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Chronic tubulointerstitial nephritis (CTIN) is an inflammatory process that involves the peritubular space or interstitium of the kidneys resulting in interstitial scarring with fibrosis, a lymphomonocytic infiltrate, tubular dilation, and atrophy. These forms of injury are very similar regardless of the inciting cause. Usually asymptomatic, it presents as a slowly progressive impairment in renal function leading to chronic kidney disease (CKD). Any structural damage, either glomerular, tubular, or a direct injury to the interstitium from an acute nephritis that has not appropriately resolved can amount to CTIN.
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The most common etiologies are medication-induced lesions and infections. However, a wide variety of other diseases can lead to CTIN, including heavy metal toxicities or exposures, chronic obstructive nephropathy, reflux disease, nephrolithiasis, immunologic disease, metabolic disorders, genetic disease, neoplasia, and chronic renovascular, ischemia (Table 38–1). The following will provide an overview of select causes of CTIN.
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ESSENTIALS OF DIAGNOSIS Analgesic Nephropathy
Most common cause of drug induced CTIN
Seen with phenacetin, acetaminophen, aspirin, and NSAIDs
Presents with CTIN, papillary necrosis, hypertension
Despite association with nephropathy, number of patients is relatively low given the total amount of non-narcotic analgesics prescribed or available without prescription
Lithium-Induced Renal Disease Approximately 15–20% of patients treated with lithium will develop kidney disease
Latent period to development of ESRD is approximately 20 years
Renal manifestations include: FSGS, MCD, distal RTA, diabetes insipidus, and CTIN
Stopping lithium may delay progression, but progression to ESRD tends to occur if serum creatinine >2.5 mg/dL
Aristolochic Acid Nephropathy Exposure through herbal supplements containing ingredients from Aristolochia species
Rapid progression to ESRD of approximately 2 years
Biopsy reveals hypocellular infiltrate with severe fibrosis
40–45% prevalence of urothelial carcinomas
Treatment with glucocorticoids may delay progression to ESRD
Balkan endemic nephropathy is a prolonged variant of AAN with progression to ESRD occurring over decades
Renal Sarcoidosis Immune mediated disease affecting several organs including lungs and kidney
Renal involvement can be in the form of hypercalcemia with AKI to CTIN with granulomatous lesions
Glucocorticoids remains first line of therapy
TINU