Interstital Nephritides and Nephrotoxins Flashcards
What is Acute Interstitial / Tubulointerstitial Nephritis
Immune-mediated hypersensitivity ̄c either drugs or other Ag acting as haptans
Causes of Acute Interstitial / Tubulointerstitial Nephritis
Drug hypersensitivity in 70% NSAIDs Abx: Cephs, penicillins, rifampicin, sulphonamide Diuretics: frusemide, thiazides Allopurinol Cimetidine
Infections in 15%
Staphs, streps
Immune disorders
SLE, Sjogren’s
Presentation of interstitial nephritides
Fever, arthralgia, rashes
AKI → olig/anuria
Uveitis
Investigations
↑IgE, eosinophilia
Dip: haematuria, proteinuria, sterile pyuria
Treatment
Stop offending drug
Prednisolone
Chronic TIN
Fibrosis and tubular loss
Commonly caused by:
Reflux and chronic pyelonephritis DM
SCD or trait
What is Analgesic nephropathy
Prolonged heavy ingestion of compound analgesics
Often a Hx of chronic pain: headaches, muscle pain
Features of analgesic nephropathy
Sterile pyuria ± mild proteinuria
Slowly progressive CRF
Sloughed papilla can → obstruction and renal colic
Investigations and treatment of chronic TIN
Ix: CT w/o contrast (papillary calcifications) Rx: stop analgesics
Acute rate crystal nephropathy - cause and treatment
AKI due to urate precipitation
Usually after chemo-induced cell lysis
Rx: hydration, urinary alkalinisation
What is Nephrocalcinosis and its causes
Diffuse renal parenchymal calcification Progressive renal impairment Causes Malignancy ↑PTH Myeloma Sarcoidosis Vit D intoxification RTA
What do nephrotoxins do
Either directly toxic → ATN
Or cause hypersensitivity → TIN
Exogenous nephrotoxins
NSAIDs Antimicrobials: AVASTA Aminoglycosides Vancomycin Aciclovir Sulphonamides Tetracycline Amphotericin ACEi Immunosuppressants Ciclosporin Tacrolimus Contrast media Anaesthetics: enflurane
Endogenous nephrotoxins
Haemoglobin, myoglobin
Urate
Ig: e.g. light chains in myeloma
Pathogenesis of Rhabdomyolysis
Skeletal muscle breakdown → release of: K+, PO4, urate
Myoglobin, CK
↑K and AKI
Causes of Rhabdomyolysis
Ischaemia: embolism, surgery
Trauma: immobilisation, crush, burns, seizures,
compartment syndrome
Toxins: statins, fibrates, ecstasy, neuroleptics
Clinical features
Muscle pain, swelling
Red/brown urine
AKI occurs 10-12h later
Investigations of Rhabdomyolysis
Dipstick: +ve Hb, -ve RBCs
Blood: ↑CK, ↑K, ↑PO4, ↑urate
Treatment of rhabdomyolysis
Rx hyperkalaemia IV rehydration: 300ml/h CVP monitoring if oliguric IV NaHCO3 may be used to alkalinize urine and stabilise a less toxic form of myoglobin.
