The iron status of blood donors is a subject of concern for blood establishments. The Finnish Red Cross Blood Service addresses iron loss in blood donors by proposing systematic iron supplementation for demographic at-risk donor groups. We measured blood count, ferritin and soluble transferrin receptor (sTfR) and acquired lifestyle and health information from 2200 blood donors of the FinDonor 10000 cohort. We used modern data analysis methods to estimate iron status and factors affecting it with a special focus on the effects of the blood service’s iron supplementation policy. Low ferritin (< 15 μg/L), an indicator of low iron stores, was present in 20.6% of pre-menopausal women, 10.6% of post-menopausal women and 6% of men. Anemia co-occurred with iron deficiency more frequently in pre-menopausal women (21 out of 25 cases) than in men (3/6) or post-menopausal women (1/2). In multivariable regression analyses, lifestyle, dietary, and blood donation factors explained up to 38% of the variance in ferritin levels but only ~10% of the variance in sTfR levels. Days since previous donation were positively associated with ferritin levels in all groups while the number of donations during the past 2 years was negatively associated with ferritin levels in pre-menopausal women and men. FRCBS-provided iron supplementation was negatively associated with ferritin levels in men only. Relative importance analyses showed that donation activity accounted for most of the explained variance in ferritin levels while iron supplementation explained less than 1%. Variation in ferritin levels was not significantly associated with variation in self-reported health. Donation activity was the most important factor affecting blood donor iron levels, far ahead of e.g. red-meat consumption or iron supplementation. Importantly, self-reported health of donors with lower iron stores was not lower than self-reported health of donors with higher iron stores.

Background and Objectives There is increasing evidence that frequent blood donation depletes the iron stores of some blood donors. The FinDonor 10 000 study was set up to study iron status and factors affecting iron stores in Finnish blood donors. In Finland, iron supplementation for at-risk groups has been in place since the 1980s.Material and Methods A total of 2584 blood donors (N = 8003 samples) were recruited into the study alongside standard donation at three donation sites in the capital region of Finland between 5/2015 and 12/2017. All participants were asked to fill out a questionnaire about their health and lifestyle. Blood samples were collected from the sample pouch of whole blood collection set, kept in cool temperature and processed centrally. Whole blood count, CRP, ferritin and sTFR were measured from the samples, and DNA was isolated for GWAS studies.Results Participant demographics, albeit in general similar to the general blood donor population in Finland, indicated some bias towards older and more frequent donors. Participation in the study increased median donation frequency of the donors. Analysis of the effect of time lag from the sampling to the analysis and the time of day when sample was drawn revealed small but significant timedependent changes.Conclusion The FinDonor cohort now provides us with tools to identify potential donor groups at increased risk of iron deficiency and factors explaining this risk. The increase in donation frequency during the study suggests that scientific projects can be used to increase the commitment of blood donors.

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Key Points• We used a registry containing all 1 163 524 blood donor returns that took place in Finland between 2010 and 2015 to evaluate cHb recovery.• Average recovery times for cHb to return to the level of the preceding donation were longer than the minimum allowed donation intervals.Measuring the concentration of capillary hemoglobin (cHb) is a standard procedure before blood donation. To further assess the time period needed for cHb recovery after blood donation and to have a more in-depth understanding of features of recovery, we used datamining tools in a large, retrospective data pool containing all 1 163 524 donor returns that took place in Finland in 2010 to 2015. The results show that the average recovery times for cHb to return back to the level preceding donation were substantially longer, over 200 days in all age groups, than were the minimum allowed donation intervals. cHb recovery was especially poor in women under the age of 30 who returned to donate soon after the minimum allowed donation interval. It was of interest that frequent donors recovered substantially faster, with the average recovery times of ;100 days in men and ;200 days in women, than did infrequent donors, suggesting that there is a subpopulation of donors who can donate frequently without fear of iron deficiency. Return interval in fact explained only 1% of the variation in cHb recovery, which points to unknown, individual features, such as genetic or lifestyle factors, warranting further studies and suggesting that simply extending the allowed donation intervals may not suffice to improve cHb recovery. The study demonstrates that data mining of blood bank records is a powerful tool for depicting features of blood donor population.

BackgroundThere is increasing evidence that frequent blood donation depletes the iron stores of some but not all blood donors. To identify risk groups and factors affecting the iron stores in the Finnish donor population the Fin Donor 10 000 project, a prospective study observing blood donor iron stores and genetic and lifestyle factors associated with iron stores, was set up. Material and methods2584 blood donors (N= 8003 samples) were recruited in the study alongside the standard donation at three fixed donation sites in the capital region of Finland during 5/2015 -12/2017. All participants were asked to fill in a pseudonymized questionnaire about their health and lifestyle; 2562 donors (99.1%) completed it. Blood samples were collected from the sample pouch of whole blood collection set, kept in cool temperature and processed centrally. The samples were sent to a clinical laboratory for analysis of whole blood count, CRP, ferritin and sTFR; in addition, genomic DNA was isolated for GWAS studies. ResultsThe demographics of the participants, albeit in general similar to the general blood donor population in Finland, indicated some bias toward older and more frequent donors, who may be regarded as regular, strongly-committed donors. The effects of the time lag from the sampling to the analysis and the time of the day when sample was drawn was studied and revealed small but significant time-dependent changes in certain measurements. DiscussionIf these time dependent changes are not adequately corrected they may affect the conclusions drawn from similar studies. The FinDonor cohort now provides us with tools to identify the potential risk groups and genetic and non-genetic factors behind their tendency to iron deficiency.