AKI-Path Flashcards
early signs of kindey injury include _____, while later signs include?
increased creatinine, increased BUN, decreased GFR; oliguria and proteinuria
causes of pre-renal acute kidney injury
trauma (septic shock), reduced perfusion, hypoxia
causes of post-renal acute kidney injury
urinary tract obstruction (such as benign prostate hyperplasia)
gross pathology of a “shock” kidney looks?
larger and lighter in color than a normal kidney (no filtration, no urine production)
what blood nourishes the tubules?
from the glomerulus, which filter but do not use up oxygen (thus an injured glomerulus will result in hypoxic tubules)
what are the four categories of intra-renal injury? (by location)
tubular causes, interstitial causes, vascular causes, glomerular causes
what are the two types of tubular injury?
ATN, tubular obstruction
what is the most common cause of acute kidney injury in adults?
ATN
ATN is divided into what two pathogenic categories?
ischemic ATN and nephrogenic ATN
causes of ischemic ATN
hemorrhage, shock, burns, dehydration, diarrhea, heart failure
pathologic findings of ischemic ATN
dilated dysmorphic tubules and flattened or missing epithelial cells (without damage to basement membrane)
why does the outside of the kidney turn white during ischemic ATN?
shunting of blood away from cortex
causes of nephrogenic ATN
drugs (aminoglycosides), organic solvents (ethylene glycol, carbon tetrachloride), and poisons (paraquat)
pathologic findings of nephrogenic ATN
tubule lumen filled with dead, necrotic epithelial cells that have been sloughed off (BM still intact)
is ATN reversible?
YES
tubular obstruction is also known as?
cast nephropathy
causes of tubular obstruction
multiple myeloma, lymphoproliferative disorders
how to detect light chain cast nephropathy
anti-kappa stain
histo of a glomerulus overrun by massive influx of PMNs; can destroy architecture if not treated (fibrosis)
pyelonephritis
gross pathology of pyelonephritis
pus bumps with darker hemorrhagic rim
most common causes of allergic interstitial nephritis
NSAIDs, diuretics, ABX (beta lactams)
histological findinds of allergic interstitial nephritis
lymphocytes and eosinophils in the interstitial space
allergic interstitial nephritis is reversed by?
stopping the drug!
name two major categories of vascular intra-renal injury
emboli (usually cholesterol) and thrombotic microangiopathy (HUS, TTP)
this type of intra-renal injury may occur secondary to emboli or thrombi in small arteries of kidney
ischemic ATN
what occurs in thrombotic microangiopathy
dz of small blood vessels that results in thrombosis of small arteries, thrombocytopenia, and hemolytic anemia (due to fragmentation during passage through vessel)
a blood smear of TMA would show?
schistocytes and lack of platelets
causes of TMA
idiopathic, infection-induced (VTEC, shigella), drug-induced, pregnancy-induced, autoimmune, hereditary
histology of TMA artery
intimal expansion obliterates lumen
what is the most common cause of acute kidney injury in children?
HUS; especially post-diarrheal HUS from VTEC
pathogenesis of HUS
verotoxin injures endothelial cells, leading to narrowed lumen (and decreased blood flow, often with thrombi) and expanded subendothelial zone, which traps platelets and fragments RBCs
triad of HUS
hemolytic anemia, thrombocytopenia, uremia (toxicity due to renal failure)
severe ischemia may result in?
cortical necrosis
signs of glomerular disease
asymptomatic hematuria, nephritic syndrome (blood and proteins in urine), asymptomatic proteinuria, and nephrotic syndrome (protein in urine)
mnemonic for nephritic syndrome
PHAROAH
pathology of glomerulonephritis
PMNs invade glomerulus, RBCs leak from broken basement membrane, resulting in RBCs and RBC casts in urine, proteinuria, and ATN from decreased flow to tubules
causes of severe glomerulonephritis
post-infection (usually group A strep), immune-complex diseases (type 3 hypersensitivity)
pathology of acute postinfectious glomerulonephritis
diffuse enlargement and hypercellularity of glomeruli, infiltration of PMNs and lymphocytes (usually resolves after several weeks)
immunofluorescence of acute post-infectious glomerulonephritis will show?
granular peripheral reactions for IgG and C3 along BM, later only C3
definition of crescentic glomerulonephritis
accumulation of epithelial cells and macrophages in Bowman’s space, resulting in a crescent-shaped structure (usually rapidly progressive)
pathology of crescentic glomerulonephritis
minute ruptures of peripheral BM result in spilling of fibrin into Bowman’s space, which promotes lymphocyte and macrophage infiltration, which eventually strangle the glomerular capillaries
