[Contribution to the evaluation of serum levels of selected biological parameters in monoclonal gammopathy of undetermined significance and in individual clinical stages of multiple myeloma].

INTRODUCTION

This study aimed to measure serum levels of 12 selected parameters in patients with monoclonal gammopathy of undetermined significance (MGUS) and initial, asymptomatic phase of multiple myeloma (MM) to assess their potential benefit in differentiating both conditions.

PATIENT SAMPLE AND METHODOLOGY

The analysed sample of 131 patients consisted of 62 patients with MGUS and 69 patients with MM fulfilling the criteria of the International Myeloma Working Group (IMWG). The following techniques were used to assess serum levels: quantitative immunoradiometry (bone-type alkaline phosphatase - bALP and insulin-like growth factor-1 - IGF-1), chemiluminescent enzyme immunochemical reaction (parathormone--PTH), quantitative sandwich enzyme immunoassay (osteopontin--OPN, endostatin (ES), macrophage inflammatory protein-1alpha/beta--MIP-1alpha/beta, angiogenin--ANG a IL-17). Pearson chi2 test and Mann-Whitney U-test were applied during the statistical analysis.

RESULTS

The analysis showed statistically significant differences in serum concentrations between MGUS and symptomatic form of MM (Durie-Salmon (D-S) stage 2-3) for: albumin, beta2-microglobulin (beta2-M) and OPN (p = 0.0001 and < 0.0001); osteocalcin for stage 2 (p = 0.006) and MIP-1alpha for stage 3 patients (p = 0.0002). Using the International Staging System (ISS), statistically significant differences between MGUS and all stages of MM (1-3) were identified for albumin and OPN (p = 0.003 and 0.001 and 0.00009, respectively), stages 2 and 3 for beta2-M and ES (p = 0.015 and 0.0001, respectively), stage 2 for ANG (p = 0.014) and stage 3 for MIP-1alpha (p = 0.00001). Statistically significant differences between MGUS and initial, asymptomatic phase of MM (D-S stage 1) was found only for bALP (p = 0.01) and for albumin (p = 0.004) and OPN (p = 0.003) when ISS was applied. Renal function impairment (D-S substage B) showed in comparison to MGUS significant elevation of serum levels of beta2-M (p < 0.0001), OC (p = 0.011), IGF-1 (p = 0.014), OPN (p = 0.003), ES (p = 0.0001), MIP-1alpha (p = 0.0004) and ANG (p = 0.005) and for albumin (p < 0.0001), beta2-M (p < 0.0001) and OPN (p < 0.0001) only when compared to substage A.

CONCLUSION

Only albumin and OPN showed useful even though non-specific potential to differentiate MGUS from all ISS stages of MM, beta2-M and ES for ISS stages 2 and 3, the other parameters differed for stage 2 (ANG), stage 3 (MIP-1alpha) only and stage 1 (bALP), stage 2 (OC) and stage 3 (MIP-1alpha) when D-S stratification was applied.