The Development Of Athlete-Specific Hematological Reference Intervals And The Effect Of Ethnicity On Key Hematological Markers
Authors: Lobigs Louisa 
Published: November 2013

Background and Objectives: The development of athlete-specific hematological reference ranges are essential for sports physicians in the diagnosis of pathologies. Due to unique genetics and training modalities, athletes are known to have atypical hematologic profiles in comparison to the general population and between ethnic groups. The aims of this study were 1) to develop athlete-specific reference ranges and 2) to demonstrate the effect of ethnicity on key hematological variables, in order to improve athlete care. Methods: From a reference population of 2082 healthy male (M) (23.28 ± 4.89 years of age) and 140 healthy female (F) (21.16 ± 4.61 years of age) athletes screened at Aspetar hospital, the reference intervals (2.5 and 97.5 percentiles) were established for the following hematological parameters: mean cell volume (MCV, fL), mean corpuscular hemoglobin (MCH, pg), mean corpuscular hemoglobin concentration (MCHC, g/dL), hemoglobin concentration ([Hb], g/dL), hematocrit (HCT, L/L), red blood cell count (RBC, x1012/L), red blood cell distribution width (RDW, %), reticulocyte percentage (RET, %), ferritin (FRT, µg/L), iron (FE, µmol/L), transferrin (TF, g/L), total iron binding capacity (TIBC, µmol/L) and soluble transferrin receptor (STFR, g/L). Additionally, differences in the mean value of each hematological variable between five major ethnic groups were investigated. Results: The calculated overall reference intervals for the majority of the hematological parameters appear to trend lower in comparison to those currently in use, only STFR and RDW yielded slightly higher reference values (Table 1). The athlete population comprised of 104 different nationalities, which were subsequently characterized into five major ethnic groups: Arabic (1145 M, 89 F), Asian (43 M, 4 F), Black (519 M, 43 F), Caucasian (302 M, 4 F) and Mixed (73 M, 0 F). Significant between group differences was found for the male Arabic population (p<0.005). Arabic athletes were found to have lower mean MCV (83.0 ± 6.9), MCH (28.3 ± 2.4), [Hb] (14.6 ± 1.1), HCT (0.43 ± 0.03) and FRT (78.3 ± 57.1) counts and higher RBC (5.2 ± 0.5), RDW (14.9 ± 1.0), TIBC (57.8 ± 9.1) and STFR (2.1 ± 1.6) counts (mean ± standard deviation) in comparison to Black, Caucasian or Mixed males, suggesting a higher prevalence of hematologic disorders, iron deficiency, anemia and/or hemoglobinopathy in this population. In addition, male Black athletes presented with lower mean values for MCV (84.7 ± 5.0), MCH (28.6 ± 2.0) and [Hb] (14.5 ± 1.0) and higher RET (0.99 ± 0.42) and STFR (2.3 ± 3.3) values when compared to male Caucasians. Conclusions: The developments of population-specific athlete hematological indices are important for the sports medicine community, in order to not only improve athlete health and performance, but also to assist in the diagnosis of hemopathologies and other blood related disorders. Additionally, an athlete's ethnicity has a significant impact upon their hematological profile and consequently, published reference ranges are not applicable to certain ethnicities.