Incidence and clinical outcome of renal amyloidosis: A retrospective study

Abstract

The kidneys are affected in almost all patients with amyloid A in secondary amyloidosis (AA) amyloidosis but less frequently in immunoglobulin light chains in primary systemic amyloidosis (AL) amyloidosis. In this study, we present the incidence, etiology, clinical manifestations, biochemical features and clinical course of renal amyloidosis. We conducted a retrospective study on a group of 40 cases with renal biopsy-proven amyloidosis. They constituted 2.5% of the total cases of renal biopsies performed in the Theodor Bilharz Research Institute, Cairo, Egypt, during the period from February 2003 to May 2009. The mean age (30 males, ten females) was 36.51 ± 10.32 years. Thirty-two of the cases had secondary AA amyloidosis and eight cases had primary AL amyloidosis. The causes of secondary amyloidosis were as follows: 12 (30%) familial Mediterranean fever (FMF), eight (20%) pulmonary tuberculosis, four (10%) chronic osteomyelitis, four (10%) bronchiectasis, three (7%) rheumatoid arthritis and one (2%) rheumatic heart disease. The eight cases of primary AL amyloidosis comprised of five cases that were associated with myloma (13%) and three (8%) cases that were idiopathic. Among the 23 patients with AA amyloidosis, after six months of treatment with colchicine, the proteinuria improved, serum albumin level increased and edema disappeared in 13 patients. In four cases of AA amyloidosis who were clinically and biochemically normal after cholchicine therapy, a second renal biopsy disclosed decreased amyloid deposition compared with the first biopsy. In the three renal transplanted patients who had amyloidosis secondary to FMF and were treated with colchicines, AA amyloidosis did not recur in the transplanted kidney. It might be possible that in AL amyloidosis, treatment with methotrexate, melphalan and prednisolone may improve survival. The incidence of renal amyloidosis is increasing and colchicine can be used in secondary amyloidosis as it may have an effect on reducing the production of the amyloid precursor proteins and in reducing proteinuria.