Plasma cell dyscrasias are common causes of peripheral neuropathy. Peri pheral neuropathy may be the first manifestation of multiple myeloma, amyloidosis, or monoclonal gammopathy of undetermined significance (MGUS). Peripheral neuropathy occurs in more than one-half of patients with osteosclerotic myeloma. The hematologic disorders are such an important association with peripheral polyneuropathy that, for the last decade, we have obtained a metastatic bone survey and immunoelectrophoresis of serum and a 24-hour urine specimen on all patients older than 40 years with undiagnosed peripheral...