M-component

A monoclonal immunoglobulin produced by a single clone of plasma cells, detectable as a discrete monoclonal band (M-protein spike) on serum or urine protein electrophoresis, reflecting clonal plasma cell or B-cell proliferation.

Causes

• Plasma cell disorders

  • Monoclonal gammopathy of undetermined significance (MGUS)

  • Multiple myeloma

  • Smoldering multiple myeloma

  • Plasma cell leukemia

  • Solitary plasmacytoma

• B-cell lymphoproliferative disorders

  • Waldenström macroglobulinemia

  • B-cell non-Hodgkin lymphomas with plasmacytic differentiation

  • Chronic lymphocytic leukemia with monoclonal protein production

• AL (light-chain) amyloidosis

• Autoimmune disorders with monoclonal gammopathy

• Infections with transient monoclonal gammopathy

• Age-related clonal plasma cell expansion