Nephrolithiasis Flashcards
nephrolithiasis: it is common, ___% of people have some time in their life. Men or women more?
12% have at some time in their life
Men > women
4:1 ratio
what age do most people get kidney stones?
Most often 20-40 years old
risk for kidney stones ______ after the first one.
increases, once you have one its more likely youll get another
what is the most important predisposing factor for kidney stones? what are two following important factors?
More in high humidity and high temperatures (more likely dehydrated)
- FH and genetics
stones: Form in ________ and move_______
Form in proximal tract (near kidney) and move distally
5 types of salts that cause kidney stones. which is the most common?
- Calcium oxalate (most common 80%)
- Calcium phosphate
- Struvite
- Uric acid
- Cystine
will calcium oxalate show up on xray ?
likely YES
what two factors of urine cause stones?
low volume and altered pH
acidic vs basic (alkaline) urine?
Acidic urine, low pH, usually <5.5: Decreases solubility of uric acid
Alkaline urine, high pH : Decreases solubility of calcium phosphate and magnesium ammonium phosphate
which type of stone is from alkaline urine ?
struvite
is urine naturally acidic or basic?
acidic
nephrolithiasis is asymptomatic until ________ or _______
inflammation or obstruction
what is the pain like with kidney stones? (description and location/radiation)
acute and quickly unbearable
- waxes and wanes: “renal colic”
- flank: can radiate to back, groin, legs, suprapubic, or labia
- CVA tenderness
if it is renal colic, where is the stone usually located?
ureter
what are the associated symptoms of kidney stones?
- Nausea and vomiting (but any severe pain can cause this)
- Hematuria, dysuria, urinary frequency
- Fever and chills
kidney stone pts often are static or waking around?
VERY restless, uncomfortable
kidney stones, if an ileus (lack of movement of the intestines) is present, then there might be ________ _______
abdominal distention
why might a CBC be helpful for kidney stone Dx?
WBC may indicate infection, but can also indicate inflammation. iIf negative WBC, could rule out systemic infection presenting as flank pain
what is the most critical Dx for kidney stones?
visualization of the stone
pH of urine: if <5.5 or if >7.5 … what type of stones are you thinking it is?
Urinary pH
pH < 5.5 think of uric acid or cystine stones
pH > 7.5 think struvite stones
what are you checking UA for?
pH, blood, crystals, pyuria (usually) or bacteriuria (maybe)
what are 4 other labs you can do for kidney stones? (besides UA and CBC)
urine culture, CMP, 24hr urine collection, stone analysis (to determine content)
what are three types of imaging for kidney stones? which is the most common?
- CT (most common)
- plain film KUB (kidney, ureters, bladder)
- US
when would US be the best imaging in regards to kidney stones?
looking more for obstruction like blocked and enlarged kidney (hydronephrosis- a must not miss)
*can also use CT for this
what kind of stones could you see on x-ray?
calcium or cystine stones would show up (both radiopaque)
- uric acid stones would NOT be seen (radiolucent)
what is IVP and what do we use now instead of this?
IV pyelogram - inject a die in and take an xray
- use helical CT now
why do we use CT over Xray? who would you not want to use either for?
you can see radiolucent stones
- on Xray you can only see radiopaque ones
- don’t use if pregnant (use US instead)
what is the “test of choice” for flank pain?
helical CT
if someone has a history of stones and now has symptoms of a stone, do you need imaging?
NO
three goals of txt for stones?
- determine if theres an obstruction
- pass or extract stone
- prevent formation of future stones
what is stone expulsive therapy?
alpha blockers or Ca++ channel blockers (usually for 2 wks) to encourage ureteral smooth muscle relaxation
-for immediate decrease in pain and enhanced rate of stone passage (a controversial txt option)
are lots of fluids good for kidney stone pts?
kind of, you give it to them to make them pee and pass the stone but it might increase the pain, better for prevention than txt
what do you do for asymptomatic stones? what if they grow or become symptomatic?
No treatment just monitoring with renal ultrasound
If growing or symptomatic, intervention needed
If urine is obstructed/infected need to do what?
If urine is obstructed/infected need to bypass obstruction or get rid of stone
If infection proximal to an obstructing stone, need what?
admission for abx and drainage
what can you give for pain txt of kidney stones?
pain control:
- narcotics (morphine, meperidine, and butorphanol)
- Toradol
what is the caution with prescribing toradol?
NSAID ADRs and not good for the elderly
stone expulsive therapy: outcomes are clearly in favor if stone is ______
<10 mm
which are the preferred agents to use for stone expulsive therapy?
those that effect BP less (use tamsulosin)
likelihood of passing a stone (without intervention) based on size : <5mm, 5-10mm, >10mm
<5mm: about 80% will pass
5-10mm: about 20% will pass
>10mm: Won’t pass without intervention
stone <5mm: will likely pass ______ within ____ to ____ weeks.
Outpatient, will likely pass spontaneously within 2-4 weeks
txt of stone <5mm (3 parts)
- Oral hydration-drink a lot
- Strain urine to catch and analyze stone
- Oral analgesics- frequently need opioids
Combination NSAID and opioid better than either alone
txt of stone 5-10mm (2 parts)
- Increased fluids and oral analgesics
3. Elective lithotripsy or ureteroscopy
what is a lithotripsy (ESWL)?
Extra corporal shock wave lithotripsy
- uses anesthesia, dissolving stones with ultrasound waves
what is ureteroscopy?
Ureteroscopy- scope through bladder up ureter, visualize stone and laser or grasp with instrument
what are the indications for ureteroscopic stone extraction? (4)
Indication: severe pain, unresponsive to medications, fever, persistent nausea and vomiting
if there is an obstruction (regardless of stone size) what are two txt options?
ureteral stent or percutaneous nephrostomy
what is a ureteral stent?
tube that bypasses stone in ureter
what is percutaneous nephrostomy?
tube into collecting system of kidney to relieve obstruction of urine
three options for txt of stone >10mm
- Extracorporal shock wave lithotripsy if renal stone <2cm or ureteral stone <1cm
- Percutaneous nephrolithotomy (i.e. surgery) for stones > 2cm
- Ureteroscopic fragmentation
what is the most important preventative step for all stone types?
prevention of dehydration (drink 2x water that you normally drink)
___% of stones recur in __ years
50%, 5 years
prevention of Ca oxalate stones (3 parts)
- Water, lemonade (incr. Citrate)
~Double normal intake - Thiazide diuretics (decrease urinary calcium)
- Decrease dietary protein and Na
increase in _____ will decrease Ca-oxalate stones.
Paradoxically, ↑Ca++ will decrease Ca-oxalate stones!
prevention of cystine stones
- Increase fluids
2. alkalinization of the urine with acetazolamide
prevention of uric acid stones
- low protein diet
- allopurinol to decrease levels
- urinary alkalinization
prevention of struvite stones
- antibiotics (what’s the bug?) (proteus)
- acidification of urine
- cranberry juice
2 complications of stones
infection and obstruction
