The kidney in rheumatological disorders

Abstract

Many rheumatological conditions have systemic effects. Antibody production, complement activation, and protein deposition can all result in damage to the kidney, sometimes with devastating sequelae. Systemic lupus erythematosus—lupus nephritis is clinically evident in up to 75% of patients with systemic lupus erythematosus (SLE), and endstage renal disease is seen in 5 to 10% of patients at 10 years. Proteinuria is the most common clinical presentation, closely followed by nonvisible haematuria and tubular abnormalities. Patients with active lupus nephritis often have features of active SLE. The gold standard for lupus nephritis diagnosis is a renal biopsy, with treatment related to histopathological features observed. Adjunctive immunosuppressive agents such as rituximab and tacrolimus are emerging as increasingly important lupus nephritis therapies. Systemic sclerosis is a multiorgan connective tissue disease. Most renal manifestations are clinically silent. By contrast, the scleroderma renal crisis is characterized by accelerated-phase hypertension and impaired renal function. It carries a high mortality risk. Rheumatoid arthritis can affect the kidneys in many ways, most commonly by causing amyloid A amyloidosis. This presents with proteinuria, often severe enough to cause nephrotic syndrome, with 50% progressing to endstage renal failure after 5 years (90% at 10 years). Renal vasculitis, mesangiocapillary glomerulonephritis, and mesangial IgA proliferative glomerulonephritis are also described. Gold and penicillamine (now rarely used) can cause proteinuria, sometimes with nephrotic syndrome. Renal involvement in Sjögren’s syndrome is generally mild, but up to a quarter of patients develop acute or chronic kidney disease, typically with evidence of tubular dysfunction. Glomerular abnormalities are rare and the most common histological abnormality is tubulointerstitial nephritis. Drug nephrotoxicity—conventional antirheumatics and over-the-counter nonsteroidal anti-inflammatory drugs are used exceptionally widely in the community and are nephrotoxic. Their almost ubiquitous use, especially during intercurrent illnesses, means they are frequent contributors to acute and chronic kidney damage.