According to the staging criterion of International Staging System (ISS) , MM patients were classified into stageⅠ (18 cases), stage Ⅱ (23 cases) and stage Ⅲ (48 cases). The results of serum IFE and bone marrow cell morphology examination in all patients were compared, and the correlation between all indicators and ISS staging was analyzed.

Immunoglobulin (Ig) G was the main type among the clinical stages. The positive rates of M protein and myeloma cell percentage in stage Ⅱ and Ⅲ were higher than those in stageⅠ(P<0.05). The positive rates of M protein in stage Ⅲ and overall positive rate were significantly higher than those of bone marrow cell morphology (myeloma cell percentage ≥10% as standard) (P<0.05). The difference of M protein and bone marrow cell morphology positive rates between the clinical stages was statistically significant (P<0.05).

The positive rate of M protein and myeloma cells percentage have an increasing trend with the increase of clinical ISS stage in MM patients.