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.

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.