[Idiopathic chronic tubulointerstitial nephritis]

Chronic tubulointerstitial nephritis is a chronic disorder that primarily affects the renal tubules and interstitium while sparing the glomeruli and vasculature. Although there are variable underlying causes, 10% to 25% of the cases of chronic tubulointerstitial nephritis are entirely idiopathic. A thorough search for the underlying causes of chronic tubulointerstitial nephritis is especially important because to avoid or to correct such underlying causes may prevent progression or even allow for some reversal of renal failure. Thus, diagnosis of idiopathic form of chronic tubulointerstitial nephritis is carefully made after the exclusion of potential underlying causes. The major pathologic features of idiopathic chronic tubulointerstitial nephritis are 1) interstitial fibrosis, 2) tubular atrophy and 3) infiltration of the parenchyma with mononuclear inflammatory cells. Of these three features, the extent of interstitial fibrosis is significantly correlated with decreased glomerular filtration rate and progression rate of renal failure. Idiopathic chronic tubulointerstitial nephritis seems to be slowly progressive and develop to end stage renal failure. Since there is no specific treatment for idiopathic chronic tubulointerstitial nephritis, avoidance and correction of exacerbation factors are essential for progression to renal failure. It is acceptable that protein-restricted diet be applied to idiopathic chronic tubulointerstitial nephritis although its effects on the disease still remain equivocal.