UNLABELLED: Toxic phytanic acid concentrations in patients with Refsum's disease can be reduced by plasma separation, performed either as plasmapheresis, or as cascade filtration. The latter procedure is as efficient and safe as plasmapheresis, and eliminates the need for albumin replacement. This study investigates the loss of immunoglobulins associated with the procedure. MATERIAL AND METHODS: Immunoglobulin- and phytanic acid serum concentrations before and after cascade filtration (n = 16) were measured in a patient with Refsum's disease and their removal determined. Filters with sieving coefficients for immunoglobulin G of 70% and 30% were compared with each other and with historical data on plasmapheresis. RESULTS: While differences in immunoglobulin M loss are negligible, the loss of immunoglobulin G in cascade filtration is significantly less than that reported for plasmapheresis and depends upon the pore size of the employed filters. The loss is least with larger pore size, but this advantage becomes statistically insignificant if immunoglobulin G loss is related to the lesser decrease in phytanic acid concentration that was achieved simultaneously in this study. CONCLUSION: Unless transplantation of a-hydroxylase containing tissue can be established as treatment for Refsum's disease, cascade filtration appears to be the treatment of choice in order to avoid loss of albumin and to reduce the loss of immunoglobulin G.
UNLABELLED: Toxic phytanic acid concentrations in patients with Refsum's disease can be reduced by plasma separation, performed either as plasmapheresis, or as cascade filtration. The latter procedure is as efficient and safe as plasmapheresis, and eliminates the need for albumin replacement. This study investigates the loss of immunoglobulins associated with the procedure. MATERIAL AND METHODS: Immunoglobulin- and phytanic acid serum concentrations before and after cascade filtration (n = 16) were measured in a patient with Refsum's disease and their removal determined. Filters with sieving coefficients for immunoglobulin G of 70% and 30% were compared with each other and with historical data on plasmapheresis. RESULTS: While differences in immunoglobulin M loss are negligible, the loss of immunoglobulin G in cascade filtration is significantly less than that reported for plasmapheresis and depends upon the pore size of the employed filters. The loss is least with larger pore size, but this advantage becomes statistically insignificant if immunoglobulin G loss is related to the lesser decrease in phytanic acid concentration that was achieved simultaneously in this study. CONCLUSION: Unless transplantation of a-hydroxylase containing tissue can be established as treatment for Refsum's disease, cascade filtration appears to be the treatment of choice in order to avoid loss of albumin and to reduce the loss of immunoglobulin G.