[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Acute interstitial nephritis [Conditions](https://durgical.com/en/conditions/) · [Nephrology and urology](https://durgical.com/en/conditions/) # Acute interstitial nephritis Acute interstitial nephritis is inflammation around the kidney tubules, usually an allergic reaction to a medicine, and a reversible cause of kidney injury. Updated 2026-11-01 ## Structures involved Tap one to see what it is and open it in 3D. - [Kidneys](https://durgical.com/en/anatomy/kidney/) - [Vessels inside the kidney](https://durgical.com/en/anatomy/intrarenal-arteries-and-veins/) ## Why it happens - [Injury by therapeutic drugs: the classic examples](https://durgical.com/en/general-pathology/injury-by-therapeutic-drugs-the-classic-examples/) - [Innate and adaptive immunity: overview](https://durgical.com/en/physiology/innate-and-adaptive-immunity-overview/) - [Physiology of acute and chronic kidney failure](https://durgical.com/en/physiology/physiology-of-acute-and-chronic-kidney-failure/) - [Kidney: cortex, medulla and the nephron](https://durgical.com/en/histology/kidney-cortex-medulla-and-the-nephron/) ## What it is Inflammation and swelling of the renal interstitium and tubules, most often an allergic (hypersensitivity) reaction to a drug, that causes acute kidney injury. It accounts for a notable share of unexplained acute kidney injury in hospitalised patients. ## Who gets it It is found in about 10–15% of kidney biopsies done for acute kidney injury. Drugs cause about two thirds or more of cases, and it is more common in older adults taking several medicines. Infection-related and autoimmune forms are also seen; in Latin America, leptospirosis and other infections are additional causes to consider. ## Causes - Drugs (most cases): beta-lactam antibiotics, sulfonamides, fluoroquinolones, rifampicin, NSAIDs, proton pump inhibitors, allopurinol, diuretics, immune checkpoint inhibitors - Infections: bacterial (streptococci, Legionella, leptospirosis), viral (CMV, EBV, hantavirus), tuberculosis - Systemic disease: sarcoidosis, Sjögren disease, lupus, IgG4-related disease - TINU syndrome (tubulointerstitial nephritis with uveitis) ## Risk factors - Older age and multiple medications - Recent start of a new antibiotic, NSAID or proton pump inhibitor - Prior reaction to the same drug class - Autoimmune or granulomatous disease ## Pathophysiology A drug or its metabolite binds to tubular components or acts as a hapten and triggers a T-cell–mediated immune reaction. Lymphocytes, macrophages and often eosinophils infiltrate the interstitium, causing oedema and tubulitis that reduce filtration and tubular function. If the trigger persists, inflammation evolves to interstitial fibrosis and tubular atrophy with permanent loss of function. ## Classification - By cause: drug-induced, infection-related, autoimmune or systemic, idiopathic - Acute versus chronic tubulointerstitial nephritis ## Symptoms and signs - Often non-specific: malaise, nausea, rise in creatinine found on routine tests - Fever - [Skin](https://durgical.com/en/anatomy/skin/) rash - Joint pain - Flank pain from swollen kidneys - Change in urine output (often normal, sometimes reduced) - The classic triad of fever, rash and eosinophilia occurs in only a minority ## Red flags - Rapidly rising creatinine or very low urine output - Severe hyperkalaemia or metabolic acidosis - Rash with fever, facial swelling and organ involvement (DRESS) - Fluid overload with breathlessness ## Diagnosis **Clinical** Acute [kidney](https://durgical.com/en/anatomy/kidney/) injury days to weeks after starting a drug (it can appear months later with NSAIDs or proton pump inhibitors); detailed medication history. **Tests** Rising creatinine; urinalysis with sterile pyuria, white cell casts, mild proteinuria and sometimes haematuria; peripheral eosinophilia in some; urine eosinophils are of limited value. Kidney biopsy confirms interstitial inflammation and oedema with tubulitis and eosinophils, and is considered when the cause is uncertain or there is no improvement after stopping the drug. **Imaging** Kidney ultrasound to exclude obstruction (kidneys may be normal or enlarged and echogenic); gallium scan is rarely used. ## Differential diagnosis - Acute tubular necrosis (muddy brown casts, ischaemic or toxic insult) - Pre-renal acute kidney injury - Rapidly progressive glomerulonephritis - Acute pyelonephritis - Atheroembolic kidney disease ## Goal of treatment Stop the trigger promptly, support kidney function and reduce inflammation to prevent permanent fibrosis. ## Treatment **Acute** Stopping the suspected drug as soon as possible, or treating the infection, is the key step; the reaction is recorded as an allergy. **Medical** Glucocorticoids are often used when kidney function does not improve within a few days after stopping the drug or the injury is severe, ideally early. **Procedure** Temporary dialysis for severe acute kidney injury, hyperkalaemia, acidosis or fluid overload. **Follow-up** Monitoring and nursing care: creatinine, electrolytes, intake and output, daily weight; avoiding other nephrotoxins and documenting the drug allergy. ## Complications - Acute kidney injury needing dialysis - Chronic kidney disease from interstitial fibrosis - Hyperkalaemia and metabolic acidosis - Recurrence if the drug is restarted ## Prognosis Usually good when the drug is stopped early: most patients recover much of their kidney function within weeks. Longer exposure, delay in diagnosis and fibrosis on biopsy predict incomplete recovery and chronic kidney disease. ## Test yourself Think of the answer, then tap the question to see it. ## What is the most common cause of acute interstitial nephritis? Drugs, especially beta-lactam antibiotics, NSAIDs and proton pump inhibitors. ## What classic triad suggests drug-induced acute interstitial nephritis? Fever, rash and eosinophilia, though it occurs in only a minority of patients. ## What urinary finding is typical of acute interstitial nephritis? Sterile pyuria with white blood cell casts. ## What is the most important first step in managing drug-induced acute interstitial nephritis? Stopping the culprit drug. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/conditions/acute-interstitial-nephritis/) ## Related conditions - [Acute kidney injury](https://durgical.com/en/conditions/acute-kidney-injury/) - [Cutaneous drug reactions and DRESS](https://durgical.com/en/conditions/cutaneous-drug-reactions-and-dress/) - [Sarcoidosis](https://durgical.com/en/conditions/sarcoidosis/) - [Sjögren disease](https://durgical.com/en/conditions/sjogren-disease/) - [Acute pyelonephritis](https://durgical.com/en/conditions/acute-pyelonephritis/) - [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/) - [Hyperkalaemia](https://durgical.com/en/conditions/hyperkalaemia/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Interstitial nephritis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000464.htm) (MedlinePlus (U.S. National Library of Medicine), 2024). [← All conditions](https://durgical.com/en/conditions/) ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/conditions/acute-interstitial-nephritis/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/acute-interstitial-nephritis/