Reticulocyte Hemoglobin Equivalent (RET-He) in Early Detection of Iron Deficiency Among Blood Donors and Its Potential Impact on Donor Eligibility and Transfusion Safety

Blood donation is essential for healthcare, but repeated whole-blood donation can deplete the body's iron stores. Standard pre-donation screening relies on hemoglobin levels to ensure donor safety; however, a drop in hemoglobin is a late sign of iron deficiency. Consequently, donors with subclinical or latent iron depletion often pass standard pre-donation screening unnoticed. The primary purpose of this study is to evaluate the clinical utility of Reticulocyte Hemoglobin Equivalent (RET-He) as an early laboratory marker for detecting iron deficiency among accepted blood donors. Because reticulocytes are newly formed red blood cells, RET-He reflects iron availability for hemoglobin production over the preceding few days, potentially detecting iron limitation much earlier than mature red blood cell indices or standard hemoglobin testing. In this prospective observational study, approximately 300 eligible voluntary blood donors aged 18 to 60 years will be enrolled at the Main Blood Bank of Assiut University Hospitals. At the time of routine donation, blood samples will be analyzed for complete blood count (CBC) with RET-He, serum ferritin, iron profile (serum iron, total iron-binding capacity, and transferrin saturation), and C-reactive protein (CRP) to control for inflammation. Participants will also be reassessed at their subsequent regular donation visit (after 90 days for males and 120 days for females) to evaluate changes in iron indices over time and explore whether adding RET-He improves donor eligibility assessment and long-term donor health.

Inclusion Criteria: * Voluntary blood donors eligible for donation according to standard national and institutional donor-selection criteria. * Adults aged 18 to 60 years. * Meeting accepted pre-donation hemoglobin thresholds for blood donation (hemoglobin ≥ 14.0 g/dL for males and ≥ 12.0 g/dL for females). * Both male and female donors eligible under local blood donation policies. * Provision of written informed consent prior to study participation. Exclusion Criteria: * Known hematological disorders or chronic anemia unrelated to iron deficiency. * Known chronic kidney disease, active malignancy, or chronic inflammatory/autoimmune diseases. * History of recent blood transfusion. * Recent therapeutic iron treatment or regular iron supplementation within the preceding 3 months. * History of recent major bleeding or major surgery. * Inadequate or hemolyzed blood sample, or inability to obtain valid RET-He, complete blood count (CBC), or iron panel measurements. * Donors who withdraw consent.