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What causes more deaths and disabilities than any other illness in the world?
Ischemic Heart Disease (IHD)
What type of acute renal failure results from injury to nephrons and renal tissue?
What would cause (etiology) Pre-Renal acute renal failure?
- inadequate cardiac output (CHF)
- renal vasoconstriction
- **anything that causes a significant decrease in renal blood flow
Which type of acute renal failure is reversible?
Is intrarenal failure reversible?
maybe, but not rapidly
What are the causes of intrarenal acute failure?
- vascular disease (malignant hypertension, disseminated intravascular coagulation)
- acute glomerulonephritis (SLE, graft rejection, Goodpastures, post Streptoc, autoimmune)
- interstitial disease (drug allergy)
- acute tubular necrosis (ATN) ****MOST common cause
What is the most common cause of intrarenal acute renal failure?
Acute tubular necrosis (ATN): post ischemic and nephrotoxic
What are the 3 types of ARF?
- intrarenal (intrinsic)
- post-renal (rare)
What would you see in the urine if there is glomerular injury/damage?
- dysmorphic RBCs
What are the 2 main causes of glomerulonephritis?
What type of cells have a role in the progression of glomerulonephritis?
Which is a better measure of GFR, BUN or serum creatinine?
What is azotemia?
an excess of urea or other nitrogenous bodies in the blood
What is oliguria?
scant production of urine in relation to fluid intake
What does a specific gravity test that is high tell us?
- urine is concentrated
- patient could be dehydrated
What does a specific gravity test that is low tell us?
the kidney is not concentrating the urine
When are people most at risk for ATN (acute tubular necrosis)?
- post surgery (40-50%)
- obstetric complications
- severe burns
- hypotension +/- hypovolemia, followed by reperfusion injury
What type of antibiotics could cause intrarenal ARF nephrotoxicity?
aminoglycosides (gentamicin, tobramycin)
What are some contributing factors to intrarenal ARF nephrotoxicity?
- Type 1 or 2 DM
- concurrent renal insufficiency
What type of injury is more "patchy" within the nephron?
What type of injury is caused by certain drugs accumulating in the cortex and is usually concentrated in one specific area of the nephron?
What are some causes of intrarenal ARF nephrotoxicity?
- radiographic contrast media
- heavy metals
- heme pigments (bilirubin, myoglobin)
- bacterial toxins
- other factors: age, dehydration, diabetes, renal insuff
What are the typical normal levels of BUN?
What is the normal range of SCr?
Which is easier to test, BUN or SCr?
BUN b/c it is a blood test and SCr is a GFR timed urine test
What are the four clinical stages of ATN?
What does the course of ARF depend on?
- magnitude of the insult
- length of time that hemodynamics are altered
What is the most critical stage of ATN?
What is the normal level of urine output per day?
How much urine is produced in 24 hours in anuria?
less than 50 ml in 24 hours
What will happen to a patient that has ARF fro 2-3 days?
they will become anemic
What can oliguria cause?
- fatal cardiac dysrhthmias
- metabolic acidosis
What are the 2 possible complications of diuresis?
How long does the recovery period of ATN take?
What is the most common cause of death in ARF patients?
infection as toxins render WBCs dysfunctional
What are the causes of chronic renal failure?
- immunologic (SLE)
- infectious (pyelonephritis)
- obstructive (neoplasms)
- metabolic (diabetes)
- vascular (hypertension, infarction)
- nephrotoxins (heavy metals, solvents)
- congenital (renal hypoplasia)
- physical (radiation)
When do we establish chronic renal failure?
when ARF becomes irreversible
what are the most important functions of the kidney?
- water balance (via ADH/vasopressin)
- electrolyte balance (via aldosterone)
- acid-base balance
- secretion of waste products (urea, creatinine)
- blood pressure regulation (RAA system)
- Vitamin D activation (via PTH)
- responds to ANP
Where does renal disease rank on the list of US mortality?
In relation to acid-base balance, what ion does the kidney excrete and what does it reabsorb?
- secretes H+
- reabsorbs HCO3-
What are the 3 main (broad) functions of the kidney?
What 2 substances could you give to test GFR?
What endogenous substance helps us measure GFR?
What is AKI?
acute kidney injury: sudden decline in kidney fxn and azotemia
What is renal insufficiency?
- typically renal fxn is 25% of normal
- GFR is 25-30 ml/min
What do we call a significant loss of renal fxn?
What do we call it when we have less than 10% of renal fxn?
end stage renal failure (ESRF)
increased serum urea and/or creatinine = ?
What is uremia?
azotemia + signs and symptoms: fatigue, anorexia, N/V, pruritis, neuro disorders due to toxic waste buildup, electrolyte disorders, deficiencies
What would we have to do to measure the TRUE GFR, but seldom do?
What are the units for GFR?
What does GFR reflect?
the # of mls of blood filtered by the glomeruli in 1 minute
What is typically measured in mg/dl?
What is typically measured in mls/min and is a rate?
What are two other tests that are used to estimate GFR?
- FeNA: fraction of excreted sodium (reflects kidney's ablility to reabsorb sodium)
- MDRD: calculates estimated GFR
What does MDRD stand for?
modification of diet in renal disease
Will there be more or less creatinine in the blood with a decrease in kidney function?
What is the Cockcroft-Gault Formula for males?
- CCR = (140-age) x weight(kg)
- 72 x SCR
What is the Cockcroft-Gault Formula for females?
- CCR = (140-age) x weight(kg) x 0.85
- 72 x SCR
Who tends to have slightly higher Scr levels, males or females?
males: aroung 1.3 mg/dl
What is GFR useful for monitoring, chronic or acute renal disease?
What is creatinine?
- metabolite of muscle
- produced at a constant rate
What will trauma or muscle breakdown do to Scr?
If creatinine clearance goes up, is that a good thing or a bad thing?
If serum creatinine goes up, is that a good thing or a bad thing?
What is the normal range for creatinine clearance?
If there is an increase in GFR, is that good or bad?
If there is a decrease in GFR, is that good or bad?
What is the cutoff for high IBW when calculating creatinine clearance (what % increase do we have to adjust the equations?)
T/f: both weight in kg and IBW can be used in the Cockcroft-Gault formula.
What is BUN a reflection of?
GFR and urine concentrating capacity
Between Creatinine clearance and BUN, which one tends to overestimate GFR and which one tends to underestimate GFR?
- BUN: under (b/c of reabsorption)
- CCr: over
What is the normal BUN: creatinine ratio?
What are some conditions that increase BUN?
- dehydration: allows increased reabsorption of urea
- slowed flow of urea being reabsorbed= more reabsorption
- Catabolism: GI bleed, cell lysis, steroid use
- Increased protein in diet
- Decreased renal perfusion: CHF, renal artery stenosis)
What are some conditions that decrease BUN?
- good or hyperhydration: decreased urea reabsorption
- liver disease
- SIADH (inappropriate ADH secretion)
Why does creatinine clearance overestimate GFR?
b/c a small amount is secreted by the renal tubules, which increases w/ decreasing GFR
During severe renal failure, what can end up degrading creatinine?
What is another term for BUN?
Why does BUN(urea clearance) under-estimate GFR?
b/c although it is freely filtered by the glomerulus, 30-70% is reabsorbed in the nephron
What are 3 tests that are done for a full urinalysis?
- Urine pH
- Specific gravity
- urine sediment
If a specific gravits is too high, what does that mean?
- urine is too concentrated
- patient is dehydrated
If a specific gravity is too low, what does that mean?
kidney can't concentrate the urine
What is found in a urine sediment?
- RBC (hematuria)
- WBCs (pyuria)
- crystals (as urine cools, these form)
- casts (RBC, WBC, or epithelial tubular)
What is the RIFLE criteria?
Which two stages of RIFLE don't have any urine output?
What is the GFR criteria for the Risk stage of RIFLE?
increased creatinine x 1.5 OR decreased GFR >25%
What is the GFR criteria for the Injury stage of RIFLE?
increased creatinine x 2 OR decreased GFR > 50%
What is the GFR criteria for the Failure stage of RIFLE?
increased creatinine x 3 OR decreased GFR >75%
What is the GFR criteria for the Loss stage of RIFLE?
persistent ARF= complete loss of kidney fxn for > than 4 weeks
What is the GFR criteria for the ESKD stage of RIFLE?
end stage for > than 3 months
What is the most common cause of acute renal failure?
pre-renal (any condition that significantly decreases renal blood flow)
What causes post-renal ARF?
- anything that obstructs urinary excretion
- kidney stones
- prostatic hyperplasia
- neoplasms (tumors)
Can albumin be filtered by the glomerulus?
no, not unless there is injury
What are the 3 main results of glomerular damage?
- damage to the filter = leakage
- damage causing swelling= less filtration
- damage causing scarring = less filtration = buildup of metabolites
What antibody do we see deposited in the kidney and skin of a patient with SLE/lupus (Which Ig?)
What will the RBCs in the urine of a renal transplant patient look like?
dysmorphic and abnormal
Where in the kidney do the aminoglycoside antibiotics tend to accumulate?
What is a cause of oliguria?
acute tubular necrosis (and back leak)
When does the oliguric stage begin and how long can it last?
starts within 1 day and last up to 3 weeks
What happens to the renal blood flow and GFR during the oliguric stage of ATN?
- blood flow = 1/3 of normal
- GFR = 1% of normal
What are the 3 proposed mechanisms of oliguria during ATN?
- back leakage
- tubular destruction
- altered renal blood flow
What is the main complication causing post-renal kidney injury?
In the oliguric stage of ATN, what is the cause of potential anemia?
- suppressed EPO production
- RBC life expectancy is reduced due to hemolysis in azotemic blood
Hyperkalemia and metabolic acidosis during oliguria of ATN are caused by an inability to excrete what two ions?
- K+ : hyperkalemia
- H+ : met. acidosis
Does in increase (up to 6 liters) that occurs during diuresis indicate a renal function returning to normal?
Who are the 3 high-risk patients of acute renal failure?
- trauma patients
- post-op patients
What stage of ARF has the highest mortality rate? (pre-renal, post-renal, or intrarenal)
What are some clinical manifestations of ADVANCED chronic renal failure?
- hypernatremia (due to decr. GFR)
- Hyperkalemia (from oliguria)
- Metabolic acidosis
- magnesium imbalance (can cause cardiac arrest)
- Calcium imbalance = hypocalcemia
- purpura and epistaxis (due to incr. nitrogen waste which causes a decr. in plateley fxn)
What 3 things should we do treat the hypocalcemia associated with advanced chronic renal failure?
- increase calcium intake
- decrease dietary phosphate
- supplement large amounts of vitamin D
____ is directly related to the # of functional nephrons remaining during chronic renal failure, and often the nephrons hypertrophy to carry a bigger load?
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