[Interstitial nephritis in rheumatic diseases].

Interstitial nephritis is responsible for about 12 % of end-stage renal disease in Germany. It comprises an etiologically heterogenous group of inflammatory renal disorders which primarily affect the renal interstitium and tubuli. Drugs, predominantly antibiotics, nonsteroidal anti-inflammatory drugs and proton pump inhibitors are causative in the majority of cases. Rheumatic diseases frequently affect the kidneys, either the glomeruli or the interstitial tissues. Inflammatory interstitial processes can be accompanied by complex functional tubular disorders. This review gives an overview about clinical and laboratory findings of interstitial nephritis in the context of rheumatic diseases. Sarcoidosis, tubulointerstitial nephritis and uveitis (TINU) syndrome, primary Sjogren's syndrome, and IgG4-related disease often show an interstitial nephritis when the kidneys are affected. Other diseases, such as systemic lupus erythematosus, systemic sclerosis, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, and granulomatosis with polyangiitis are more rarely associated with predominant interstitial nephritis. Glucocorticoids are the mainstay of therapy for most cases; in refractory cases or when side effects occur, second-line immunosuppressants such as mycophenolate mofetil, azathioprine and others, rarely biologics, can be used.