Protein levels and plasmapheresis intensity.

In order to evaluate the influence of intensity of plasmapheresis on donor serum total protein and immunoglobulin concentrations, these parameters were measured monthly in two groups of plasma donors over a period of 6 months. Donors in group one donated 500-600 ml of plasma at weekly intervals and those in the other groups at intervals of 14 days or longer. Regular whole blood donors were used as a control group. The average concentrations of total protein and IgG immunoglobulin fraction in group one were significantly lower (P < 0.002) than those of the other two groups but they always remained well within the normal ranges. Although the mean total protein level of this group of donors fell significantly during the first 3 months, their values returned to almost baseline levels at the end of the study. No statistically significant difference from the initial concentrations was observed during monthly measurements of IgG, IgA and IgM levels among any of the groups studied. We conclude that removal of 500-600 ml of plasma at weekly intervals involves little, if any, risk of total protein or immunoglobulin depletion in donors who satisfy current criteria. This study also suggests that the frequency of IgG and IgM evaluations may be safely lowered and that IgA determinations may be limited to first time plasma donors.