Prevalence of Monoclonal Gammopathy in Newly Diagnosed Osteopenia and Osteoporosis: Findings from a Prospective DXA Clinic Cohort

Study Objective: To ascertain the prevalence of monoclonal gammopathy in an inception cohort of patients with low bone mineral density. Design: We conducted a prospective cohort study of 115 patients (median age 69 [47–90]; 102 female) who were newly diagnosed (January-June 2022) with osteopenia (47% of cohort) or osteoporosis (OP) (53%) from the DXA clinic. Screening comprised serum protein electrophoresis (SPEP), serum free light-chain assay (sFLC), and urine Bence Jones protein testing (uBJP). Results were available for 109, 108, and 96 participants, respectively. Participants with prior diagnosis of low bone density or monoclonal gammopathy were excluded. Results: 59% of the cohort had a history of fragility fracture. Monoclonal proteins were detected in 2 out of 115 patients (1.7%) with abnormal sFLC results in both cases. One patient’s work-up revealed multiple myeloma, and another patient was diagnosed with a low-grade B-cell non-Hodgkin lymphoma. No cases of MGUS were identified in this cohort. Conclusion: Among 115 newly diagnosed osteopenia/OP patients, the prevalence of underlying monoclonal gammopathy was low (1.7%). We identified isolated cases of multiple myeloma and an indolent B-cell lymphoma, but no MGUS, in this sample. These findings illustrate that while routine screening of all low bone density patients will yield few positives, it can uncover serious but treatable haematologic conditions in a minority. The study also highlights the value of using a combination of tests (serum electrophoresis plus free light-chain and urine protein assays) to improve detection of monoclonal gammopathies in patients with low bone density.