Which biomarkers are used in staging myeloma with the ISS system?

• A. Serum beta-2 microglobulin and serum albumin
• B. Calcium and phosphate levels
• C. Hemoglobin and creatinine
• D. M protein and free light chain ratio

Answer: (A)

In the ISS staging system for multiple myeloma, two blood biomarkers are used: serum beta-2 microglobulin and serum albumin. Beta-2 microglobulin reflects tumor burden and renal clearance, so higher levels indicate more disease impact; albumin reflects nutritional and inflammatory status, with lower levels signaling worse prognosis. Combining these two markers allows staging: low beta-2 microglobulin and high albumin correspond to Stage I, high beta-2 microglobulin (or low albumin) correspond to Stage III, and values that don’t fit either extreme fall into Stage II. Other measurements like calcium, phosphate, hemoglobin, creatinine, M protein, or free light chain ratio relate to symptoms, organ involvement, or diagnosis, but they are not used for the ISS stage definition. (Note: newer revisions add LDH and cytogenetics, but classic ISS relies on beta-2 microglobulin and albumin.)