25.3.7. Recommendations for the diagnosis and management of myeloma-related renal impairment (2016)

Chapter 25
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For the diagnosis of renal impairment in patients with MM, the IMWG recommend that all patients (at diagnosis and at disease assessment) have serum creatinine and electrolytes measurements, as well as sFLC analysis and 24-hour urine electrophoresis [859].

The IMWG recommendations also discuss the use of quantitative sFLC values in the evaluation of renal impairment in MM: if a patient has high sFLCs (defined as a concentration above a specified range of values [500 - 1500 mg/L]) and proteinuria (in which light chains predominate), then a diagnosis of cast nephropathy is likely and a renal biopsy is probably not necessary (but may be helpful in selective cases). If a patient has relatively low sFLCs (<500 mg/L) and non-selective proteinuria/significant albuminuria, then an alternative diagnosis (e.g. MIDD or AL amyloidosis) should be considered and a renal biopsy is often necessary.