Iron deficiency (ID) poses a prevalent concern among blood donors, especially impacting young donors, premenopausal females and frequent donors. In alignment with recommendations to address ID, routine ferritin testing was implemented in a hospital-based donor centre. Data set, encompassing 26 164 ferritin values from 16 464 blood donors over 33 months, were analysed retrospectively. Ferritin levels were assessed concerning donor characteristics such as sex, age, ethnicity and donation frequency. Ferritin testing revealed age, sex and ethnicity variations, emphasising the heightened risk of ID in young females meeting all donation criteria under 23 year of age who demonstrated the lowest mean baseline ferritin (41% [CI: 34%-48%] < 26 ng/mL; 20% [CI: 14%-25%] < 15 ng/mL). Postmenopausal females exhibited ferritin levels similar to similarly aged males. Irrespective of sex, donors showcased mean ferritin recovery within 6 months. Analysis of ferritin recovery post-donation showed a five-fold increase in risk (compared with first visit) of ID when donors return at a 2-month interval. 'Regular' donors (≥10 visits) approach a median steady ferritin level (~30-35 ng/mL) by the sixth visit. As reliance on regular blood donors increases, donation policies must strike a balance between blood centre resources and the risks posed to both regular and at-risk donors. Frequent blood donation led to donors attaining a mean steady state ferritin level above the threshold for ID. At-risk groups, particularly premenopausal females, were several times more likely to experience ID after donation but demonstrated recovery rates similar to their group's baseline levels. This valuable information informed the development of new donor deferral policies.