Pseudohypoproteinemia and multiple myeloma
Jay H. Avashia, MD
T. Declan Walsh, MD
Rafael Valenzuela, MD, PhDAddress reprint requests to R.V., Department of Immunopathology, The Cleveland Clinic Foundation, One Clinic Center, 9500 Euclid Avenue, Cleveland, Ohio 44195.
J. Fernando Quevedo, MD
John Clough, MD
Paraproteinemia is an important diagnostic feature of multiple myeloma. The M-protein level reflects tumor burden and helps to determine the response to chemotherapy. A case is described that illustrates the phenomenon of reversible in vitro gelification of an M-protein. Paraprotein IgG1-kappa formed a concentration- and temperature-dependent gel, which was reversed by agitation. Measurement of paraprotein without previous vortexing of the specimen can erroneously lower the apparent M-protein level as well as reduce serum viscosity levels. This phenomenon can downstage the disease at diagnosis, produce inappropriate assessment of treatment response, or lead to premature withdrawal of chemotherapy. In addition, misdiagnosis of hyperviscosity syndrome can occur with serious clinical consequences.