NT-proBNP as a Biomarker in MGUS and Multiple Myeloma: A Retrospective Analysis.

: N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a well-established biomarker of cardiac stress and has recently been implicated in hematologic malignancies. However, research on how NT-proBNP changes from monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma (MM), and its association with disease severity and progression, remains limited. This study evaluated whether NT-proBNP levels are associated with disease severity and progression in patients with MGUS and MM. : This retrospective cross-sectional study included 121 patients with MGUS and 472 patients with MM. MGUS risk was stratified based on the presence of three major risk factors, while MM was staged according to the ISS, R-ISS, and R2-ISS systems. Associations between NT-proBNP and clinical or laboratory parameters were evaluated using univariate and multivariate regression. : NT-proBNP levels did not significantly differ between the MGUS and MM groups. In MGUS, NT-proBNP levels were positively associated with β2-microglobulin ( = 0.018) and creatinine ( < 0.001). In MM, NT-proBNP levels increased with advancing disease stage in all staging systems ( < 0.001), but these associations were no longer significant in multivariate models. Instead, β2-microglobulin, LDH, creatinine, and albumin remained independently associated with NT-proBNP levels. : NT-proBNP levels were not associated with MGUS risk factors and showed limited value for risk stratification in MGUS. In MM, NT-proBNP may reflect disease burden but lacks independent value as a marker of disease stage. NT-proBNP may serve as an indicator of overall disease burden, but has limited value as an independent biomarker for disease severity in MM.