Pretreatment serum beta 2-microglobulin in multiple myeloma.

Serum beta 2-microglobuline (S-beta 2m) was evaluated in 121 untreated patients with multiple myeloma. Values greater than 3 mg/l were found in 82% of the patients. Mean S-beta 2m values of the total group of patients correlated with clinical stage. However, there was no correlation if values were corrected for S-creatinine. Seventy-nine patients had normal (less than or equal to 106 mumol/l) and 52 patients abnormal S-creatinine. Patients with S-beta 2m values below 7 X 6 mg/l had an estimated median survival of 44 months compared to 12 months for patients with levels above 7 X 6 mg/l. If S-beta 2m values in patients with normal S-creatinine were combined with values corrected for S-creatinine from patients with elevated S-creatinine a beta 2m cut off level of 6 X 6 mg/l gave a median probable survival of 43 months compared to 14 months. We conclude that pretreatment S-beta 2 microglobulin is a useful marker for predicting survival in multiple myeloma. The problem of the relationship between S-beta 2m and S-creatinine is discussed.