Synopsis
Recognise chronic tubular and interstitial kidney injury, distinguish analgesic-associated papillary disease from other causes, and prevent avoidable progression or obstruction.
- Chronic tubulointerstitial nephritis describes tubular atrophy and interstitial fibrosis caused by sustained toxic, metabolic, immune, infective, obstructive or inherited injury.
- Typical clues are slowly declining eGFR, relatively modest albuminuria, a bland or low-grade urinary sediment, concentrating impairment and tubular electrolyte or acid-base abnormalities.
- Review prescribed medicines, over-the-counter analgesics, combination products, supplements, occupational exposures and previous chemotherapy; a standard medication list may miss the cause.
- Analgesic nephropathy classically combines chronic interstitial damage with papillary necrosis after substantial cumulative exposure, historically especially combination analgesics; ordinary occasional paracetamol use is not the same diagnosis.
- NSAIDs can also produce haemodynamic acute kidney injury, acute interstitial nephritis, hyperkalaemia, sodium retention and papillary injury, especially during hypovolaemia or alongside renin-angiotensin system blockers and diuretics.
- Exclude reflux, recurrent pyelonephritis, chronic obstruction, lithium exposure, hypercalcaemia, hypokalaemia, Sjogren syndrome, sarcoidosis, monoclonal disease and environmental toxins when the history suggests them.
- Stopping an offending exposure may stabilise function but established interstitial fibrosis is often irreversible, so standard CKD cardiovascular and kidney-protection measures remain essential.
- Visible haematuria, papillary calcification or filling defects must not be attributed automatically to analgesics because stones, infection, obstruction and urothelial malignancy require consideration.
Key red flags
Flank pain, visible haematuria, sterile pyuria or passage of tissue may indicate papillary necrosis, with sloughed material capable of obstructing the ureter.
Hydronephrosis, recurrent infection, retention symptoms or discrepant kidney size may reveal a structural cause that needs prompt decompression rather than immunosuppression.
Investigation priorities
Confirm chronicity and detect tubular or dangerous metabolic complications.
Management branches
Chronic kidney impairment has a tubular or bland-sediment pattern.
- Reconstruct prescribed and non-prescribed analgesic, lithium, antimicrobial, chemotherapy, supplement and occupational exposures with approximate dose and duration.
- Map creatinine, urine and electrolyte changes against exposure, dehydration, infection and obstruction events rather than relying on the latest result.
- Discuss suspected essential-medicine toxicity with the prescribing specialty and pharmacy before withdrawal or substitution, documenting a safe shared plan.
Key medicines
NSAID withdrawal or avoidanceDo not prescribe a replacement NSAID dose for suspected analgesic nephropathy; review indication and stop or minimise exposure with the responsible clinician.Abruptly removing analgesia without an alternative can cause harm. Create a multimodal pain plan, consider opioid and paracetamol limits, and account for gastrointestinal, cardiovascular and renal risks.
ParacetamolIf appropriate, use the lowest effective licensed dose within the current BNF maximum and reduce or avoid it where liver disease, low body weight or interacting factors require.Check combination products to prevent duplicate dosing. Overdose is an emergency, and prolonged high exposure still needs indication and safety review.