Canterbury DHB
Clinically, the main reason to separate MGUS from Smouldering Myeloma (SMM) is that the risk of progression to symptomatic myeloma is different (1% per year for MGUS versus 10% per year for SMM).
Other factors may assist in predicting when the transformation to myeloma will occur. An abnormal Serum Free Light Chain ratio and a non-IgG M protein carry a higher risk of transformation (see Rajkumar et al Lab Findings and Prognosis, MGUS and SMM).
Topic Code: 39809