreans can use the same reference intervals as younger populations. Thus, abnormal CBC results may not necessarily be attributable to physiologic changes but possible underlying diseases that should be investigated.