A new form of myeloma "kidney": shortened hemofilter survival and implications for membrane filtration plasmapheresis

Background: Despite rigorous focus on extracorporeal CRRT parameters such as access, blood flow, hemoconcentration, and anticoagulation, some patients have unexpected repetitive hemofilter clotting. We instead explored patient or disease-related factors that could be responsible, and present a case of plasma cell dyscrasia in which para-proteins caused hollow fiber failure. Methods: A patient with IgG kappa chain multiple myeloma complicated by sepsis and acute renal failure was started on CVVH with a regional citrate anticoagulation protocol that typically yields filter life of > 50 h. Polysulfone hemofilters repetitively clotted every 2 - 4 h, even after excluding circuit-related problems. Failed filters were examined by light, electron (EM), and immunofluorescence (IF) microscopy. Results: Imaging of the hemofilters revealed several ultrastructural features typical for myeloma-associated alterations in native human tissue. Red cell rouleaux formation occurred within the hollow fibers. There was extensive protein layering on the luminal surface of the fibers with some extension into their walls: these deposits were IF+ for IgG kappa, and had a fibrillary substructure on EM. Conclusion: Extracorporeal hollow fiber phenomena recapitulate many intra-corporeal paraprotein effects such as those described in the kidney with plasma cell dyscrasias. Rapid protein layering suggests fouling of the membrane, decreased solute clearance before total device failure, and raises the theoretical concern that this might also occur during filtration plasmapheresis: we thus suggest serial serum free light chain levels to confirm their removal when using that technique. These findings emphasize the importance of disease rather than circuit-related factors that are under-appreciated causes of premature hemofilter failure.