A case of light-chain-type multiple myeloma in a hemodialysis patient that was diagnosed based on an elevated free light chain κ/λ ratio alone

Abstract

We report a case of light-chain-type multiple myeloma without serum M-protein in a hemodialysis patient. The patient was a 47-year-old male, who was found to have a serum creatinine level of 1.2 mg/dL, but exhibited no evidence of proteinuria or hematuria. A marked increase in his serum creatinine level (to 6.9 mg/dL) was noted 2 years later, and hemodialysis treatment was started. Left ventricular hypertrophy was diagnosed, and liver dysfunction together with hepatomegaly and splenomegaly were detected 2 months later. The patient gradually developed back pain, and a serum immunoglobulin free light chain (FLC) assay was performed. His κ/λ ratio was extremely high (68.23), and based on the results of a bone marrow biopsy, we made a definitive diagnosis of multiple myeloma. The serum M-protein, which is usually present in multiple myeloma, was not detected at any time. The immunoglobulin FLC κ/λ ratio assay was the key to diagnosing multiple myeloma in this case.