Chronic interstitial nephritisrepresents a large and diverse group of disorders characterized primarily by interstitial fibrosis with mononuclear leukocyte infiltration and tubular atrophy (1-3). Thechronic damage is unrelated to underlying glomerular or vascular processes. Symptoms of interstitial nephritis Increased urine output. Blood in your urine or dark urine. Nausea or vomiting. Fever or rash. Elevated blood pressure. Changes in mental status, such as drowsiness or confusion. Swelling of any area of your body. Sudden weight gain (this can be caused by extra fluid in the body). Reference: GHAI Essential pediatrics, 8th edition