Recommendations for the study of monoclonal gammopathies in the clinical laboratory. A consensus of the Spanish society of laboratory medicine and the Spanish society of hematology and hemotherapy. Part III: clinical and analytical recommendations for the study of monoclonal gammopathies by MALDI-TOF mass spectrometry

Abstract Monoclonal gammopathies (MGs) represent a diverse group of plasma cell disorders that range from asymptomatic premalignant conditions to aggressive malignancies such as multiple myeloma (MM). Mass spectrometry (MS) based serum analysis offers a non-invasive, highly sensitive alternative to conventional techniques for identifying and quantifying M-proteins. It enables more precise assessment of treatment response and residual disease, particularly in patients with suspected complete response (CR), those not eligible for bone marrow procedures, or those treated with monoclonal antibodies that may interfere with standard assays. This guideline document, endorsed by the Spanish Society of Laboratory Medicine (SEMEDLAB) and the Spanish Society of Hematology (SEHH), provides comprehensive recommendations for the clinical and analytical application of MS in the detection and monitoring of M-proteins in patients with MGs. The document outlines optimal use of MS at diagnosis, during follow-up, and in reporting practices, with a focus on standardized implementation, interpretative criteria, and clinical decision-making support.