Thanks for your question on HCM. M spike on electrophoresis is the diagnostic criteria for multiple myeloma. This is due to high levels of immunoglobulin (protien s) , which gives positive spike on electrophoresis. But when the level of immunoglobulin s are high but not very high as seen in multiple myeloma, it gives non specific (non cancerous) M spike. It is seen commonly in infection and inflammation. So this is not cancer. So no need to worry much for non cancerous spike. Very less chances of it to turn into malignancy. Regular follow up with electrophoresis and bone scan is needed to diagnose multiple myeloma in such cases.