Acute Kidney Disease Flashcards
timeline for kidney disease
AKI- hours to days
AKD- less than 3 months
CKD- over 3 months
echo findings w/ CKD
small echogenic kidneys
3 types of AKD
- pre renal: reduced renal perfusion
- intrarenal: vascular, glomerular, tubular, interstitial injury
- post renal: obstructed kidney
causes of pre renal pathology (2 broad causes)
low renal perfusion:
- low ECF volume from GI loss, hemorrhage, diuretics
- altered renal blood flow: sepsis, HF, cirrhosis, hypercalcemia, meds, vascular disease
3 broad categories of intra renal
vascular
(renal parenchymal):
tubulointerstitial- AIN, ATN, tubular obstruction
glomerular disease
causes of ATN (acute tubular necrosis)
decreased renal perfusion (prolonged pre renal) causes ischemic tubular injury
nephrotoxins cause tubular injury
- meds like aminoglycosides
- heme pigments like w/ rhabdo
- iodinated contrast from CT scans
3 phases of ATN
- inititating- hours to day, inciting event until injury occurs
- maintenance- 1-3 weeks, marked decrease in GFR and risk of electrolyte imbalance
- recovery- repair of renal tissue, BUN and Cr back to normal
possible post renal causes
obstruction: large prostate, kidney stone, tumor
increased pressure transmitted to nephrons- must effect both kidneys to have marked GFR reduction
how to exclude post renal
foley cath (would have improvement if post renal), renal ultrasound
3 types of abnormal urine sediment, w/ DDx
- RBC, RBC casts, proteinuria: GN, vasculitis, thrombotic microangiopathy
- WBC, WBC casts, eos: pyelonephritis, interstitial nephritis
- RTE cells, pigmented casts (granular muddy brown): ATN
meaning of hyaline cast
pre renal causes, can be in normal kidney (no cellular filtration)
FENa equation
(UNa x Scr/ Ucr x SNa) x 100
interpret FENA
less than 1%= likely pre renal, Na avid state
over 2%= likely ATN
fractional excretion of urea equation
(Uurea x Scr/ Ucr x BUN) x100
interpret FEurea
less than 35% likely pre renal
over 50 likely ATN- loss of urea reabsorption
effect of NSAIDs on GFR/kidney fn
inhibit intra renal prostaglandins- block afferent dilation and cause reduction in GFR (pre renal)
what to think w/ AKI following cardiac cath
radiocontrast induced ATN nephropathy
less common is atheroembolic disease- can also present w/ livedo reticularis rash, eosinophilia, low C3
course of action with drug induced AIN
remove offending drug, steroids can speed recovery
define renal papillary necrosis
necrosis and sloughing of papillae from lack of blood flow
causes/ tx of renal papillary necrosis
associated w/ NSAIDs, DM, SCD
