OBJECTIVES: We aimed to evaluate the hypothesis that chronic antigenic stimulation is an etiological factor of monoclonal gammopathy of undetermined significance (MGUS) with special relevance to Helicobacter pylori infection. METHODS: We performed a retrospective, observational study. The diagnosis of MGUS was based on serum protein electrophoresis, serum IgM levels (≤3 gr/dl), urinary M protein, a normal bone marrow biopsy, normal renal function, and a negative skeletal survey. H. pylori infection was ascertained by rapid urease testing and endoscopy with gastric biopsy for histology. Eradication of H. pylori was assessed by urea breath test and stool antigen assay 4 wk after completion of an appropriate treatment regimen. RESULTS: Sixty-nine patients with MGUS were included in the study. Of these, 57 had undergone evaluation for H. pylori infection for various GI symptoms. Thirty-nine of 57 patients (68.42%) with MGUS also had evidence of H. pylori infection. In 11 of these 39 patients (28.21%), eradication of H. pylori infection with an appropriate regimen led to normalization of the serum protein electrophoresis and resolution of the gammopathy. CONCLUSION: The results of our study give increased credibility to the theory that in a proportion of patients the pathogenesis of MGUS involves chronic antigenic stimulation and H. pylori is implicated. The search for H. pylori infection and an attempt to eradicate the bacterium in positive cases seem to be appropriate in patients diagnosed with MGUS.
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