Clinical and laboratory characteristics of patients with monoclonal gammopathy of undetermined clinical significance

Introduction: Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant condition with a potential risk of progression to malignant hematological neoplasms. Aim: The aim of this study was to analyze the clinical and laboratory characteristics of patients with MGUS and to determine prognostic factors contributing to the progression of this premalignant condition. Material and methods: The study included 190 patients with MGUS who were diagnosed and monitored at the Clinic for Hematology, University Clinical Center of Serbia, from 2000 to 2024. Data were analyzed to record the demographic and clinical-laboratory characteristics of MGUS patients. Results: The majority of patients belonged to the low-risk group (according to the Mayo Clinic risk stratification), comprising 104 patients (55%), while the intermediate-low risk group included 67 patients (35.5%). Seventeen patients were in the intermediate-high-risk group (9%), and one patient (0.5%) was in the high-risk group. Progression occurred in 6.8% of cases, leading to multiple myeloma (MM), monoclonal gammopathy of renal significance (MGRS), AL amyloidosis, and Waldenström macroglobulinemia (WM). The highest number of patients progressed to MM (6 patients) with an average time of 69.5 months. Patients in the intermediate-high-risk group were the most likely to progress to malignant hematologic disease (84.6%). Patients in the low- and intermediate-low-risk groups had a statistically significantly lower likelihood of progression (p = 0.004) compared to those in the intermediate-high- and high-risk groups. Compared to non-progressing patients, those with disease progression had significantly higher 24-hour proteinuria values (p = 0.003) and a higher prevalence of immunoparesis (23.1%, p = 0.003). The concentration of paraprotein (M protein) above 15 g/L was significantly more frequent among patients with progression (p = 0.03). Conclusion: Early identification of MGUS patients at intermediate-high and high risk is crucial in routine clinical practice to facilitate timely treatment decisions.