Monoclonal gammopathy from nephrology perspective

Abstract Multiple myeloma (MM) is characterised by the presence of a serum monoclonal spike (M-spike) exceeding 3 g/dL or more than 10% clonal plasma cells in the bone marrow, coupled with myeloma-defining events such as anaemia, hypercalcaemia, renal insufficiency or bony lesions. In contrast, monoclonal gammopathy of undetermined significance (MGUS) presents with lower thresholds for M-spike and plasma cell involvement and generally lacks myeloma-defining events. This case series highlights the relatively uncommon renal involvement in MGUS, which can manifest as monoclonal gammopathy of renal significance (MGRS). Five clinical cases illustrate the diagnostic challenges and therapeutic approaches associated with renal dysfunction in monoclonal gammopathies. These cases reveal the complexities of diagnosing MM and MGRS, particularly when renal failure is the primary presentation. The discussion emphasises the need for heightened clinical suspicion and comprehensive diagnostic workup, including renal biopsy, to elucidate the underlying pathology. The findings underscore the importance of identifying and treating the clonal plasma cell disorders contributing to renal complications, with various treatment regimens tailored according to disease severity and specific presentations. It concludes that early recognition of monoclonal gammopathy as a potential cause of renal failure is crucial for effective management and better patient outcomes.