The hyperviscosity syndrome is a common problem in patients suffering from IgM paraproteinemia. In this situation cytotoxic chemotherapy alone is insufficient and additional plasma therapy is required. Until recently, conventional plasma exchange was the only plasma therapy available. While this method has proven its efficacy, it eliminates proteins unselectively. Cascade filtration, on the other hand, has been established to remove
proteins as a function of their size offering the prospect of a highly selective withdrawal of macromolecules. In the work presented, the efficacy of conventional plasma exchange and cascade filtration was evaluated performing both techniques at random in cases of hyperviscosity syndrome due to immunocytoma of Waldenstrom's type (n = 11/group). In these patients, conventional plasma exchange decreased plasma viscosity by 48%; cascade filtration was less effective (26%), correlating with a smaller decrease of IgM (conventional plasma exchange 42% vs cascade filtration 27%). The profile of other plasma proteins studied did not change significantly with either treatment. Furthermore, we observed no differences regarding serious side-effects. In conclusion, we could not demonstrate a superior effect of cascade filtration as compared to conventional plasma exchange in the treatment of hyperviscosity syndrome.