Clinically important renal involvement occasionally occurs in sarcoidosis. Renal manifestations include abnormal calcium metabolism, nephrolithiasis and nephrocalcinosis, and acute interstitial nephritis with or without granuloma formation. The classic renal lesion is noncaseating granulomatous interstitial nephritis. However, this lesion rarely causes clinically significant renal disease. Hypercalciuria and hypercalcemia are most often responsible for clinically significant renal disease. Glomerular disease, obstructive uropathy, and end-stage renal disease (ESRD) may also occur, but are uncommon [1,2].
The renal manifestations of sarcoidosis will be reviewed here. General issues related to sarcoidosis and its pathogenesis are discussed separately. (See "Clinical manifestations and diagnosis of pulmonary sarcoidosis" and "Pathogenesis of sarcoidosis".)
The incidence and prevalence of renal involvement in sarcoidosis remain uncertain .
The reported prevalence ranges widely due to the enormous variation in study design and enrolled patient populations, and due to the heterogeneity and often asymptomatic nature of renal disease.
Several small series have suggested that renal involvement (as defined by either histologic changes in the kidney or a decline in renal function in the absence of a biopsy) occurs in approximately 35 to 50 percent of patients [4-7], even if, in most cases, the disease may be silent and undetected for many years or forever. In one study, among 46 patients with acute or chronic sarcoidosis, 15 patients had renal abnormalities .