The Pathophysiology of Kidney Involvement in Multiple Myeloma and Monoclonal-Related Disorders

Multiple myeloma (MM) is the most common malignancy associated with end-stage renal disease; the presence of renal involvement reduces the median survival of patients with MM. Recently the term “monoclonal gammopathy of renal significance” (MGRS) has been defined that describes all B cell or plasma cell proliferative disorders that produce a monoclonal immunoglobulin associated with progressive kidney injury. The excessive amount of clonal light chains is completely filtered and adsorbed till the maximum capacity of proximal tubule that could be saturated, so the excess of FLC presents in the urine as Bence Jones proteinuria. The different biochemical characteristics of FLC determine a different histological involvement, which imply the variable clinical presentation ranging from severe acute kidney injury to chronic renal failure with different grade of proteinuria. Actual therapies are directed to prompt FLC removal from circulation by apheresis and control of their production by proteasome inhibitors and the immunomodulatory drugs used in MM. They are needed to prevent progression of the renal involvement and improve renal prognosis.