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Reversible renal failure due to isolated renal sarcoidosis.

Renal impairment in sarcoidosis is usually due to hypercalcaemia and nephrocalcinosis but can also be caused by granulomatous nephritis or interstitial nephritis without sarcoid granulomata. A variety of types of glomerulonephritis have also been described in sarcoidosis but these rarely cause impaired renal function. Renal failure as an isolated manifestation of sarcoidosis is uncommon. A 66-year-old woman presented with a 1-year history of lethargy, polyuria and nocturia. Clinical examination was unremarkable and she had impaired renal function (urea 18 mmol/l (108 mg%) and creatinine 380 mumol/l (4.3 mg%)). As her kidneys were normal in size, she underwent renal biopsy, which revealed granulomatous interstitial nephritis. Reevaluation showed no other evidence of sarcoidosis and she had impaired urinary acidification and concentrating capacities. Therapy with corticosteroids produced a marked improvement in symptoms and renal function. This case confirms the view that granulomatous sarcoid nephritis is steroid sensitive and that full recovery can be expected provided interstitial fibrosis and scarring do not occur.