TOPIC DISCUSSION: Rheumatoid Arthritis and the Kidney

Kidney disease in Rheumatoid Arthritis(RA) is not uncommon.  Clinical usually seen with isolated proteinuria, hematuria or both and chronic renal dysfunction as well.  Studies have shown that if kidney disease is involved, morbidity and mortality is worse.
Pathogenesis:
1. Immunologic disease:- Non immune complex mediated, immune complex mediated, or pauce immune crescentic GN.
              - Immune complex is usually 29% of the diseases, followed by Crescentic GN
              - The most common immune complex disease is Membranous GN, Ig A and mesangial GN( usually IgM mediated as RF is IgM)
              - Crescentic GN is usually pauce immune ANCA( p ANCA positive), older patients and can be also seen with Anti TNF agents

2. Drug induced:- NSAIDS, Gold, other DMARDS, Anti TNF alpha agents induced disease
                 - Very important class that can lead to interstitial damage, tubular damage, vascular damage, TMA and GNs.
3. AA Amyloidosis
                 - very hard to treat.  Predictor of mortality in RA.

Ref:
http://www.ncbi.nlm.nih.gov/pubmed/21245821
http://www.ncbi.nlm.nih.gov/pubmed/20617355
http://www.ncbi.nlm.nih.gov/pubmed/20954306