Granulomatous sarcoid nephritis: a cause of multiple renal tubular abnormalities

We report the eleventh case of granulomatous sarcoid nephritis and review the previous literature. Although not as commonly recognized as calcium nephropath, granulomatous nephritis may be an important cause of morbidity and mortality in patients with sarcoidosis. Its characteristics are similar to other tubulo-interstitial diseases. Mild to moderate albuminuria, microscopic hematuria and sterile pyuria predominate. Hypertension is usually absent and renal size is well preserved. Urinary concentration defects (including nephrogenic diabetes insipidus), renal tubular acidosis and inappropriate glucosuria may also be seen. Interstitial inflammation with non-caseating granulomas, epithelioid and multinucleated giant cells is the usual histologic picture. Intimal thickening is not infrequent and granulomas may occasionally involve the small arteries. Immunofluorescence and electron microscopic findings are non-specific.