Interstitial nephritis is also called tubulointerstitial nephritis. It is a clinicopathological syndrome of acute and chronic tubulointerstitial damage caused by various reasons. Interstitial nephritis protein belongs to tubulointerstitial proteinuria. Renal tubular dysfunction may be accompanied by low specific gravity hypotonic urine, renal tubular proteinuria and disturbance of water, electrolyte and acid-base balance, and some patients show Fanconi syndrome.