Interstitial Nephritis

Abstract

Although primary glomerular diseases such as glomerulonephritis frequently have associated secondary interstitial lesions, it is necessary to distinguish them from cases where there is no primary glomerular damage and the pathological changes affect predominantly the tubules and interstitium. For this purpose, the description ‘interstitial nephritis’ is used, and although it includes a variety of different diseases of known and unknown aetiology, the breadth of the term has some merits. A label of ‘interstitial nephritis’ prompts careful evaluation of all the relevant clinical and pathological aspects before a more precise diagnosis is attempted. Microscopically, interstitial nephritides are principally characterized by changes in the interstitium (oedema and/or fibrosis, often with inflammatory cell infiltration) and the tubules (tubular atrophy and loss). These lesions may result from direct damage to tubules or interstitium, orfrom vascular insufficiency. Sometimes a combination of factors is involved and frequently the exact mechanisms are obscure.