Urinary Findings in Renal Light Chain–Derived Amyloidosis and Light Chain Deposition Disease

BackgroundEarly recognition of light chain—derived (AL) amyloidosis and light chain deposition disease (LCDD) is essential for optimal therapy. However, clinical and laboratory manifestations of these unusual conditions often go unrecognized. Renal protein deposits in AL amyloidosis and LCDD can cause both heavy albuminuria and Bence Jones proteinuria. Absent separate etiologies, this combined finding is rare and provides a clue to the diagnosis of these conditions.Materials and MethodsWe retrospectively reviewed test results of urine immunoelectrophoreses and urine immunofixation electrophoreses performed at a single institution from 1977 to 2006. Patients with both heavy albuminuria and Bence Jones proteinuria were investigated further to determine whether these findings were predictive of renal AL amyloidosis or LCDD. We reviewed the patients' clinical histories, laboratory data, and pathology reports and included patients with biopsy-confirmed renal AL amyloidosis or LCDD in this series.ResultsWe identified 6 patients with renal amyloidosis or LCDD who presented with the dual findings of Bence Jones proteinuria and heavy albuminuria. We report their demographic information, laboratory data, and case histories.ConclusionThe simultaneous presence of heavy albuminuria and Bence Jones proteinuria justifies a workup for AL amyloidosis or LCDD. Prompt recognition of these rare conditions would permit earlier initiation of therapy and potentially limit organ dysfunction. In addition, patients might be spared unnecessary clinical investigation and unwarranted treatment.