Introduction:

Rheumatoid arthritis is one of the most common clinical syndromes within rheumatological conditions and its association with glomerular diseases is rare.

Objective:

To describe the histopathological findings in renal biopsies in patients with rheumatoid arthritis and to correlate them with the clinical and laboratory manifestations at the beginning, at 6 months and at one year of follow-up.

Patients and Methods:

This is a retrospective observational study conducted in the Hospital de Clinicas "Jose De San Martin" in Buenos Aires, Argentina; Where we included 41 patients diagnosed with RA (ACR 1987) in a period of 20 years. Histopathological diagnoses of membranous nephropathy (MN), minimal change disease (MCD), secondary amyloidosis (AA), focal and segmental glomerulosclerosis (FSGS); mesangial glomerulopathy (MGP) and glomerulonephritis with extracapillary proliferation (GNEC) were included. Histopathological description, different treatments, years of evolution of rheumatoid arthritis Clinical and laboratory characteristics were analyzed during the first 6 months and one year of follow-up in order to determine the progression of renal failure calculated through the formula of MDRD of 4 variables (Modification of diet in renal disease) and the increase of proteinuria.

Results:

The most frequent histological finding was amyloidosis with 34,1 % (n=14), followed by mesangial glomerulopathy 21,9 % (n=9), membranous nephropathy 19,5 % (n=8), glomerulonephritis with extracapillary proliferation 12,1 % (n=5), focal and segmental glomerulosclerosis 7,3 % (n=3) and minimal change disease 8,2 % (n=2). Nephrotic syndrome was the most frequent presentation in patients with amyloidosis in 85,7 %, microhematuria occurred in 100 % of patients with MPG and in 80 % of patients with GNEC. In patients with AA, moderate to severe interstitial fibrosis occurred in 85,7 %, followed by GNEC and NM with 80 % and 40 % respectively. The 24-hour proteinuria, creatinine and glomerular filtration rate estimated by MDRD at 6 months and 12 months were evaluated. Concluding, that patients with AA, FSGS and GNEC had greater progression of renal failure at 12 months; the opposite occurred in patients with minimal change disease (MCD) and mesangial glomerulopathy (MGP) who had a lower progression of renal failure at one year of follow-up; There was a correlation in the glomerulopathies that had greater deterioration of the renal function had greater interstitial tubule involvement as was the case of amyloidosis. The glomerulopathies that presented greater proteinuria at the beginning were membranous nephropathy, amyloidosis and minimal change disease. Both membranous nephropathy and minimal change disease had partial remission at one year, in contrast to amyloidosis, which showed progression of proteinuria at 12 months of follow-up.

Conclusion:

The glomerulopathies that presented greater progression of renal failure at 1 year based on the estimation by MDRD 4, had a higher renal tubular interstitial involvement in renal biopsy and these were amyloidosis (AA), segmental focal glomerulosclerosis (FSGS), glomerulonephritis with proliferation extracapillary On the other hand, those with the best evolution in relation to the degree of proteinuria and the glomerular filtration rate determined by the MDRD4 equation were mesangial glomerulopathy, minimal change disease, and membranous nephropathy.

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