Latent iron deficiency as a silent driver of donor attrition in high-frequency plateletpheresis donors: a longitudinal cohort study

High-frequency plateletpheresis is crucial for meeting transfusion demands but poses a significant risk of cumulative iron depletion in donors. Current screening protocols relying solely on hemoglobin (Hb) fail to detect latent iron deficiency (LID), a condition where depleted iron stores coexist with normal Hb levels. This study investigated the longitudinal trajectory of iron parameters in high-frequency plateletpheresis donors and quantified the impact of LID on donor deferral and attrition. A retrospective longitudinal cohort study was conducted on 538 eligible plateletpheresis donors at a regional blood center in China from January 2021 to December 2024. Donors were stratified into high-frequency (≥ 10 donations/year) and low-frequency (< 10 donations/year) groups. Longitudinal changes in serum ferritin and Hb were modeled using Generalized Estimating Equations (GEE), adjusting for time-varying inflammation (WBC) and demographics. The association between baseline LID (ferritin < 30 ng/mL) and temporary Hb deferral was assessed using a multivariable modified Poisson regression. Predictors of donor attrition (lapse > 12 months) were identified using a time-dependent Cox proportional hazards model. High-frequency donors exhibited a precipitous decline in serum ferritin over four years (β = -0.42, p < 0.001), with a significant time-by-frequency interaction (β = -0.15, p < 0.001), while Hb levels remained stable. Baseline LID was a potent predictor of future temporary deferral (Adjusted Relative Risk = 3.8, 95% CI: 2.6–5.5). Survival analysis revealed that both the experience of a deferral event (Hazard Ratio [HR] = 2.42, 95% CI: 1.85–3.16) and baseline LID (HR = 1.58, 95% CI: 1.21–2.06) were independent predictors of donor attrition. Subgroup analyses confirmed these risks were consistent across sex, age, and residence status. High-frequency plateletpheresis induces progressive LID that is masked by stable Hb levels. LID serves as a silent precursor to both operational deferral and long-term donor attrition through physiological and psychological pathways. Integrating routine ferritin monitoring and personalized donation intervals into donor management strategies is essential to safeguard donor health and ensure a sustainable platelet supply.