Renal Involvement in Rheumatoid Arthritis: Analysis of 53 Renal Biopsies

Background: Rheumatoid arthritis (RA) is a systemic inflammatory disorder characterized by joint inflammation, associated with autoantibody production. Renal involvement arises as a complication of treatment or can be related to the disease itself. Methods: 53 biopsies from patients with RA from 1989 to 2015 were reviewed. Histologic diagnosis, age, gender, duration of RA, drug therapy, renal function, proteinuria and haematuria were analyzed. Results: Amyloidosis was the most common renal histologic pattern (21 patients). Membranous Nephropathy (MN) was found in 12 patients, followed by Mesangial Proliferative Glomerulonephritis (n=4) and Focal and Segmental Glomerulosclerosis (n=4), IgA Nephropathy (n=3), Necrotizing Glomerulonephritis (n=3), Chronic Interstitial Nephritis (n=3), Endocapillary Proliferative Glomerulonephritis (n=2) and Minimal Change Disease (n=1). Amyloidosis correlated with long duration RA (14.9±6.66 years vs 8.84±6.37 years; p<0.001), presenting with nephrotic proteinuria in the majority of the cases (5.11±2.94 g/24h vs 3.52±2.71 g/24h p=0.03), which correlates with dominant glomerular amyloid deposition (7.0±2.28 g/24h vs 3.04±2.08 g/24h; p<0.001). In patients with MN, renal function was preserved (serum creatinine 0.83±0.21mg/dl vs 2.03±0.21mg/dl; p