PRISMA-based systematic review on iron stores in repeat blood donors.

Repeat blood donation may progressively reduce iron stores, although the clinical relevance of biochemical iron depletion in otherwise healthy donors remains debated. This PRISMA-based systematic review and meta-analysis evaluated iron depletion among repeat whole-blood donors and explored factors associated with prevalence estimates. Sixteen studies were included in the qualitative synthesis, and 15 contributed to meta-analyses. The pooled prevalence of iron deficiency, associated with serum ferritin measurement, among regular donors was 14.26% (95% CI: 12.50-16.23). Female donors showed a higher pooled prevalence than male donors, and meta-regression identified sex and serum ferritin cut-off values as significant determinants of prevalence, whereas donation frequency was not independently associated. These findings indicate that iron depletion is common among repeat donors but highly dependent on case definitions and donor characteristics. Serum ferritin testing may support risk stratification, but universal screening should be balanced against feasibility, donor-centered outcomes, and local resources, particularly in low and middle income settings.