SFP: acute kidney injury Flashcards
What are some signs that kidneys aren’t working?
Low urine output, proteinuria, high creatinine
What is the gold standard for measuring kidney function?
GFR
What can AKI lead to?
Chronic kidney disease or end stage kidney disease
To be AKI, one of what 3 factors are needed?
- Increased serum creatinine by 50% within 7 days
- Increased serum creatinine by 0.3 in 2 days
- Oliguria
What volume is considered oliguria?
Less than 400-500
What are some causes of pre-renal AKI?
Hypovolemia, impaired CO, decreased vascular resistance, altered pre-renal hemodynamics from medications or electrolyte imbalance
What are some clinical signs of pre-renal AKI?
Hypotension, tachycardia, fever, dry mucous membranes, decreased skin turgor, oliguria
What are lab findings of pre-renal AKI?
Increased hematocrit, low urine sodium and chloride, high urine osmolality, BUN to creatinine ratio greater than 20:1
What are some things in the kidney itself that may cause pre-renal AKI?
Afferent arteriole constriction, efferent arteriole dilation
What are some intrinsic causes of AKI?
Glomerular injury, vascular injury, microvascular injury
What are common manifestations of intrinsic AKI?
Acute tubular injury and acute interstitial nephritis
What are causes of acute tubular injury?
Low renal perfusion or low oncotic pressures; Ischemia, inflammation, low oncotic pressure, osmotic nephrosis
What are lab findings of acute tubular injury?
BUN to creatinine ratio less than 20:1, urine sodium and chloride elevated, granular/muddy brown urine casts, iso-osmotic urine
How does function in acute tubular injury change with intravascular volume resuscitation?
It doesn’t! it’s an issue with the kidney itself, not a supply issue
Describe how contrast can impact the kidney.
Can cause kidney injury, especially if it is arterial contrast use!
Who is at risk for contrast associated nephropathy?
People with decreased renal function; CKD or AKI
In contrast associated nephropathy, when do we see creatinine peak?
48-72 hours after exposure
How do we prevent contrast associated nephropathy?
Volume expansion with fluids and by halting diuretics
Describe acute interstitial nephritis.
Immune-mediated kidney injury that acts as an allergic reaction; subacute creatinine rise, rash, fever, eosinophilia
What can cause acute interstitial nephritis?
Drugs, infection, systemic disease
What meds are associated with acute interstitial nephritis?
PPIs, fluoroquinolones, NSAIDs, furosemide
What do we see histologically in acute interstitial injury?
White blood cell casts, eosinophils, diffuse interstitial infiltrate
What is the gold standard for acute interstitial injury diagnosis?
Kidney injury
How do we treat acute interstitial injury?
Stopping the underlying cause and possibly steroids
What is rhabdomyolysis?
A pigment nephropathy that is an intrinsic cause of AKI
What are some causes of rhabdomyolysis?
Crush injury, seizures, alcohol/cocaine abuse, drugs
What are lab findings of rhabdomyolysis?
Serum CK higher than 10,000, heme on dipstick but no RBCs in sediment
What is hemolysis in terms of AKI?
Pigment nephropathy that is an intrinsic cause of AKI
What is uric acid nephropathy?
Uric acid crystals in the renal tubules clog up the kidney; it is a tubulointerstitial cause of AKI
How do patients present with uric acid nephropathy?
Severe hyperuricemia and oligoanuric AKI
What is associated with uric acid nephropathy?
Tumor lysis syndrome; acute gout nephropathy is also possible
What are some microvascular injuries associated with AKI?
Vasculitis and thrombotic microangiopathy
What does glomerulonephritis present with?
Hematuria, proteinuria, HTN, edema
What are vascular injuries associated with AKI?
Renal infarct, aortic aneurysm or dissection, renal artery stenosis, atheroembolic disease
What are some post-renal causes of AKI?
Stones, large prostate, retroperitoneal or pelvic mass, foley catheter obstruction, fibrosis
What are the indications for dialysis?
- A- refractory acidosis
- E- electrolytes (hyperkalemia)
- I- ingestion of toxins or metformin
- O- volume overload
- U- uremic symptoms
