10.30: Renal IV Flashcards
What are the 3 types of AKI?
“Acute Kidney injury”
- **AKA: “ATI” “ATN”
1. Ischemic
2. Toxic
3. Combined - **Often stated as: Usually referred to AKI due to ATI
Presentation of ATI?
“Acute tubular injury “
- Rapid reduction in renal function
- Uremia
- Fluid overload
- Electrolyte abnormalities
- Acidosis
- Oliguria
- Increased creatinine
- ***50% may not show oliguria
Pathogenesis of ATI?
- Tubular injury with disturbance in blood flow
- Reduced GFR, vasoconstriction, low nutrient delivery
- Toxic from waste products and lack of O2
- Necrosis, exfoliation, and regeneration of cells
Difference between ischemic and toxic ATI?
Ischemic: Patchy areas of damage along tubule
Toxic: Diffuse damage along tubule
***Both begin in proximal tubules with necrotic cells detaching and damaging / obstructing later parts of tubules
Classic presentation of ATI?
- Younger person in accident w/ loss of blood
- Drop in BP and urine output
- Increase creatinine
What is common during recovery from ATI?
- Ptn. accumulated excessive fluid and waste
- Will need to undergo weeks of dialysis
- Marked polyuria as renal function returns to normal
Common causes for ischemic ATI?
- Trauma
- Sepsis
- Pancreatitis
Common causes of toxic ATI?
- Antibiotics
- Contrast dyes
- Poisons
- Organic solvents: Mercury, antifreeze
Common presentation of combined ATI?
- Trauma causing large release of myoglobin in blood and urine: toxic to tubules
- Oliguria with dark brown urine
- Dipstick positive for RBC: is actually myoglobin
- Microscopic negative for RBC
- Increase in BUN
Why is polyuria seen in recovery phase of ATI?
- GFR increase more rapidly than tubule epithelium recovers
- Thus tubules cannot fully resorb leading to polyuria
- Once cells recover, urine output is normal
3 categories of tubulointerstitial nephritis?
- Infectious: acute or chronic pyelonephritis
- Drug related
- Other: Metabolic or neoplastic
Difference between primary and secondary tubulointerstitial nephritis?
Primary: only renal tubules and epithelium
Secondary: Often associated with autoimmune or glomerulonephritis as well
2 types of infectious tubulointerstitial nephritis?
- BACTEREMIC: circulating bacteria settles in kidney causing nephritis
- ASCENDING: infection in lower tract (bladder / urethra) with obstruction or other reason for retention allowing urine to flow backwards to kidney = nephritis
Main cause of urinary reflex leading to ascending movement?
- Ureter does not fully close during voiding allowing for backwards flow of urine
- Common cause of htn. in children
Signs of acute pyelonephritis?
- Sudden onset
- Costovertebral pain
- Fever / malaise
- Increase frequency and urgency
* **Chronic is more insidious
What is acute inflammation with PMNs in tubules and interstitium characteristic of?
Acute pyelonephritis
Dispersion of blood between medulla and cortex?
Cortex: 90%
Medulla: 10%
***When there is ischemia the papillary tip of medulla is first to go
Predisposing factors of papillary necrosis?
- Analgesics
- Sickle Cell
- Diabetes
- Obstruction
- TB
Who is interstitial nephritis common in?
- Immunosuppressed patients: transplantees
- Mimics rejection of kidneys
Characteristics of chronic pyelonephritis?
- Slow, scarring onset
- Gradual insufficiency with nocturia / polyuria
- Dilated tubules
- Obliterated glomeruli
What is xanthogranulomatous pyelonephritis?
- Mimicks tumor, caused by proteus
- Large stones lead to obstruction and scarring
Presentation of drug induced interstitial nephritis?
- 25% rash
- Renal failure: more prevalent in elderly
- Blood and eosinophils in urine
Cause of drug induced interstitial nephritis?
- IgE T cell mediated response to:
1. NSAIDS
2. Diuretics
3. Antibiotics
How to treat drug induced interstitial nephritis?
- Withdrawal of drug
Typical presentation of drug induced interstitial nephritis?
- Fever
- Rash
- Eosinophils in urine
- Recent diuretic, NSAID, antibiotic administered
- **Not dosage dependent
What are fever rash and eosinophils in urine characteristic of in a ptn. who recently began to take new drug?
Drug induced interstitial nephritis
What is pathology of NSAID induced interstitial nephritis?
- NSAIDs inhibit prostaglandin formation
- Demonstrates podocyte effacement seen in MCD
- Renal failure with increased serum creatinine
Difference and similarity between MCD and NSAID interstitial nephritis?
BOTH: show podocyte effacement
NSAIDs: show increased serum creatinine
What is chinese herb nephropathy?
- Caused by aristolochic acid
- Rapidly progressing interstitial fibrosis and failure
- Seen in chinese women using herbs for slimming
- Increased urothelial carcinoma
When is acute uric acid nephropathy seen?
- Ptn. with leukemia or lymphoma on chemotherapy
- Massive degradation of tumor nuclei leads to release of toxic uric acid
- Mainly tubular in acute, chronic is interstitial
When is chronic oxalate nephropathy seen?
- Bariatric surgery
- Crohn’s disease
- Leads to interstitial nephritis
What is multiple myeloma?
- Plasma cell malignancy
- Light chain IG from plasma cell precipitate in distal tubules
- Can lead to renal failure
- Uric acid and hypercalcemia seen as well
When are subepithelial deposits seen?
Post infectious state
When is increased creatinine seen?
ATI
What does benign htn cause?
- Hyaline arteriolosclerosis
- Narrows lumen
Difference between benign and malignant htn.?
Benign: leads to hyaline arteriolosclerosis
Malignant: Fibrinoid necrosis and hyperplasia of smooth muscle leading to “onion skin” appearance
Common cause of renal artery stenosis?
- Post vascular surgery dislodging clot
What is thrombotic microangiopathy?
- Endothelial injury from many microthrombi in arterioles
- Microangiopathic hemolytic anemia
- Thrombocytopenia from platelet consumption
What can cause thrombotic microangiopathy?
- HUS
- TTP
- Drugs
- Malignant htn.
Presentation of thrombotic microangiopathy?
- Microangiopathic hemolytic anemia
- Thrombocytopenia
- Renal failure
- Diarrhea in kids
- Often caused by E Coli shiga toxin
What is HUS often associated with?
- Child eating hamburger and getting E Coli
- Leads to HUS and diarrhea
