Serum Beta-2 Microglobulin is a protein that is found on the surface of many cells and plentiful on the surface of white blood cells. Increased production or destruction of these cells causes Serum β2 (beta-2) Microglobulin level to increase. Elevated Serum β2 (beta-2) Microglobulin level is a prognostic factor for plasma cell myeloma.

Serum Beta-2 Microglobulin Pretreatment Level is a prognostic factor required in AJCC 8th edition, Chapter 82 Plasma Cell Myeloma and Plasma Cell Disorders, for staging of plasma cell myeloma. It is a new data item for cases diagnosed 1/1/2018+.

0	ß2-microglobulin <3.5 mg/L
1	ß2-microglobulin =3.5 mg/L <5.5 mg/L
2	ß2-microglobulin =5.5 mg/L
7	Test ordered, results not in chart
9	Not documented in medical record Serum Beta-2 Microglobulin Pretreatment Level not assessed or unknown if assessed

Each Site-Specific Data Item (SSDI) applies only to selected primary sites, histologies, and years of diagnosis. Depending on applicability and standard-setter requirements, SSDIs may be left blank.