Monoclonal gammopathy of renal significance (MGRS): when MGUS is no longer undetermined or insignificant

Nelson Leung, Frank Bridoux, Colin A. Hutchison, Samih H. Nasr, Paul Cockwell, Jean-Paul Fermand, Angela Dispenzieri, Kevin W. Song and Robert A. Kyle


Multiple myeloma (MM) is the most frequent monoclonal gammopathy to involve the kidney; however, a growing number of kidney diseases associated with other monoclonal gammopathies are being recognized. Although many histopathologic patterns exist, they are all distinguished by the monoclonal immunoglobulin (or component) deposits. The hematologic disorder in these patients is more consistent with monoclonal gammopathy of undetermined significance (MGUS) than with MM. Unfortunately due to the limitations of the current diagnostic schema, they are frequently diagnosed as MGUS. Since treatment is not recommended for MGUS, appropriate treatment is commonly withheld. In addition to end stage renal disease and the persistence of the monoclonal gammopathy is associated with high rates of recurrence after kidney transplantation. Preservation and restoration of kidney function is possible upon successful treatment targeting the responsible clone. Achievement of hematologic complete response has been shown to prevent recurrence after kidney transplantation. There is a need for a term that properly conveys the pathologic nature of these diseases. We feel the term monoclonal gammopathy of renal significance (MGRS) is most helpful to indicate a causal relationship between the monoclonal gammopathy and the renal damage and since the significance of the monoclonal gammopathy is no longer undetermined.

  • Submitted July 26, 2012.
  • Accepted September 20, 2012.