[Renal Involvement in Connective Tissue Diseases]

Renal involvement is common and heterogenous in connective tissue diseases and has a main influence on prognosis and mortality. In systemic lupus erythematosus proliferative glomerulonephritis is the most common manifestation, while in primary Sjogren's syndrome interstitial nephritis with tubular dysfunction is the predominant pathological feature. In systemic sclerosis the most serious renal manifestation is scleroderma renal crisis characterized by abrupt onset of hypertension and acute kidney injury associated with an increase in plasma renin activity. Risk factors for scleroderma renal crisis are diffuse cutaneous involvement, treatment with corticosteroids > 15 mg prednisolone/day and treatment with calcineurin inhibitors.Regular measurement of urine sediment, proteinuria-to-urine creatinine ratio, tubular proteinuria, measurement of plasma creatinine, and office as well as home blood pressure monitoring are strongly recommended. Diagnostic kidney biopsy is essential in differentiating the different types of lupus nephritis and renal involvement in sjogren's syndrome.The optimal treatment of lupus nephritis varies with the classification of the morphological findings present on renal biopsy. The treatment of interstitial nephritis in sjogren's syndrome consists of immunosuppression e. g. corticosteroids. Renal tubular acidosis should be corrected by sodium alkali and potassium alkali. Angiotensin-converting enzyme inhibitors play a major role in the treatment of scleroderma renal crisis, they should be continued also in patients progressing to end-stage renal disease.