Monoclonal protein elevation < 3g/dl and no other target organ dysfxn indicative of myeloma (e.g. no CRAB symptoms/findings: hypercalcemia, renal dysfunction, anemia, bone lesions)
Progresses to myeloma ~1%/y
Risk Factors
Age > 50
Symptoms
Sometimes peripheral neuropathy (numbness, neuropathic pain, weakness) without other explanation
Sometimes hypercoaguability that's otherwise unexplained
Physical Exam Findings
No findings of myeloma or other explanation for symptoms
Decreased distal sensation
Inappropriate pain upon even light touch
Impaired reflexes
Sometimes weakness
Tests
SPEP, plasma free light chains, serum immunofixation (type and quantification of monoclonal protein)
Myeloma: 10% plasma cells in BM, > 3g/dl monoclonal protein, and at least 1 CRAB finding/sx; Smoldering myeloma: 10% plasma cells in BM, > 3g/dl monoclonal protein, but no CRAB findings; MGUS: < 10% plasma cells, < 3g/dl monoclonal protein, no CRAB