Nephrolithiasis Flashcards
Kidney Stones
- what are they
- most commonly formed due to….
- types of stones
what is it
- solid mass of crystals (hence painful) which form in the kidney and pass through the GU tract (variation in size)
most common cause in inadequate hydration and love urine volume
types
- calcium oxalate stones MC
- calcium phosphate
- uric acid stone
- struvite (infection)
- cystine
reasons for calcium oxalate stones
calcium + oxalate in the stone = MOST COMMON type
- urine contains high amounts of oxalate AND calcium
- due to eating foods with high amoutns of oxalate (black tea, beets, chocolate, nuts, potatoes and spinach)
- conditions can increased calcium in the urine: hyerparathyroidiam, renal hyercalcemia, immobilization syndrome
reasons for calcium phosphate stones
(aka why might the urine be alkalyzed)
calcium phosphate stones: often occur with oxalate stones
- result due to : alkaline urine due to renal function
normal urine: between 6.0-7.5 (4.5-8.0) alkaline 8.0+
alkaline urine beacause of…
- lots of fruit and veggies
- antiacids and diuretics
- kideny disease or UTI
- dehydrated (concentrated urine = higher pH)
- pregnancy
reasons for struvite stones (magnesium, ammonium phosphate)
most commonly in women –> due to UTI!!! think infection when you see struvite
- these form as a result of bacteria causing UTIs –> proteus, pseudomonas, klebsiella, staph aureus
- fast growing: occupt entire kideny: staghorn caculi concern for urosepsis aka sepsis which arises from urinary causes
Uric Acid Stone formation
uric ACID: aka acidic conditions of the urine
- more common in men
- associated with chronic dehydration
- increased risk in those with gout
- cheomtherapy
- diets high in animal protein
- acidic urine pH <5
Cystine Stones
- due to a genetic condition called cystinuria
- failure of the renal tubes to reabsorb cystine which then accumulates in the urine
where can kidney stones obstrurt (within the GU tract)
- renal pelvis: where the kidney attaches to the ureter (think struvite here)
- UPJ: ureteropelvis junction: where the ureter first narrows coming out of the renal pelvis
- Pelvic Brim: where the ureter crosses the illiac vessel it narrows
- UVJ: ureterovesical junction: where the ureter meets the bladder most common site
Risk Factors for a kidney stone
Urinary Composition
what types of compositions
high urine calcium: elevted calcium in urine (50% more)
higher urine oxalate
low urine citrate: citrate helps PROTECT against stone formation (low levels = higher risk, higher levels = protective)
high urine uric acid: for uric acid stone formation risk
low urine volume: dehydration increased stone lieklihood
acidic urine: favors uric acid stones
alkaline urine: favors calcium phosphate stone formation
Risk factors for a kidney stone
Dietary considerations
(minerals)
Fluid Intake: low intake = low output = increased risk (increasing fluid intake can reduce secondary stone formation)
type of fluid matters: sugary drinks increase risk, caffeine reduces risk
Calcium: higher dietary intake = higher urine amount
oxalate: higher dietary intake = higher urine amount (think veggies, fruits, nuts, grains)
potassium: increased potassium decreases stone formation
sodium: excess sodium –> increases calcium excretion –> increased calcium in urine –> increase stone risk
Risk Factors
Dietary Factors
protein: increase animal protein increases calcium excretion & inc. risk (also increases high uric acic, low citrate)
phytate: increase phytate is protective against stones
sucrose: increased surcrose –> increase stone risk
Vit C: increase –> increase calcium oxalate formation and stones
hx. of calcium oxalate reduce vit C to daily RDA
DASH diet & mediterranean diet: helpful to reduce risk of stones
Risk Factors
medications
Calcium Stone
- acetazolamide
- ascorbic acid
- antiacids
Uric Acic Stone
- HCTZ
Xanthine Stone
- allopurinol
non-modifiable risk factors for stone formation
- family history for stones
- genetic predisposition: cystine stone disease
- medical conditions
- hyperparathyroidism (hypercalcemia)
- gout (hyperuricosuria)
- UTI
- IBD
- DM
- obesity
- cystinuria - environmental factors (inadequate fluid intake)
what mostly mimics kidney stones
AAA do not miss get good hx. to differentiate but they will present the same
etopic pregnancy
Signs & symptoms of a kidney stone
-
PAINNNN : acute, severe, intermittent spasm(colicky) pain
- primarily flank pain, abdominal pain which can radiate to the groin
- inability to find a comfortable position - systemtic symptoms
- nausea/vomiting
- sweating
- fever/chills if there is an infection too - Tachypnea, tachycardia
- CVA tenderness
Labs for kidney stones
urinalysis
- hematuria
- + nitrate, leukocytes = get cx. for infection
- crystals
- pH ( alkaline –> think struvite or calcium phosphate, acidic think uric acid)
CBC
- leukycytes for pain/infection
- scr: fr kideny function
pregnancy test!!!
Imaging for kidney stones
- done normally to rule out other causes
spiral/non contrast CT : first-line for suspected stone
- can be used to dx. hydronephritis or other issues
- can be used to rule in/out AAA
other possible imaging
abdominal US: readily avalible but less sensitive for < 5mm
- sensitive for hydronephrosis
- use in pregnancy, contrast dye allergy
- good for gyn. pain
KUB (x-ray)
- 90% of stones wont show up on x-ray
- but those with known stone disease – good to tract them
- good for calcium or struvite
intravenous pyelography
- good for hydronephritis
- must assess kidney function, hydration
- good idea of kideny function and degree of obstruction
- need to use contrast media
Hydronephrosis & kideny stones
what is it
patho
hydronephorisis = backup of fluid into the kidney caused by the stone blockage
management of urolithiasis ACUTE
analgesia
- #1: NSAIDS for pain -ketorolac IV
- narcotics
Antibiotics
- IV antibiotics imipenem + vancomycin
Hydration
- isotonic saline (helps to compensate for the diuresis after lost obstruction)
Antiemetics for N/V
who need to be admitted?
- stone obstruction + UTI, fever urosepsis
- uncontrolled pain/nauseas
- obsturcting stone in the only functioning kdiney they have
- bilateral kidney stones
- obstruction + rising creatitine (shows kideny problem)
- size and location made need surgery
Outpatienet managemnet of stone
meds
stone passing
1: NSAIDS (ketoralac, ibuprofen)
must be able to tolerate oral meds and fluids
(opioids if needed)
antiemetics for vomiting (ondansetron, promethazine)
Infection treatment (no risk of urosepsis)
- ciprofloxicin
- levofloxicin
- cefpodoxime
Stone passing
- stones < 5 mm and distal can pass on their own
- stones > 5mm and < 10mm need MET treatment with alpha 1 blocker: tamsulosin to help stone pass
- confirmation of stone passing: after 4 weeks of met and no evidence –> urology
how does stone size change treatment guidance
- < 4 mm
- < 5
- > 5
< 4 mm: the stone will pass withint 2 weeks
< 5 mm: the stone could pass within 2 weeks (less likely than if smaller)
5 or > 5 mm: refer to urology
refer when…
stone > 5 mm
stone hasnt passed in two/four weeks
how does stone location change guidelines for treatment
renal
ureteral
renal stones
- asymptomatic normally
- if staghorn –> < 2 cm : get lithotripsy to break it up
- > 2 cm : get percutanesous nephrolithotmy
ureteral stones
- < 1 cm : lithotripsy
- > 1 cm: percutaneous nephrolithotomy
follow-up treatment for stones
analyze diet and fluids
analyze medications and risk
- thiazides can help
- potassium citrate can help
annual 24hr. urine
blood tests
F/U imaging
