Abstract: A 43-year-old man presented with recurrent creatinine elevation for one year. The clinical manifestations were proteinuria and renal damage, accompanied with Fanconi syndrome. Immunofixation electrophoresis indicated kappa light chain band in blood and urine,and the ratio of κ/λ was significantly increased. Renal biopsy pathology revealed acute tubular injury. Immunoelectron microscopy show monoclonal kappa light chain crystals deposited in renal tubular cytoplasm. The final diagnosis was light chain proximal tubulopathy (crystalline type).

Key words: light chain proximal tubulopathy, Fanconi syndrome, acute tubular injury, monoclonal gammopathy of renal significance, renal tubular acidosis