E Med exam 2 - urinary stones

what are urinary stones made of

small crystalline deposits made of salts, minerals, proteins that are usually in urine.

RF for urinary stones

obesity, lo urine vol, excess dietary meat (purine), excess dietary sodium, insulin resistance, metabolic syn, fhx, gout, bowel surgery/IBD, primary hyperparathyroidism, prolonged immobilization, meds

how does obesity cause kidney stones

promotes hypercalciuria

how does lo urine vol lead to kidney stones

allows solute to supersaturate

how does hi dietary meat (purine) lead to kidney stones

creates acidic urinary environment, depletes citrate (inhibitor), promotes hyperuricosuria

how does hi dietary sodium lead to kidney stones

inc hypercalciuria

how does insulin resistance, met syn lead to kidney stones

ammonia mishandling, changes urine pH

how does fhx lead to kidney stones

genetic predisposition

how does bowel surgery/IBD lead to kidney stones

promotes lo urine vol, acidic urine depletes available citrate, hyperoxaluria

how does primary hyperparathyroidism lead to kidney stones

creates persistent hypercalciuria

how does prolonged immobilization lead to kidney stones

bone turnover creates hypercalciuria

what meds cause kidney stones

indinavir, ephedrine, loop diuretics, topiramate, acyclovir, triamterene

pathophys of kidney stone formation

begins with a nidus that evolves in presence of stone forming substances. saturation of urine with stone forming substances enhances the aggregation fo crystals around nidus.

where do stones typically grow

on papillae or in renal tubules, calyces, or renal pelvis

how does inc sodium in diet contribute to the pathophys of creating renal stones

inc calcium, monosodium urate, and calcium phosphate conc in urine while dec citrate levels

too much protein intake can do what for the pathophys of creating renal stones

inc urinary calcium, oxalate, and uric acid while dec citrate

complete ureteral obstruction by a stone causes an accumulation of urine and dilated ureter called

hydroureter

is GFR inc or dec in complete ureteral obstruction

dec

injury to the kidney from ischemia/hypoxia causes renal tubules to

lose ability to conserve sodium, secrete potassium, and acidify or concentrate urine

how is Cr affected by kidney stones

no rise in Cr bc unobstructed kidney functions at a greater rate

RF for urinary stones

highly dependent on saturated urine (dec GFR and dec urine vol), areas of hi humidity and temp (dehydrated and dec urine vol), diet (inc sodium, oxalates, purine, not enough citrates), met acidosis (prolonged fasting), genetic factors (cystinuria=AR d/o where cystine is excreted in excess)

most kidney stones are

calcium stones

what causes calcium stones to form

hyeprcalciuria. hi urine Ca conc.

what dz cause hypercalciuria

hyeprparathyroid dz, diet

pathophys of calcium stones

inc fat in digestive tract combines with calcium, rapidly absorbing calcium. modest inc in oxalate absorption causes stones to form. hi ca diet predisposes to inc ca excretion.

how do calcium stones appear on XR

radiopaque

food high in oxalate

beans, beets, beer, black tea. chococlate, coffee, nuts. soy milk, spinach, soda, tofu, rhubarb

struvite stones are m/c seen in what pop

women with recurrent UTIs

what pathogens cause struvite stones to form

protease or pseudomonas

large stone that takes up more than oe branch of the collecting system in the kidney

staghorn calculi

how do urinary stones show on XR

radiopaque

what condition causes uric acid stones to form

hyperuricosuria in gout

pH in uric acid stones

<5.5

how do uric acid stones show on XR

radiolucent

how do cystine stones form

abnl high excretion of amino acid, cystine being the only AA that is insoluble in urine.

how do cystine stones appear on XR

radiolucent

what should you ask a pt regarding their hx that has kidney stones

assess RF for stone development, prior stone related outcome, hx of renal dz, important mimickers.

RF for poor outcome with stones

renal function at risk, hx of difficulty with stones, and infxn

in pts with renal stones you should exclude

abdominal aortic aneurysm and renal artery infarction

what dz is freq mistakened for renal stones

AAA

how to distinguish between if a pt has renal stones or an AAA

stones don’t usually show in pts over 60 w/o prior hx of kidney stones and do not cz HoTN

why does renal artery thrombosis mimic stone sx

swelling of infarcted kidney and is assoc with hematuria

if pt is pregnant and presents with kidney stone sx what should be in ddx

ectopic preg

presence of stones above the ureter usually present as

asx

when is hallmark colicky pain produced in kidney stones

when stone travels down the ureter

when a pt has severe non remitting pain as rhythmic contractions what does that indicate about the state of the stone

attempt to advance the stone

how does kidney stone pain present

sudden localized flank pain w n/v. pt is constantly moving, pain radiates anteriorly over abdomen and into groin. pt has microscopic hematuria

when a kidney stone pt has urinary urgency what does that mean for the state of the stone

stone is advancing to the ureterovesical junction

stones in the upper ureter have pain where

flank

stones in the mid-ureter have pain where

radiate to the lower anterior quadrant of the abdomen

a distal ureter stone has pain where

groin

stones at the ureterovesical junction can mimic

UTI by causing freq, urgency, and dysuria

what do you look for when evaluating a pt to see if they have kidney stones

look for signs of infxn, dysfxn, and possibility of pregnancy. test all females of childbearing age for pregnancy when considering renal colic to help direct imaging and exclude ectopic pregnancy

what test is ordered to r/o infxn

UA

if infxn is found on UA what is indicated

get urine culture and sensitivities to guide abx therapy

what imaging is best for dx stones

abd XR and renal US

first line tool for dx kidney stones

CT abd/pelvis

when you retrieve a stone what do you do

stone analysis to identify its components

what are you looking for on 24 hr urine collection

vol, pH, calcium, uric acid, oxalate, phosphate, citrate

what type of CT imaging is indicated for kidney stones

non contrast CT. obtained from top of kidney to bladder base

secondary signs of ureteral obstruction that can be seen on CT to better make a determination of kidney stones

ureteral dilatation, stranding of perinephric fat, dilatation of collecting system, renal enlargement

first line imaging in pregnant pts

US

what is a limitation of US

can see big stones but not stones under 5mm

US can be good in dx ureteral stones where in the ureter

proximal and distal ureters

US is BAD for dx stones where

in mid-ureter

when do we do an abd XR

when we can see and locate the stone on a CT scan then we order XR to find a radiopaque stone

stones <5mm prognosis

pass spontaneously with fluids and analgesia

med that can facilitate stone passage by dilating the ureter

alpha 1 adrenergic blockers (tamsulosin, terazosin, doxazosin)

does forced IVF facilitate pain control or stone passage

no, doesn’t make a difference. only give if pt has deficit from vomiting or limited oral intake

how do NSAIDs help with kidney stone tx

directly acts on ureter bc inhibits prostaglandin synthesis.

what NSAID to tx kidney stone

ketorolac

why are opioids given for kidney stone tx

pain control. bc causes vomiting NEED antiemetics

what opioid for tx kidney stone

morphine

pt has ureteral stone, fever, renal insufficiency, systemic signs of infxn. how to tx

IV abx

first dose abx to tx kidney stone infxn

piperacillin-tazo, cefepime, cipro

if stones don’t pass after a trial period what tx is indicated

ureteroscopic stone extraction (USE) or extracorporeal shock wave lithotripsy (ESWL)

how does USE tx kidney stone

small endoscope put thru the urethra and bladder into the ureter. stone is extracted or fragmented then extracted

how does ESWL tx kidney stone

visualize stone with fluoroscopy or US and target high freq sound waves to cause fragmentation. place stent for easier passage. most fragments pas sin 2 wks. don’t tx women w this method

how to tx pt with stones in kidney who have no obstruction or infxn signs

no tx

how to tx stones >2cm

ESWL + stent

how to tx stone in inferior calyx of kidney and has sx

percutaneous nephrolithotomy (PCNL)

how to preform a PCNL

1 cm incision in flank, PCN needle gets passed into pelvis of kidney. confirm needle placement via fluoroscopy. guide wire passed thru needle into pelvis. needle taken out and guide wire still remains. then nephroscope can pass thru and take out small stones. if stone is too big then is crushed using US probes then fragments are removed

how to prevent kidney stones

double your original fluid intake, restrict Na and Ca, bran binds w Ca and inc intestinal transit time. avoid large amounts of purine/oxalates. potassium citrate supplements inc urinary pH. allopurinol of uric acid stone forming patients

if a stone is 1cm can it pass on its own

no

what type of pts can pass larger stones

pts with a pmhx of a ureteral dilation from previous stone passage

stones that are not removed can eventually become

hydroureter, hydronephrosis, and irreversible loss of kidney fxn

an infected stone can cause

pyelonephritis and septic shock if not properly tx

who gets discharged from the hospital

pts with smaller stones, w/o infxn, and when pain is controlled by oral analgesics. give pt urinary strainer and tell them to save any stones and give to pathology

how long does it take for stones 5-6mm to pass on their own

7-30 days

if pt develops fever, vom, or uncontrolled pain what is indicated

return to hospital

if a urologist is going to do surgical therapy or lithotripsy on a pt what should they be informed of before procedure

if pt is on anticoagulants/anti PLT

absolute indications for admission

intractable pain or vomiting, urosepsis, single or transplanted kidney w obstruction, AKI, hypercalcemic crisis, severe medical comorbidities/adv age

relative indications for admission

fever, solitary kidney or transplanted kidney w/o obstruction, obstructing stone w signs of urinary infxn, urinary extravasation, significant medical comorbidities, stone unlikely to pass = large stone above the pelvic brim