Patient presents with signs and symptoms suggestive of monoclonal gammopathy of undetermined significance (MGUS) or monoclonal paraproteinemia, possibly progressing towards multiple myeloma.  Presenting complaints include fatigue, bone pain specifically in the back or ribs, recurrent infections, and unexplained weight loss.  Laboratory findings reveal an M-spike on serum protein electrophoresis (SPEP) and immunofixation (IFE) confirming the presence of a monoclonal protein.  Quantitative immunoglobulin levels (IgG, IgA, IgM) have been measured.  A bone marrow biopsy has been ordered to assess plasma cell percentage and rule out smoldering multiple myeloma or active multiple myeloma.  Skeletal survey or low-dose CT scan is planned to evaluate for lytic lesions.  Urinalysis including Bence Jones protein is pending.  Differential diagnosis includes other plasma cell dyscrasias, Waldenstrom's macroglobulinemia, and amyloidosis.  Current plan is to monitor patient closely with serial SPEP, IFE, and free light chain assays.  Patient education provided regarding the nature of monoclonal gammopathy, potential complications, and the need for ongoing surveillance.  Referral to hematologyoncology is made for further evaluation and management.  ICD-10 code M80.00 (Monoclonal gammopathy of undetermined significance) is tentatively assigned, pending further diagnostic workup.  Medical billing codes will be finalized upon completion of the diagnostic evaluation and establishment of a definitive diagnosis.