The patient with rheumatoid arthritis, mixed connective tissue disease, polymyositis, Sjögren syndrome , or overlap syndromes

Renal disease is a well-recognized cause of ill health and death in rheumatoid arthritis. Three broad categories of renal disease occur in such patients. The first—and by far the most common—arises from the nephrotoxicity of the drugs used in the treatment of arthritis, particularly with non-steroidal anti-inflammatory drugs. Disease- modifying anti-rheumatic drugs (DMARDs) such as gold and penicillamine may lead to proteinuria and a glomerulonephritis in 10– to 30% of patients. Ciclosporin has been extensively used in the treatment of patients with rheumatoid arthritis and is associated with significant nephrotoxicity and hypertension. Biological therapy is increasingly used to suppress disease activity. Data continues to be collected on its safety, although little renal toxicity is reported. A second major but diminishing cause of renal disease in rheumatoid arthritis RA is amyloidosis. Thirdly, there is now good evidence that rheumatoid arthritis RA may be associated with the development of a glomerulonephritis. The main types described are a mesangial proliferative glomerulonephritis with or without immunoglobulin A deposits, a membranous nephropathy, and a focal segmental necrotizing glomerulonephritis of the vasculitic type. Renal disease in mixed connective tissue disease and polymyositis is infrequent, but the former can be associated with a membranous and mesangial proliferative glomerulonephritis. Sjögren’s syndrome is rarely associated with clinically significant renal disease, but patients can present with proteinuria, acidosis, or hyperchloraemia. Interstitial nephritis and immune complex glomerulonephritis reflect the exocrinopathy and circulating immune complex disease pathognomonic of Sjögren’s syndrome. Evidence for effective treatment of the renal complications is lacking. Corticosteroids and cyclophosphamide are most commonly used, with newer biological drugs, such as rituximab, showing promise.