Exam 3: Renal AKI Flashcards
What is the very general definition of AKI
AKI:
An abrupt decline in renal function as measured in rise in BUN:creatinine ratio OR drop in urine output
KDIGO Definitions of AKI:
1. Increase in serum creatinine by ____ in 48 hours
OR
- Increase in serum creatinine to ____ times baseline, known or presumed to have occured in prior 7 days
OR
- Urine volume _____ for 6 hours
KDIGO Definitions of AKI:
- Increase in serum creatinine by > 0.3 mg/dL within 48 hours
- Increase in serum creatinine to >1.5 times baseline (presumed to have occured in past 7 days)
- Urine volume < 0.5 mL/kg/hr for 6 hours
CKD is defined as kidney damage or GFR of ______ for three months or more irrespective of cause
GFR is defined as kidney damage or GFR < 60 for three months or more irrespective of cause
AKI:
Etiologies can be
1.
2.
3.
AKI:
Etiologies can be Pre - renal, intrarenal, or post renal
Pre-Renal Causes of AKI:
Absolute decrease in effective circulatory volume:
Relative decrease in effective circulatory volume:
Impaired renal autoregulation with low ECV:
Renal Vasoconstriction or Occlusion
PreRenal Causes of AKI
Absolute decrease in ECV: hemmorhage or volume depletion
Relative decrease in EVC: heart failure, cirrhosis
Impaired renal autoregulation with low ECV: NSAIDS, ACEI/ARBs
Renal vasoconstriction or occlusion: renal artery stenosis, hypercalcemia
Urine in Pre-renal State of AKI:
Since kidneys per se are fine with intact tubules, ____ is retained in an attempt to conserve volume
Urine is ____ with _____
Urine in pre-renal state of AKI:
Kidneys are per se fine, Na/H20 will be retained to conserve volume
Urine is bland with no WBCs or RBCs
Urine Indices in Pre-Renal State of AKI:
Urine will be _______ in an effort to conserve volume and sodium as much as possible
What happens to serum bun/cr ratio?
Urine Indices in Pre-Renal State of AKI:
Urine will be concentrated in an effort to conserve volume and sodium as much as possible (>500)
Urea gets reabsorbed with sodium and water, so BUN:creatinine ratio is HIGHER (20:1)
Acute Tubular Necrosis:
What is it?
Explain the different causes
Then give examples of what will cause each category
Acute Tubular Necrosis:;
Injury to renal tubules leading to AKI
Most common cause of AKI in hospitalized patients
ATN can be due to toxic causes or ischemia
Toxic:
- exogenous (antibiotics like vancomyocin, antifungals like amphotericin, chemo agents, contrast, mannitol)
- endogenous: myoglobin (rhabdo), uric acid, hemoglobin, bilirubin (liver failure)
Ischemia:
- prolonged prerenal state
Acute Tubular Necrosis:
______ and _____ are highly suceptible to ischemic injury
________ are susceptible to toxic injury
Acute Tubular Necrosis (ATN):
Proximal convoluted tubule and thick ascending limb are prone to ischemia
Proximal tubules are most susceptible to toxic injury
Tubular segments that have high o2 requirement from high metabolic rate are thought to be most suceptible to injury
Acute tubular necrosis: Clinical Course:
Initiation Phase (hours to days): _____ tubular injury, potentially reversible if diagnosed early
Maintanence Phase: (1-3 weeks)
- may be prolonged to 3 months
- ______ renal injury
- generally _____uric during this phase
- ______ urine with ____
Recovery Phase:
- repair and regeneration of tubules
- recovery of renal function with decreasing BUN and creatinine
- ____uric phase and at risk for ____ K and ___ Na due to impaired reabsorption
Urine Analysis in Intrinsic Kidney Injury
Urine is ______
Urine Na is ______
Serum BUN/Cr is _____
What does this reflect?
Urine Analysis in Intrinsic Kidney Injury
Urine is abnormal (kidneys screaming for your attention)
Urine Na is high… > 40 (tubules are injured, impaired reabsorption of sodium)
Serum BUN/Cr ratio is low (<10:1)
This reflects impaired tubular function
Urinary Casts:
They are _____ in shape
They are aggregations of _______
Urinary casts are formed under what conditions?
Thus urinary casts are indicative of ___ GFR?
Urinary Casts:
They are cylindrical
These are aggregations of glycoproteins
Urinary casts are formed under LOW flow, acidic conditions
Urinary casts are indicative of low GFR (can also be seen in glomerular diseases)
Rhabdomyolysis:
Common cause of AKI in _____
Breakdown of _____
Urine characteristics?
Rhabdomyolysis:
Common cause of AKI in males (athletes, those training in HIIT or crush injury)
Breakdown of muscle tissue (aka myo..lysis)
Urine characteristics: reddish brown urine due to myoblobin
Rhabdomyolysis causing renal failure:
Rupture of skeletal muscle causes contents to be released into blood stream
Cause of renal failure is typically ____ forming a ___
Causing ______ GFR due to clogging the ____
Rhabdomyolysis causing renal failure:
Rupture of skeletal muscle causes contents to be released into blood stream
Cause of renal failure is typically myoglibin forming a proteinaceous gel…. causing decreased GFR
That myoglobin gell gets clogged in the loop of Henle (u-bend in kitchen sink)
“Bloody Urine in Rhabdomyolisis:
What is the reddish brown color in rhabdo caused by?
Rhabdomyolysis
Brown-reddish urine is due to MYOGLOBIN
Post Renal/ Obstructive Uropathy:
Structural or functional hindrance to urinary flow leading to ____ and ____
Can be ___ or ____ obstruction
Post Renal/Obstructive Uropathy:
Structural or Functional Hindrance to urinary flow leading to back up of urine and decrease in GFR
Can be upper urinary tract obstruction (ureters) or lower urinary tract obstruction (bladder and below)
Upper Urinary Tract Obstruction (ureters involved):
Renal failure seen in _____ or _______
Common causes?
How to dianose?
Upper Urinary Tract Obstruction (ureters involved):
Renal failure seen in bilateral obstruction or single functioning kidney or unilateral obstruction with baseline CKD
Common cause: bilateral kidney stones, extrinsic compression by tumors/fibrosis
Diagnosis: Ultrasound or CT (hydronephrosis, aka watery urine back up into kidney)
Lower Urinary tract obstruction:
Common causes?
Clinical findings?
Diagnosis?
Lower Urinary Tract Obstruction:
Common causes: BPH, drugs, neurogenic bladder
Clinical Findings: fullness of bladder on palpation
Diagnosis: post void residual, or ultrasound with distended bladder
