Chronic interstitial nephritis is a nonspecific diagnosis of a pattern of kidney injury, which may occur due to any of many conditions that initially cause an acute interstitial nephritis. The diagnosis is made when specific underlying causes cannot be identified. Patients may present at any age, usually with low-grade proteinuria and slowly progressive decline in glomerular filtration rate, and may reach end-stage kidney disease. Fanconi syndrome may be present, with glycosuria and aminoaciduria.