Chronic nephritis

Interstitial nephritis, also known as tubulointerstitial nephritis, is inflammation of the area of the kidney known as the renal interstitium, which consists of a collection of cells, extracellular matrix, and fluid surrounding the renal tubules. In addition to providing a scaffolding support for the tubular architecture, the interstitium has been shown to participate in the fluid and electrolyte exchange as well as endocrine functions of the kidney.There are a variety of known factors that can provoke the inflammatory process within the renal interstitium, including pharmacologic, environmental, infectious and systemic disease contributors. [Source: Wikipedia ]

May Cause
Small kidney