Studies on Normal Values for Red Blood Cells in Korean Children

Kim, Soon Ki; Son, Byong Kwan

Abstract

PURPOSE: Values for hemoglobin, erythrocyte indices and red cell distribution width used in the diagnosis of anemia and iron deficiency are known to vary to some degree according to age. We tried to define age-related changes in red blood cells (RBC) profiles.
METHODS
With the eletronic counters routinely used in clinical laboratories we evaluated the RBC profiles of 1,717 samples of blood from children who were considered healthy. Mean, median and percentile curves of hemoglobin, hematocrit, red cell indices and red cell distribution width were calculated in children aged 5 months to 15 yr of age.
RESULTS
The median values for hemoglobin and hematocrit were increased substantially during childhood. The values of hemoglobin were increased from 11.6 g/dl at 6-11 months, to 12.0 g/dl at 2 yr of age, 12.7 g/dl at 6-8 yr, reaching a maximum level of 13.7 g/dl at 12-15 yr for males and 13.3 g/dl for females, with an average of 13.5 g/dl for both sexes. The values of hematocrit were also increased from 34.4 % at 6-11 months, 35.5 % at 2 yr of age, 37.4 % at 6-8 yr and achieved 39.3 % for males and 38.6 % for females in adolescence. The MCV at 6-11 months was 76.3 fl; at 2 yr 77.1; and 83.4 fl for males and 84.8 fl for females in adolescence. The increase in MCH parallels the MCV fairly closely from 25.9 pg at 6-11 months of age to 29.0 pg at adolescence. The MCHC remains conatant throughout infancy and childhood. Cut-off values (3 percentile) of hemoglobin were 10.7 g/dl at 6-11 months, 11 g/dl at 1-2 yr and 11.5 after 6 yr. Cut-off values (3 percentile) of MCV were 70 fl at 1-2 yr and 75 fl after 6 yr. Correlation between hemoglobin, MCV, MCH and RDW was relatively significant, but it was much less dependent variables in this reference population than in the children with iron deficiency.
CONCLUSIONS
Our findings indicate that there is a developmental change in red blood cell size extending beyond the well-recognized changes seen in the first 6 months of life. Age-related changes in hemoglobin, hematocrit, MCV and MCH must be taken into consideration in order to optimize the identification of individuals with anemia and iron deficiency.