Tubulointerstitial nephropathy and nephrotoxins Flashcards
Acute tubulointerstitial nephritis (ATN) Chronic tubulointerstitial nephritis (CTN) Analgesic nephropathy Aminoglycosides Rhabdomyolysis
How does ATN present? When should you consider it as a diagnosis?
AKI
Consider ATN when there are no obvious pre or post renal causes of AKI
What is seen on biopsy of ATN?
inflammatory cell infiltrate in interstitium +/- tubule
What are the causes of ATN?
- Drugs - abx, NSAIDs, PPIs, diuretics, ranitidine, anticonvulsants, warfarin
- Infection - strep, pneumonia, staph, campylobacter, e.coli, mycoplasma, CMV, EBV, HSV, hep A+C
- Autoimmune: SLE, sarcoid, Sjogrens, ANCA
What is the treatment of ATN?
Stop causative agent or rx underlying cause
Steroids?
What is CTN?
Insidious onset of interstitial nephritis w slowly progressive renal impairment
What is seen on biopsy in CTN?
interstitial fibrosis and tubular atrophy
What are the causes of CTN?
- drugs - NSAIDS, lithium, calcineurin inhibitors, aminosalicylates (sulfasalazine), chemo e.g. cisplatin
- Infection: TB, pyelonephritis, leptospirosis, HIV
- Immune: sarcoid, sjogrens
What is the treatment of CTN?
Stop causative agent
Rx underlying cause
CKD Rx: ACEi/ARB, glucose, lipids
what drugs cause analgesic nephropathy?
NSAIDs
Aspirin
Paracetamol
How does analgesic nephropathy present?
Hx of chronic pain
Silent until CKD
What tests would you do to help diagnose analgesic nephropathy
- Urinalysis - sterile pyuria? proteinuria
- USS - small irregular kidneys
- IVU - cup and spill appearance - clubbed calyces
- Non-contrast CT - reduced renal mass, papillary calcification
- Biopsy - CTN secondary to papillary necrosis
How is analgesic nephropathy treated?
discontinue analgesia
manage CKD
Exclude obstruction from sloughed papilla
What are examples of aminoglycosides?
Gentamycin
Streptomycin
What are RFs for ahminoglycosides causing nephropathy?
high dose
prolonged use
CKD
volume depletion
What is rhabdomyolysis?
Skeletal muscle breakdown leading to release of intracellular contents (K+, myoglobin) into extracellular space
Increased cytokines and lowered nitric oxide leads to renal vasoconstriction
myoglobin is filtered by the kidney and leads to obstruction and inflammation
Explain how rhabdomyolysis leads to kidney damage
- Myoglobin usually binds to haptoglobin but increased amount leads to M exceeding binding capacity, XS M interacts w Tamm-Horsfall proteins and forms casts causing obstruction
- Low BP due to renal vasoconstriction caused by increased cytokines and lowered nitric acid so lack of blood flow to kidney
- Increased uric acid can cause crystals leading to obstruction
How does rhabdomyolysis present?
Hx of trauma, surgery, immobility, hyperthermia, seizures,
Muscle pain, swelling, tenderness, AKI
Red brown urine
How is rhabdomyolysis diagnosed?
Myoglobinuria (false +ve on dipstick but no rbcs on microscopy) raised K+ and PO4, low calcium, increase in plasma creatinine kinase
What is the treatment of rhabdomyolysis
Supportive
Urgent treatment for hyperkalaemia
IV fluid rehydration
Maybe RRT?
Give examples of antimicrobials that are nephrotoxic
aminoglycosides (gentamycin) co-trimoxazole Penicillins Rifampicin Aciclovir Amphotericin
Give examples of anticonvulsants that are nephrotoxic
lamotrigine
valproate
phenytoin
Give examples of anaesthetics that are nephrotoxic
methoxyflurane
enflurane
Give examples of crystals that are nephrotoxic
urate
Give examples of parasites that are nephrotoxic
toxoplasmosis
leishmania
Give examples of other drugs that are nephrotoxic
PPIs furosemide thiazides ACEi/ARBs lithium iron calcineurin inhibitors cisplatin
Give examples of bacteria that are nephrotoxic
Strep legionella TV chlamydia mycoplasma salmonella syphilis campylobacter
Give examples of viruses that are nephrotoxic
EBV CMV HIV measles adenoviruses
Give examples of proteins that are nephrotoxic
Igs in myeloma
Light chain disease
Hb in haemolysis
Myoglobin in rhabdo
