<prompt> M-spike in multiple myeloma is due to?IgMIgAIgGIgD  <response>: In Multiple myeloma laboratory analyses reveal increased levels of Igs in the blood andor light chains Bence-Jonesproteins in the urine. The most common monoclonal Ig M protein is IgG approximately 55 ofpatients, followed by IgA approximately 25 of cases. 