Background: Depending on post-donation erythropoiesis, available iron stores, and iron absorption rates, optimal donation intervals may differ between donors. This project aims to define subpopulations of donors with different ferritin trajectories over repeated donations. Methods: Ferritin levels of 300 new whole blood donors were measured from stored (lookback) samples from each donation over two years in an observational cohort study. Latent classes of ferritin level trajectories were investigated separately using growth mixture models for male and female donors. General linear mixed models assessed associations of ferritin levels with subsequent iron deficiency and/or low hemoglobin. Results: Two groups of donors were identified using group-based trajectory modeling in both genders. Ferritin levels showed rather linear reductions among 42.9% of male donors and 87.7% of female donors. For the remaining groups of donors, steeper declines in ferritin levels were observed. Ferritin levels at baseline and the end of follow-up varied greatly between groups. Conclusion: Repeated ferritin measurements show depleting iron stores in all-new whole blood donors, the level at which mainly depends on baseline ferritin levels. Tailored, less intensive donation strategies might help to prevent low iron in donors, and could be supported with ferritin monitoring and/or iron supplementation.

Many donors are deferred because of low haemoglobin (Hb) levels, especially young (pre-menopausal) women. 1,2 Donating frequently may exhaust iron stores and lead to iron deficiency anaemia. 3 To prevent iron deficiency in blood donors, many blood donation centres have started monitoring ferritin levels in donors. [4][5][6][7][8][9][10] Blood centres use different strategies in managing donors with low ferritin levels. 5,6,11 In some countries donors are given oral iron supplementation, 5,9,12 while in others donors are deferred. 6,10 Nevertheless, donors are still at risk of becoming iron deficient. It would be beneficial for both donor health and blood service efficiency if an optimal donation frequency could be predicted to prevent blood donation-associated iron deficiency.Erythropoiesis and iron status are tightly linked, and inclusion of these processes is a prerequisite for reliable prediction of Hb and ferritin levels in relation to blood donation. Both erythropoiesis and regulation of iron homeostasis are complex processes themselves, and perhaps for this reason, have to date mostly been modelled in isolation. For example, an iron homeostasis model investigating control of liver iron by hepcidin can adequately reproduce findings in haemochromatosis, but considers iron in red blood cells to be

Background: Whole blood donors lose approximately 200-250 mg of iron per donation. Depending on post-donation erythropoiesis, available iron stores, and iron absorption rates, optimal donation intervals may differ between donors. This project aims to define subpopulations of donors with different ferritin trajectories over repeated donations. Methods: Ferritin levels of 300 new whole blood donors were measured from stored (lookback) samples from each donation over a two-year period in an observational cohort study. Latent classes of ferritin level trajectories were investigated using growth mixture models for male and female donors, separately. Associations of ferritin levels with subsequent iron deficiency and/or low haemoglobin were assessed with generalized linear mixed models. Results: In both genders two groups of donors were identified using group-based trajectory modelling. Ferritin levels showed rather linear reductions among 42.9% of male donors and 87.7% of female donors. For the remaining groups of donors, steeper declines in ferritin levels were observed. Ferritin levels at baseline and the end of follow-up varied greatly between groups. Conclusion: Repeated ferritin measurements show depleting iron stores in all new whole blood donors, the level at which mainly depends on baseline ferritin levels. Tailored, less intensive donation strategies might help to prevent low iron in donors, and could be supported with ferritin monitoring and/or iron supplementation.