The Changing Pattern of Renal Amyloidosis in Indian Subcontinent: Two Decades of Experience from a Single Center

Background: Renal amyloidosis is a major cause of morbidity and mortality among the patients of systemic amyloidosis. The causes of amyloidosis vary from country to country and from time to time at individual center. Aim: This study investigates the changes in epidemiological and clinical profile of renal amyloidosis in recent years. Method: Cases of biopsy-proven renal amyloidosis from January 1992 to December 2010 were studied retrospectively. They were divided into two groups: 1990s (between 1992 and 2002) and 2000s (between 2003 and 2010). The clinical characteristics of patients were studied and compared between the groups. Result: A total of 2498 (974 in 1990s and 1524 in 2000s) renal biopsies was done during the 19-year period. The incidence of amyloidosis in 1990s and 2000s was 1.74% (n = 17) and 1.9% (n = 29), respectively (p > 0.05). We noted that the incidence of renal amyloidosis increased significantly (p < 0.05) among the females in 2000s. The mean age of patients in 2000s and 1990s was 38 +/- 17.9 and 39.2 +/- 19 years, respectively (p = 0.83). Renal insufficiency in patients with renal amyloidosis significantly increased (p < 0.05) in 2000s (n = 14; 48.2%) in comparison to 1990s (n = 2; 12.8%). Subnephrotic proteinuria was observed in 12.8% (n = 2) and 48.82% (n - 14) of patients in 1990s and 2000s, respectively (p < 0.05). Infection (n = 10; 58.8%) was the most common cause of secondary amyloidosis during the 1990s, whereas chronic inflammation (n = 14; 48.2%) was the most common cause in 2000s. In 1990s, the incidence of ankylosing spondylitis (AS) and rheumatoid arthritis (RA) was 11.7% (n = 2) and 5.8% (n = 1), respectively, but in 2000s, their respective incidence was 17.2% (n = 5) each. Multiple myeloma (MM) was the most common cause of amyloid light chain protein (AL) amyloidosis in both the groups. We observed systemic lupus erythromatosus (SLE)-related renal amyloidosis in two cases and Hodgkin lymphoma-associated amyloidosis in one case in 2000s. Conclusion: The overall incidence of renal amyloidosis showed little change from 1990s to 2000s. Chronic inflammatory diseases were the most common cause of renal amyloidosis in 2000s in contrast to infections in 1990s. Female gender was more affected in 2000s than in 1990s. Renal insufficiency and subnephrotic-range proteinuria were more frequent clinical manifestations of renal amyloidosis in recent years (2000s) in comparison to the earlier decade (1990s).