[Expert consensus for the diagnosis and treatment of patients with renal impairment of multiple myeloma].

Renal impairment (RI) is a common complication of multiple myeloma (MM), which is presented as chronic kidney disease (CKD) or acute kidney injury (AKI). The typical pathological feature is cast nephropathy. Presently international system staging (ISS) is used in evaluating MM. Although the classic Durie-Salmon staging system could be still used in clinical practice, it may miss out some patients with renal impairment. For evaluations of RI in MM patients with CKD, it's recommended to assess the estimated glomerular filtration rate (eGFR) by creatinine based formula CKD-epidemiology collaboration (EPI) or modification of diet in renal disease(MDRD) and to stage the renal injuries according to 2013 Kidney Disease Improving Global Outcomes (KDIGO) CKD guidelines. For MM patients with AKI, KDIGO AKI guidelines is recommended for evaluation. Renal biopsy is not a routine procedure in all MM patients. It's necessary for patients presenting with glomerular injuries such as albuminuria > 1 g/24 h to eliminate immunoglobulin associated amyloidosis (AL) and monoclonal immunoglobulin deposition disease (MIDD). The effective treatment of MM can reduce serum light chain concentration and improve renal function. The basis of the RI treatment in MM is bortizomib-based regimen, which does not require dosage adjustment in patients with dialysis or renal insufficiency. Thalidomide and lenalidomide are two major immunomodulators in MM treatment. Thalidomide can be used effectively in RI patients without dosage adjustment while lenalidomide should be used cautiously in patients with mild or moderate RI with dosage adjustment and serum toxicity surveillance. High-dose therapy (HDT) and autologous peripheral blood stem cell transplantation (APBSCT) can be therapeutical options for RI patients younger than 65 y, and they should be considered more prudently in patients with severe renal insufficiency (GFR<30 ml/min). For patients who are not suitable for the treatment mentioned above, they can be treated with conventional chemotherapy, including VAD (vincristine, adriamycin and dexamethasone), MP (mephalan and prednisolone) and high-dose dexamethasone regimen. Adequate hydration (at least 3 litres of fluid intake a day or 2 L·m(-2)·d(-1)) and correcting reversible causes of RI are key points for the supportive care. Renal replacement therapy (more often hemodialysis) should be started in patients with severe AKI and end stage renal disease (ESRD). High flux or high cut-off membrane are recommended because routine hemodialysis could not remove the serum free light chain (sFLC) effectively. Plasmapheresis (PE) is recommended for patients with hyperviscosity syndrome or cast nephropathy presented with AKI, which may help to increase the dialysis-independency.