Clearance studies during subsequent sessions of double filtration plasmapheresis.

To evaluate the optimal session of double filtration plasmapheresis (DFP) in terms of the maximal clearance rates for various serum substances, the laboratory parameters of 152 consecutive patients treated with different sessions of DFP following a standard protocol on an alternate-day basis was studied. Immunoglobulin M (IgM) and lipoprotein cholesterol had the most effective clearance by a minimum of two sessions of DFP treatment, and the clearance rates remained relatively constant despite the increase in the number of treatment sessions, while the clearance rates for other serum proteins increased steadily with further treatments. Using the clearance rate of the 2-session group as reference, the highest slopes for clearance of albumin, globulin, and triglyceride were found in the 4-session group, while the slopes for IgA and IgG were highest in the 5-session group. In conclusion, for the clearance of IgM and lipoprotein cholesterol, two sessions of DFP treatment are adequate. However, the best clearance of IgG and other globulins cannot be achieved until the fourth session of DFP treatment. Therefore, a minimum of 4 sessions of DFP treatment at 2-day intervals is needed for most immunological diseases.