A new term, “monoclonal gammopathy of renal significance (MGRS)” was proposed by Leung and colleagues  to describe a group of haematological disorders associated with kidney disease that fail to meet the standard definitions for MM or lymphoma. In such cases, the renal impairment is often linked to the underlying haematological disorder. Their definition included AL amyloidosis (Chapter 28), type I and II cryoglobulinaemias (Section 34.2), monoclonal immunoglobulin deposition disease (MIDD; Chapter 29) and Fanconi syndrome . The intention was to make a clear distinction between MGUS (Chapter 13), a benign asymptomatic condition, and MGRS, which may be associated with significant morbidity and mortality. Supportive information was published by two studies: Steiner et al.  studied the long-term outcome of MGRS patients compared to MGUS patients without renal impairment, and concluded that MGRS patients had a significantly higher risk of progression to MM. Johnson et al.  reviewed data from 425 patients with MGUS, and found that an abnormal sFLC ratio and elevated involved sFLC concentrations were associated with an increased risk of developing renal disease. Yadav et al.  and Correia et al.  recommend the use of sFLC analysis when screening for MGRS.