Rapid reduction of extremely high kappa free light chains in a patient with myeloma cast nephropathy.

This report describes a patient with light chain myeloma and acute renal injury. Serum kappa free light chain (FLC) was extremely elevated, >33,000 mg/dL. Treatment with therapeutic plasma exchange (TPE) started day 2 for biopsy-confirmed cast nephropathy. Bortezomib-containing chemotherapy was initiated on day 5, and hemodialysis for tumor lysis syndrome on day 7. TPE alone decreased kappa FLC >70% by day 5, indicating direct FLC removal was successful in this patient. A total of 25 TPE procedures were performed in a 31-day hospitalization. Hemodialysis was discontinued after 3 months, and the patient's renal function and kappa FLC remain stable. Although the use of TPE for FLC removal is controversial, recent evidence supports its use as adjuvant therapy for acute renal injury secondary to myeloma cast nephropathy. TPE can be effective for rapidly reducing FLC; however, several TPE procedures might be required to reduce the risk of hemodialysis dependency.