Does plasmapheresis remove free LCs in myeloma?
Patients with AKI from myeloma cast nephropathy have very high circulating and tissue FLC because of uncontrolled production and impaired excretion. The reduction of this burden by enhanced non-kidney clearance while awaiting clinical benefit from chemotherapy may allow kidney recovery. Conventional dialysis has very low FLC clearance, and plasmapheresis was used to improve plasma clearance. The modeling of clearance suggests that plasmapheresis can reduce the FLC load, but because there is a high extravascular refilling and exchanges are limited to around 3.5 L volumes, it requires daily treatment. Comparison with daily dialysis using HCO membranes (see Question 14) suggests plasmapheresis is inferior, and clinical trials have not shown a benefit of plasmapheresis in MCN. Plasma exchange should be used only in patients with symptoms and signs of hyperviscosity (e.g., in IgA myeloma and Waldenström macroglobulinemia [WM]) when rapid lowering of whole Igs is required to alleviate symptoms.