High proportions of iron deficiency and thalassemia in blood donors with low RBC osmotic fragility: a call for targeted public health responses in Southern China

Objective This study aimed to investigate the prevalence and etiological profile of decreased red blood cell osmotic fragility among voluntary blood donors in Shenzhen, China, and to assess the public health implications for donor screening policies and transfusion safety in thalassemia-endemic regions. Methods This cross-sectional study enrolled 362 voluntary blood donors at the Shenzhen Blood Center from July to September 2025. All donors underwent initial hemoglobin screening and red blood cell osmotic fragility testing. Donors with decreased fragility received comprehensive evaluation including complete blood count, serum ferritin measurement, hemoglobin electrophoresis, and thalassemia gene detection. Transfusion efficacy was preliminarily assessed by analyzing recipient hemoglobin increments. Results Among the 14 donors (3.87%) with decreased red blood cell osmotic fragility, 9 (64.3%) were confirmed as thalassemia gene carriers (7 with α -thalassemia, 1 with β -thalassemia, and 1 with compound α/β-thalassemia), and 7 (50.0%) had biochemical iron deficiency (ferritin <30 ng/mL), with 4 individuals meeting both criteria, while 2 donors had neither thalassemia nor iron deficiency. Blood components from donors with decreased osmotic fragility, including those from thalassemia carriers, demonstrated effective hemoglobin recovery in recipients, with post-transfusion increments observed in all transfused cases. Conclusion In Southern China, decreased red blood cell osmotic fragility among blood donors is primarily associated with thalassemia trait and iron deficiency. These findings highlight the need for targeted screening strategies and evidence-based policies to optimize donor health management while ensuring blood safety and availability. The study provides a public health framework for managing subclinical hematological conditions in blood donor populations in endemic regions.