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28 Cards in this Set
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stones precipitate when |
urine concentration of stone components is too high
solid objectsi nurine can act as nuclei to start crystallization |
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what are the stone types |
Calcium* Ca Oxalate** Ca Phosphate mix of Ca types
uric acid struvite cystine |
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what are risk factors for stone risk? |
too water (inadequate intake or too much loss) nuclei for cystallization
or specifically too much stone component not enough inhibitor |
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what plaque does Ca phosphate concretion in renal tubule make? what happens |
Randall's plaque
it erodes through urothelium. then stone deposits on the exposed plaque (goes from tubule into pelvis) |
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so risk factors for Ca Oxalate stones specifically |
hypercalciuria: can be urine only (filtered out fast enough: GI absorption, high vit D activity, renal leak of Ca out, met acidosis) or secondary to hypercalcemia
hyperoxaluria: excess absorption from GI**, vit C-> ox in alkaline urine, primary hyperoxaluria: AR, enzyme defect
not enough inhibitor: citrate for Ca, Mg for oxalate
hyperuricemia: CaOx stones form on uric acid crystals |
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how does oxalate absorption in GI become too high? |
idiopathic
excess ingestion of high-oxalate foods
low levels of oxalobacter bacteria which degrades oxalates
low binding of oxalate in gut, so more is free to be absorbed (Ca usually does this, so more Ca means less Ox absorbed. Mg can also do this. So Ca Ox stone pts should not lower Ca intake**) |
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what are some high oxalate food? |
dark tea dark beer chocolate nuts dark leaf dark berries |
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why would there be enteric hyperoxaluria |
ox binds to Ca and Mg in colon normally and is eliminated.
But in fat malabsorption, fatty acids bind Ca and Mg (celiac, GI resection, cystic fibrosis, Crohn's disease) |
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So pt has stone. Lab says >20% Ca Phos.
What is differential? |
hyperparathyroidism: bone resorption -> HCO3 and phosphate, and then excess Ca HCO3 and Phos excreted in urine. Urine will have high pH, Ca, phos. |
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What is uric acid a metabolite of?
Why are uric acid crystals common?
What is the obvious tx?
Why don't other animals have this problem? |
Adenosine and guanosine -> xanthine --xanthine oxidase-> uric acid
Uric acid isn't very soluble.
Block xanthine oxidase
They have uricase which uric acid -> allantoin which is soluble |
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what are the biggest risk factors for getting uric acid stones? |
excess uric acid production
pH too low****** at low pH, there is a lot of free uric acid (pKa 5.4) so it precipitates out. At pH 6.5 >90% of uric acid is soluble |
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what factors would lead to excess uric acid levels? |
high red meat intake
idiopathic gout myeloproliferative disorder chemotherapy (dead cells -> purines to metabolize) genetic metabolic disorders: hypoxan-guan transferase deficiency; glycogen storage dz |
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struvite
what pH favors it? so what else is sometimes in the stones?
how bacteria can cause these? what does this form? |
Mg NH4 PO4
not soluble at high pH so Ca-P sometimes in stone
proteus: has urease enzyme so urea -> ammonium (part of stone and raises pH which pulls out PO4). So that with the normal Mg -> struvite = staghorn stone since grows and fills collecting system |
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which bacteria are urea splitters? |
Proteus mirabilis*** other Proteus too
klebsiella
pseudomonas
rare species of e. coli |
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so what are the risk factors for struvite stones? |
UTI's with urea-splitters, so any UTI risk factors (female, catheter) |
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what's the difference between cysteine and cystine? |
cysteine is the aa
cystine is two cysteine's that are linked by covalent bond between their S's |
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so how do people get cystine stones? |
AR defect in GI and kidney tubule so tubular reabsroption is imparied so cystine levels become high and stones form
worse in homozygotes than heterozygotes
can also form staghorns |
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how do you keep from making cystine stones? |
keep cystine in solution by diluting with lots of water to have nocturia at least once per night
thiol groups replace a cysteine in cystine and are more soluble: 6-mercaptoproprionyl glycine, D-penicillamine, captopril |
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what diet recommendations could you give in general to prevent stones? |
drink more water drink more citric juices (Ca stones inhibitor)
eat less animal protein (ups Ca absorb in GI and has purines -> uric acid)
decrease Na intake: kidneys reabsorb more Na and so more Ca too |
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acute severe pain in flank, can move lower over time or can radiate to labium/testis/glans intermittent, in waves nausea/vomit CVA tenderness pt moves to try to relieve pain |
renal colic = kidney stone |
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severe pain nausea/vomit tenderness in abdomen guarding or rebound tenderness hurts to move |
peritonitis |
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how do you do imaging in a renal colic case? |
non-contrast CT "stone protocol" unless pregnant, had too many CT's already
alternatives then: US MRI |
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if pt has stone, what is the thing you can't miss?
how do you check this? |
if there is also a UTI
the obstruction and infection can be a life-threatening emergency so missing it can be fatal:
judge based on urinalysis (tx if nitrities or leukocyte esterase or microscope: WBC or bacteria) and clinical scenario. not enough time for culture. |
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again. When checking for infection in colic pt: if the UA is negative, what would make you suspect infection? |
fever systemic inflammation unusually severe pain perinephric stranding on CT (inflammation sign) |
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what do you give pt with renal colic for rx? |
NSAID- a potent one. Might have to IV since vomiting.
Opiod- IV for faster since these hurt so bad
anti-emetic if they need it |
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what tx do you use to help someone pass the stone "medical expulsive therapy"? like medicine, not surgery or stone laser |
α-blocker which relaxes smooth muscle which ureteral spasm will block the stone
tamsulosin has less HTN risk, more literature terazosin or whatever is cheapter but cross rxn with sulfa allergy
any of these drugs raises chance of passing stone to 79% instead of 50% |
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what treatment will you do for stones if
infection is suspected intractable pain solitary kidney or bilateral obstruction |
immediate stent/percutaneous nephrostomy |
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what treatment will you do for stones if pain stone increasing in size recurrent UTI's with same organism lower kidney function due to stone |
elect to do definitive stone treatment |
