Objective: To evaluate renal biopsy findings and clinicopathologic correlations in patients with rheumatoid arthritis (RA).
Methods: Retrospective study of renal biopsy specimens from 110 RA patients in whom the clinical renal disease was probably due to RA itself and/or to antirheumatic therapy.
Results: The most common histopathologic finding was mesangial glomerulonephritis (GN) (n = 40), followed by amyloidosis (n = 33), membranous GN (n = 19), focal proliferative GN (n = 4), minimal-change nephropathy (n = 3), and acute interstitial nephritis (n = 1). Amyloidosis was the most common finding in patients with the nephrotic syndrome. In patients with isolated proteinuria, amyloidosis, membranous GN, and mesangial GN were almost equally common. Although mesangial GN was found in almost two-thirds of the RA patients with hematuria (with or without proteinuria), there still remained a 1 in 5 chance that the biopsy would reveal membranous GN or amyloidosis. Membranous GN was closely related to gold or D-penicillamine therapies, whereas mesangial GN probably related to RA itself.
Conclusion: The renal morphologic lesion in RA patients with isolated proteinuria and those with hematuria cannot be accurately predicted on the basis of clinical symptoms and signs. Biopsy is thus useful in differential diagnosis, assessment of prognosis, and decision-making with regard to treatment.