Isolated renal relapse of sarcoidosis under low-dose glucocorticoid therapy.

Sarcoidosis is a multisystem disease of unknown etiology. Renal manifestation is rare and usually caused by hypercalcemia and nephrocalcinosis. Moreover, renal disease can occur as granulomatous interstitial nephritis (GIN), which is a histological diagnosis. We describe a case of sarcoidosis first presenting with multiple organ involvement including renal failure caused by severe GIN and subsequent remission on glucocorticoid therapy. After 18 months under low-dose prednisolone, the patient was readmitted with acute renal failure, histologically confirmed to be a relapse of renal sarcoidosis. Extrarenal manifestations of sarcoidosis were not present. Glucocorticoid dose was raised and kidney function again recovered significantly. Usual serologic markers of disease activity were not appropriate to indicate disease activity. Renal manifestation of sarcoidosis should be diagnosed by renal biopsy to guide therapy and probably requires larger glucocorticoid doses and prolonged treatment to prevent relapse.