Acute Renal Failure SIM Flashcards
What are some tip-offs that a renal failure is acute and not chronic?
- normal creatinine 1 month ago
- few risk factors for CKD
- normal hematocrit
- abscence of renal cortical thinning on CT
- timing of symptoms (timing of oliguria)
What causes a prerenal issue?
reduced blood flow to the kidneys
What causes a post-renal issue?
obstruciton of urine outflow
What should be on the differential once you’ve decided it’s intrinsic renal disease?
glomerulonephritis
interstitial nephritis
tubular disease
vascular disease
What is interstitial nephritis characterized by?
inflammation and scarring of the tubules and interstitial spaces with relative sparing of the glomeruli and vasculature
What are the three categories of interstitial nephritis?
immune-mediated
infection-mediated
idiopathic
What are the general causes of immune-mediated interstitial nephritis?
drug hypersensitivity
glomerulonephritis from lupus or IgA nephropathy
sarcoidosis, sjogren’s transplant rejection
What are some infection-mediated causes of interstitial nephritis?
pyelonephritis
post-infectious with streptococci, staphylococci, diptheria, legionella, yersinia, leptospira, mycobacterium, mycoplasma, rickettsia, syphilis, toxoplasmosi and tons of viruses
also granulomatous disease - TB and sarcoid
What are three general classes of drugs associated with hypersensitivity interstitial nephritis?
antibiotics
diuretics
NSAIDS
What antibiotics are often associated with interstitial nephritis?
penicillins cephalosporins sulfonamides fluoroquinolones rifampin trimethoprim
What diuretics are associated with interstitial nephritis?
furosemide
thiazides
What symptoms of our patient’s pointed towards NSAID hypersensitivity interstitial nephritis? What are other characteristics of NSAID-induced interstitial nephritis?
recent addition of ibu pruritis - skin hypersensitivity eosinophilia (40%) hematuria (40%) pyuria proteinuria renal failure nephrotic syndrome
Why do you get hyponatremia?
NSAID-induced. I think you can’t get reabsorbtion?
Why is NSAID inhibition of prostaglandin synthesis important here?
prostaglandins are important in water balance because they antagonize ADH, thus inhibiting chloride transport by the thick ascending limb of henle and regulating medullary blood flow.
What is the likely mechanism of drug-induced interstitial nephritis?
likely a CD4+ T cell mediated reactivity or CD8+ cytotoxic T cell-mediated tubular damage
Probably reactive to an antigen on the drug or a drug metabolite
