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37 Cards in this Set
- Front
- Back
Can ultrasound detect obstruction?
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no, it can only pick up dilatation of the calices (hydronephrosis)...but if obstruction doesn't dilate the calices, then US can't pick it up
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what are the most common causes of anuria:
- intratubular? - ureter? - urethra? |
intratubular = protein casts, crystals (related to medications)
ureter = stones, tumors, fibrosis urethra = prostate, strictures, blood clots, stones |
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most common cause of UTO in children vs adults
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children = congenital
adults = BPH, stones |
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what are the effects of urinary tract obstruction on renal fxn after 1 hour? after 24 hours?
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after 1 hr = vasodilation, increase RBF, decreased GFR (due to increase pressure of blood, nothing filters), decreased Na absorption, inc tubule pressure
after 24 hours = vasoconstriction, dec RBF and GFR, inc Na absorption (kidney thinks its in shock), stable tubule pressure |
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what's the difference in renal response b/w mild vs complete ureteral obstruction
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unilateral obstruction = initially, vasodilation through prostaglandin, inc bloodflow kidney, maintain GFR; later, inc AG II to constrict efferent arteriole, inc thromboxane A2 to constrict afferent arteriole
complete obstruction = similar to unilateral obstruction events as detailed above early on; at 24 hrs, inflammatory cells will come in and cause vasoconstriction to preserve other critical parts of the body, lose GFR bc you decrease RBF; WHAT'S DIFFERENT IS THAT also will have ANP released that enhances efferent constriction and lessens afferent arteriole constriction BUT BASICALLY, THE REDUCTIONS IN RBF AND GFR 24 HRS ARE THE SAME FOR BOTH UNILATERAL AND BILATERAL URETERAL OBSTRUCTION |
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what is the outstanding clinical feature of complete UTOs?
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anuria!!
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what is the hallmark of UTO on radiography?
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hydronephrosis (use Ultrasound first bc you'd have to use dye for CT that can actually cause obstruction)
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what is post-obstructive diuresis
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polyuria after release of bilateral obstruction (when urea is excreted after relief of UTO, it'll pull water with it as an osmotic agent)
so you'll see hyperkalemia, acidemia, kidney failure, and polyuria (find out why...) |
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tx for unilateral kidney stones
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hydrate, remove it
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tx for ureteral obstruction with kidney failure (like from tumor)
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percutaneous stents
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tx for urethral obstruction
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catherization
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pt just returned from the summer vacation on the beach, with severe flank pain that radiates into the groin. she reports nausea, vomiting and frequent urination.
what's the probable dx? |
possible kidney stone
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what are the most common kinds of stones?
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- calcium-based stones (can be mixed with oxalate or phosphate)
- struvite stones (magnesium ammonium phosphate) - uric acid stones - cystine stones |
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what is the hallmark of UTO on radiography?
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hydronephrosis (use Ultrasound first bc you'd have to use dye for CT that can actually cause obstruction)
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what are the changes in obstruction in terms of early vs. chronic phase
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early (days): tubule dilated, interstitial edema, macrophage infiltrate, adhesion molecules appear/early inflammation
chronic (weeks): HYDRONEPHROSIS, tubule atrophy, chronic interstitial inflammation, intersitital fibrosis |
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which may show polyuria?
a. complete UTO b. partial UTO |
B.
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what are some signs and sx's of urinary obstruction
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H/P: fluctuation of urine flow (anuria = complete UTO)
- pain, if ureteral obstruction - lower urinary sx's: dribbling, frequency, incontinence, nocturia |
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what might you expect to find on the labs of a pt with possible UTO?
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-kidney failure (elevated BUN:creatinine ratio)
-hematuria - hyperkalemia -acidemia -excretion of dilute urine |
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what is the general pathogenesis of kidney stone formation?
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when conc of solute (ie. calcium, oxalate, etc) in urine becomes really high, it will eventually precipitate and become a stones
SUPERSATURATION --> NIDUS --> STONE |
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name 2 protective mechanisms against stone formation despite supersaturated urine with multiple ionic species
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- quick transit time through the tubules
- crystallization inhibitors (like citrates and magnesium ... remember that citrates coat crystals and prevent growth/aggregation, though it does not prevent nucleation) |
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which of these will form in alkaline pH (pick as many as possible):
a. calcium oxalate b. calcium phosphate c. Mg-NH4-phosphate d. uric acid e. cystine |
B, C. remember that phosphate stones will form.
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which type of stones form independently of pH?
a. calcium oxalate b. calcium phosphate c. Mg-NH4-phosphate d. uric acid e. cystine |
A
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which type of stones form in acidic pH urine environment (pick as many as possible)?
a. calcium oxalate b. calcium phosphate c. Mg-NH4-phosphate d. uric acid e. cystine |
D, E
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which type of stone is formed as a result of chronic infection by urea-splitting organisms?
a. calcium oxalate b. calcium phosphate c. Mg-NH4-phosphate d. uric acid e. cystine |
C.
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T or F. high urinary citrate and magnesium allow formation of kidney stones.
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F. they are both inhibitors of kidney stone formation. so the more you have, the less likely you'll have stones
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tx of calcium oxalate stones due to hyperoxaluria?
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supplement dietary calcium, low oxalate diet (less beans, greens, teas, chocolate, vit C), pyridoxine (bc pyridoxine deficiency can lead to hyperoxaluria)
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tx of calcium phosphate stones due to idiopathic hypercalciuria
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hypercalciuria = potassium citrate (inhibitor of stone formation within urine), thiazide diuretic (lower urinary calcium excretion)
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what are three reasons for calcium phosphate stones due to idiopathic hypercalciuria
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-idiopathic hyperabsorption from GI tract (normal vit D levels, low PTH)
-fasting can cause release of Ca from bone, leaving PTH levels normal - abnormal renal absorption of calcium or phosphate |
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name 3 causes of calcium phosphate stones due to secondary hypercalciuria
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- conditions that elevate serum Ca (sarcoidosis, TB)
- endocrine (hyperPTH, hyperthyroidism, cushing's syndrome) - medications (diuretics, vit D, tums) |
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would you give calcium as a supplement to a patient with calcium oxalate stones due to hyperoxaluria? why or why not?
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yes, it will decrease the GI absorption of oxalate
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which of the following does NOT lead to struvite stones (magnesium ammonium phosphate)?
a. haemophilus b. yersinia c. E. coli d. proteus |
C.
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which type of kidney stones are radiolucent (show up on x-ray as dark)?
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uric acid stones
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you suspect your pt has uric acid stones so you want to do a IVP. what is the disadvantage of doing so?
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requires IV contrast, which is nephrotoxic
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young pt comes in with a family hx of "mad stones"... you order a urine microscopy exam that shows up with hexagonal crystals. what do you suspect?
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cystinuria (cystine kidney stones taht are due to high urinary cysteine)
- large genetic componenet |
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tx for cystinuria
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potassium citrate
low Na diet |
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which of the following disorders underlying kidney stones would you give thiazide diuretic for?
a. idiopathic hypercalciuria b. hypocitraturia c. hyperuricosuria d. cystinuria |
a.
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T or F:
- you want to give Ca to a patient with stones - you want to avoid high sodium diet in a patient with stones - you want to give everyone with stones potassium citrate - you want to protect kidney stone pts who ahve stones with vit C |
T, T, T, F
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