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.