AKI Flashcards
What is the testing algorithm for AKI?
Look for:
Prerenal
Postrenal
Intrarenal
What do all forms of AKI cause?
Azotemia (increased BUN) and increased Creatinine
What are some causes of postrenal azotema?
BPH
prostate cancer
Urethral stricture
Bilateral compression (pelvic cancer, stones)
How do you diagnose Post renal AKI?
Catherization
RENAL U/S
> 100 mL bladder
How do you treat postrenal AKI?
Catherization
Treat underlying cause
What do you see in early obstruction?
Tubules still intact
FENa
What do you see in long standing obstruction
Tubules start to die
Decreased BUN reabsorption
- Decreased sodium reabsorption (FENa >2%)
What causes pre-renal azotemia?
Decreased blood flow
- Dec. GFR, azotemia, oliguria
What are some diseases seen in prerenal?
Volume depletion Low CO CIrrhosis Sepsis Nsaids Cyclosporine ACEIs ARBs
What do you check in prerenal?
Check Orthostatics
- CBC
- BMP
- FENa
- FEUrea if on (diuretics)
How does ANG-II affect kidney blood flow?
Ang-II preferentially vasoconstricts EFFERENT ARTERIOLE
Prostaglandins released due to Inc. sympathetics affect which part of Renal BF?
Causes afferent vasodilation
NSAIDs + Cyclosporins preferentially vasoconstrict which part of renal vasculature?
Afferent arteriole
ACE inh and ARBs vasodilate which part of the renal circulation?
Efferent arteriole (Blocks Ang-II)
What does the RAAS system do?
Increased aldosterone causes increased Na absorption
- Increased urea/NH4 reabsorption
IF the tubules are intact what would be the FENa in dehydrated people?
FENa
What are the BUN:CR of Prerenal?
> 20
What is the FENa of prerenal?
What is the FEUrea of PreRenal?
What is the Urine Osm of Prerenal?
Urine Osm
What will the SG of PreRenal be?
SG >1.020
What is the BUN:Cr of Intra-Renal?
What is the FENa of IntraREnal?
> 2%
What is the FEUrea of intrarenal?
> 55%
What is the Urine Osm of INtra-Renal?
How does contrast cause prerenal aki?
Vasoconstricts plus Toxic
What can cause ATN?
Prolonged Ischemia Contrast Toxins - Drugs: AGs, Vanco, amphotericin, cisplatin - Endogenous: Hbg, myoglobin - Light chain - Crystals
What causes AIN?
Allergic: B-lactams, sulfa, NSAIDs, PPIs
What types of vasculitidies?
PAN Cholesterol emboli Thrombotic (HUS/TTP/DIC) - Preeclampsia, Antiphospholipid syndrome - Malignant HTN - Scleroderma renal crisis
What do you see in AIN and Vasculitis?
Urine Eosinophils (antibiotics and Chol. Emboli)
How do you treat ATN?
Supportive
- Severe: dialysis
Takes 1-2 weeks for ATN to resolve
How do you diagnose ATN?
Injury + Necrosis of tubular
What do you see on Histo?
Cells detached from BM
- Necrotic debris forms casts
- Tubular dilation + flattening of epithelial cells
- UA: Brown granular casts, Heme 4+, NO RBCs: Hbg, Myoglobin
Whats the clinical triad of AIN?
Oliguria, FEVER, Rash (days to weeks after drug)
How do you treat AIN?
Stop Drug
- STEROIDS
What is the Hallmark of AIN?
Eosinophils
What is the UA of AIN?
WBC casts WITHOUT Infection
- Eosinophils (rare)
What do you see in Contrast induced AKI?
Pre-renal AKI + ATN
How to prevent Contrast induced AKI?
Isotonic IV fluids Hold ACEI/ARB/NSAID/Diuretic - N-Acetylcysteine Cr Increase by 25% or 0.5 in 48 hours - Peaks 3-5 days - Resolves 7-10days
What is Immunofluorescence of GoodPastures?
Linear
What is IF of Post Strep GN, Lupus nephritis?
Granular
What is seen in IF negative?
Pauci-immune disease
What is seen in Mesangial IF?
IgA nephropathy
What are 3 causes of Crescentic GN?
GoodPastures
Pauci-immune disease (Wegener, Churg-Strauss, Microscopic polyangitis)
- Immune complex GN
What is the Algorithm for Nephritic Syndrome?
1) Nephritis vs Nephrotic
2) Serum complement
- Low: Immune Complex disease
- - ASO titer, ANA/dsDNA, HepB/C, BCs
- Normal: ANCA + AntiGBM Ab
What presents with subepithelial “humps”?
PSGN, Lupus Nephritis(MCC renal disease in lupus)
What is the IF of Lupus nephritis?
IF: Granular (IgG, IgA, IgM, C3, C1a) “full-house”)
What is the complement of Lupus nephritis?
Low C3+C4
What is associated with membranoproliferative GN?
Hep B/C
Can be nephritis or nephrotic
What is the complement in membranoproliferative GN?
Low C3 in MOST PATIENTS
What are the 3 major features of Churg Straus syndrome?
P-ANCA
- Granulomatous inflammation + Eosinophila + Asthma
What is the presentation of Henoch-Schonlein Purpura?
Arthritis, abdominal pain, Purpuric rashes
- IgA deposits in Dermal Vessels + other locations
What do you see in ALports syndrome?
Isolated Glomerular hematuria
- Sensorineural deafness
- Ocular disturbances
What is the EM of Alport’s Syndrome?
“Basket-weave” pattern
- Thickening + Splitting of glomerular BM