When you donate plasma, a liquid called citrate is added to your blood to prevent it from clotting during the process of separating the platelets and red cells from the rest of your blood. However, some of this citrate will enter your body and can cause a temporary reduction in calcium.
The citrate anticoagulant used during apheresis reduces ionized calcium levels by binding it to other components (especially magnesium) in the plasma. This causes a drop in blood pressure and an increase in heart rate. It also affects enzymes, including phosphofructokinase and isocitrate dehydrogenase, which impact the conversion of glucose to energy.
A mild reaction to citrate usually involves a feeling of coldness or tingling in the lips, tongue and extremities. More serious symptoms include muscle twitching, breathing difficulties or disturbance of the heart rhythm.
This reaction is more common in platelet and leukapheresis donors than in PBPC or plasma donations, but it can occur in any type of donor. The good news is that it only lasts a short time, and the symptoms disappear immediately after the procedure is finished.
In one study, the use of a sports drink to supplement with calcium carbonate prior to PBPC apheresis completely prevented citrate-related toxicity in all participants, even first-time donors. However, a recent report of bone density measurements in serial plateletpheresis and leukapheresis donors suggests that long-term citrate exposure has a negative impact on bone density. More research is needed to determine if this effect will be persistent.