How often should plasma donors be allowed to donate?

30/10/24

Plasma is essential for producing life-saving medicines such as albumin, immunoglobulin (Ig), and clotting factors. The majority of plasma used for manufacturing these plasma-derived medicinal prod-ucts (PDMPs) comes from the United States (US). In the US, plasma donors are permitted to donate up to twice per week, with a maximum of 104 donations per year. In contrast, countries like Belgium allow a much lower donation frequency: once every two weeks, for a maximum of 24 donations per year. While the demand for PDMPs continues to rise, it remains unclear whether very high-frequency plasma donation, as permitted in the US, may have any (long-term) adverse health effects on donors.

To investigate the frequency at which a plasma donor can donate without harm, we conducted a sys-tematic review to investigate the impact of plasma donation frequency on cardiovascular health, pro-tein depletion, and adverse events in healthy plasma donors. We analyzed data from six studies, in-cluding four observational and two experimental studies. The results indicated that donating plasma twice a week, as allowed in the US, might significantly lower levels of ferritin, an important iron stor-age protein, and IgG, a key immune system component. Although the implications of these reductions are not yet fully understood, they suggest that caution is warranted regarding very high-frequency plasma donation. 

Despite these findings, the evidence is not conclusive. The studies we reviewed had small sample sizes and other methodological limitations, making it difficult to draw definitive conclusions. Additionally, the “healthy donor effect”, the observation that donors are generally healthier than the average popu-lation due to the strict eligibility criteria they have to meet, could skew the results.

Therefore, we call for more high-quality research to determine a safe donation frequency. Larger, well-designed studies are essential to provide clear guidelines and ensure donor safety. As the demand for plasma-derived medicines continues to grow, protecting the health of plasma donors remains a top priority.

The full review is published in Transfusion Medicine Reviews and can be read here.