Background: Repeat apheresis donation causes a noticeable loss of whole blood: through routine blood tests with every donation as well as through residual blood left within the used apheresis set. While the effect of blood loss on donor iron stores has been widely researched for whole blood donations, fewer and especially contradictory results exist for apheresis donors.
Methods: A retrospective analysis of the donor blood samples (Department of Transfusion Medicine, University Hospital Erlangen) of the past 11 years (n = 52.976) was performed. Serum ferritin and hemoglobin were used to detect iron deficiency. Values at admission were compared to values measured at the donations. To investigate the impact of the donation frequency, this frequency was calculated for every single donor (for the whole duration of 11 years as well as for each individual year). Correlation and regression analyses between frequency and iron parameters were performed. A special group were long-time repeat donors, whose changes in ferritin values were analyzed in comparison to the first-ever ferritin value before the first donation.
Results: All donor groups show significantly lower mean ferritin and hemoglobin values after repeated donations than at admission. Interestingly, there are much more iron-depleted females in the control group than there are iron-depleted males. The correlation and regression analysis showed a significant relationship between donation frequency and iron-deficiency in males, but not in females. The analysis of the long-time repeat donors showed that the relative ferritin value dropped more in males than in females. When comparing iron-depleted long-time donors, females tend to be iron-depleted much more often even before the first donation.
Conclusions: Repeat apheresis donation has a noticeable effect on the iron store of the blood donor, leading to a high percentage of iron-deficient donors, especially in women. The very small correlation between donation frequency and iron depletion for females is most likely due to the fact that women tend to be iron-deficient even before the first donation. Because of the natural variation of inter-donation-intervals, the calculated donation frequency might not be that exact. As a result, the correlation between donation frequency and iron stores might be higher than suggested by this work.