Exploring the Relationship between Extended Red Blood Cell Indices and Platelet Indices in Voluntary Blood Donors

Abstract Background As regular blood donors are prone to iron deficiency, the importance of extended red blood cell (eRBC) indices in identifying donors with depleted iron stores was investigated. Thrombocytosis has been well documented in patients affected with iron deficiency anemia. Thus, the significance of eRBC indices in reflecting elevated platelet counts associated with nonanemic iron deficiency was examined in this cohort. Methods Blood samples were collected in EDTA tubes from consenting donors for analyses of routine hematological and eRBC indices. Serum samples were separated for the estimation of iron parameters. Results Iron-deficient donors had significantly altered eRBC indices. Among them, reticulocyte hemoglobin equivalent (Ret-He) with a cut-off of ≥32 pg had an area under the receiver operating characteristic curve (AUC) of 0.822 and showed a sensitivity of 72.5% and a specificity of 77.8% (P < 0.001) in detecting iron deficiency. The combination of Ret-He with combined cell index (CCI) (AUC = 0.825; 66% sensitivity, 91.9% specificity) increased sensitivity and specificity to 90.6% and 98.2%, respectively, in detecting donors affected with iron-restricted erythropoiesis. This cohort had increased platelet counts that showed significant association with Ret-He (b = −0.373, P = 0.007), red blood cell hemoglobin equivalent (b = −0.384, P = 0.005), CCI (b = 0.384, P = 0.006), percentage of red blood cells with mean corpuscular hemoglobin < 17 pg (b = 0.494, P < 0.001), and percentage of red blood cells with mean corpuscular volume < 60 fL (b = 0.299, P < 0.05). Conclusions eRBC indices are useful indicators of nonanemic iron deficiency, which may be enhanced by combining them. A significant relationship between platelet counts and eRBC indices in iron-deficient donors emerges, which has not been explored before.