Renal manifestation in patients with rheumatoid arthritis

Park, Su Kyoung; Lee, Young Chul; Kim, Jee Hyun; Park, Joon Sung; Lee, Chang Hwa; Bae, Sang Cheol; Yoo, Dae Hyun; Kang, Chong Myung; Kim, Gheun Ho

Abstract

BACKGROUND/AIMS: Although renal manifestations are often involved in patients with rheumatoid arthritis (RA), the causal relationship between RA and renal manifestations has not been clearly defined. The prevalence and causes of renal manifestations in patients with RA were investigated in this study.
METHODS
The clinical data from 457 patients with RA and who were admitted to Hanyang University Hospital between 2001 and 2005 were retrospectively analyzed. Renal manifestations were defined as proteinuria (> or =300 mg/day) or azotemia (serum creatinine > or =1.7 mg/dL), with or without hematuria.
RESULTS
Renal manifestation was present in 82 (17.9%) out of 457 RA patients. Among them, proteinuria was observed in 81 (17.7%), azotemia in 37 (8.1%) and hematuria with either proteinuria or azotemia in 35 (7.7%). For the cases with proteinuria, the amount of preteinuria was 1353+/-207 (mean+/-SD) mg/day. There was no significant correlation between the degree of proteinuria and the duration of RA. For the cases with azotemia, the serum creatinine was 3.98+/-0.35 mg/dL. The presence of azotemia had no significant association with the duration of RA (14.4+/-1.5 vs. 11.6+/-1.2 years, respectively). When the etiology of the renal manifestation was classified into primary and secondary renal disease, the latter included diabetic nephropathy in 13 (15.9%), hypertensive nephrosclerosis in 8 (9.8%), drug induced chronic tubulointerstitial disease in 11 (13.4%) and AA amyloidosis in 2. Renal biopsy revealed 10 cases of primary glomerulopathy, including IgA nephropathy in 3, membranous nephropathy in 2, mesangial proliferative glomerulonephritis in 1, focal segmental glomerulosclerosis in 1 and chronic sclerosing glomerulonephritis in 3.
CONCLUSIONS
The prevalence of chronic kidney disease in patients with RA is high, although direct renal invasion by RA is very rarely encountered. Renal biopsy would be of great help to identify the various causes of renal manifestations in patients with RA.