Interference with Laboratory Test Results Due to Multiple Myeloma Related Hypergammaglobulinemia: An Illustrative Case Report

Introduction: Excessive production of plasma proteins in concentrations exceeding physiologic limits in multiple myeloma can be an important source of laboratory test interference and can potentially affect test methodologies on various instrument platforms.

Case Study: A 56 year old male, presented with generalized weakness and breathlessness on exertion of one month’s duration. Complete blood counts revealed severe anemia with thrombocytopenia and marked increase in rouleaux formation. There was reversal of Albumin: Globulin ratio with increased urea and creatinine, hyponatraemia and hyperphosphataemia. Although there was no bleeding or thrombotic manifestation, coagulogram showed prolongation of both prothrombin time and activated partial thromboplastin time and mixing studies confirmed common coagulation pathway factor deficiency. In view of severe anemia, two units of packed red cells were requested. Antibody screening showed panreactivity in Coombs phase which was equivocal on enzyme phase and all the units put up for crossmatch were compatible in saline phase but 2+ to 4+ incompatible in Coombs phase. Eleven cell antibody identification panel showed panreactivity. Polyspecific direct antiglobulin test was positive and monospecific antihuman globulin direct antiglobulin test confirmed isolated IgG positivity. Antibody screen and identification became negative after warm saline wash and auto-adsorption. X-ray skull and chest revealed multiple punched-out lytic lesions. Bone marrow examination revealed 62% plasma cells. Together with the clinical profile, blood chemistry and radiological parameters, a diagnosis of IgG Lambda multiple myeloma was considered.

Conclusions: Hypergammaglobulinemia secondary to multiple myeloma can potentially produce a plethora of alterations in laboratory tests across different platforms. Clinicians must be cognizant with actionable lab test results and the laboratory must take appropriate timely actions to prevent erroneous results in such patients.