If collection of plasma by pheresis occurs more frequently than once every 8 weeks, which analyte must be monitored at 4-month intervals?

• A. Iron
• B. Total protein
• C. Calcium
• D. Albumin

Answer: (B)

Frequent plasma pheresis removes a large portion of the proteins circulating in plasma, and the body takes time to replace those proteins. Because of that, checking how much protein is present in the plasma over time is the most informative way to ensure donor safety when donations are more frequent than every 8 weeks.

Total protein in plasma reflects the sum of albumin and all globulins, giving a complete picture of the donor’s protein reserves. If total protein remains adequate, it indicates that the donor’s protein stores are being replenished adequately between donations. Monitoring albumin alone could miss declines in other plasma proteins, while iron levels aren’t directly impacted by plasma donation (red cells aren’t removed), and calcium is acutely affected by the citrate used during apheresis rather than reflecting long-term protein status. Thus, total protein is the most appropriate analyte to monitor at 4-month intervals.