Urolithiasis Flashcards
Composition of stones
- calcium oxalate (most common)
- calcium phosphate
- uric acid
- struvite/ triple phosphate
- cystine
- other
- most common stone type
- mutiple etiologies, dehydration most common, forms in a wide range pH, radio-opaque, not dissolvable
calcium oxalate
- dehydration (MC), hyperuricosuria
- forms in ACIDIC URINE (pH < 6)
- radiolucent
- dissolves with urinary alkalinization
Uric acid
etio: Metabolic conditions such a renal tubular acidosis, migraines, medications
- forms in ALKALINE URINE
- Radio-opaque
Calcium phosphate
struvite and triple phosphate
- Etio: UTI (MC)- bacteria produce ammonia that builds up in the urine
- forms in ALKALINE urine
- radio-opaque
- dissolves with urinary acidification
Magnesium ammonium phosphate
- etio: Cystinuria (hereditary genetic disorder)
- typically form stones starting in childhood
- cystine is a derivative of the amino acid cysteine
- forms in ACIDIC urine
- radio-opaque
- dissolves with urinary alkalinization
cystine
etio: laxative abuse, UTI radioluscent
ammonium acid urate
etio: precipitated drug (ex: indinavir/HIV antivirals)
- radiolucent & NOT visible on non-con CT
protease inhibitor stones
etiologies and risk factors for stones
- anatomic- obstruction/stasis
- urine composition- pH, hypercalcicuria, hypocitrauria, hyperoxaluria, hyperuricosuria, hypomagnesiuria
- low urine volume (MC)
- diet: sodium, low fiber, high oxalate, carbonated drinks
- Hypokalemia
- disease states- obesity, DM, HTN, gout, metabolic acidosis etc
- UTI
- sedentary lifestyle
- medications
symptoms of stones
- flank pain: colic/wave-like, sharp/severe (radiation to abdomen, testicles/labia
- secondary to obstruction
- Hematuria: gross or microscopic blood
- GI: N/V
- asymptomatic
- LUTS: urgency/frequency/dysuria/pressue
obstructive vs non-obstructive stones
- obstructing stones typically cause symptoms secondary to hydronephrosis (celiac ganglion compression)
- non-obstructing stones are usually asymptomatic, incidentally notes
- can have intermittent obstruction–> colic
- presence of fluid in the kidneys as a result of obstruction
- obstruction can be anywhere along urinary tract (meatus to kidney)
- can be silent or symptomatic
- obstruction can be from a stone (MC), strictures, BOO, BPH, extraureteral compression (think LAD/malignancy) trauma, edema, congenital anomalies, UPJ, blood clot, reflux
hydronephrosis
Complications of hydronephrosis?
- UTI, pyelonephritis
- urosepsis
- renal atrophy
- renal insufficiency/failure
- urolithiasis
- HTN
- renal rupture–> peritonitis
labs to order for stones?
- CBC
- BPM
- UA
- Urine gram stain and C&s
- pregnancy test
- Mg
- PO4
- uric acid
- PTH
- TSH
- 24h urine stone
- calculus analysis
treatment of stones?
- fluids, antiemetics, pain control
- surviellance: small non-obstructing renal calculi
- dissolution therapy: uric acid stone–> urinary alkalinization
- medical expulsive therapy
- surgical intervention
- trial of spontaneous passage
- hydration, strainer, pain control
- alpha blocker, corticosteroids
- follow up imaging
- appropriate: passable stones, good pain control, no infection, appropriate renal function
Medical expulsive therapy
- historically done in tub bath
- now done with gel pad under lower body & fluoroscopy
- US waves utilized to break up stone +/- stenting
- contraindications- pregnancy, coagulopathy, UTI, renal artery calcifications, AAA, radiolucent stones
- stone favorable parameters: stone size * location, STSD, HUD
ESWL (extracorporeal shockwave lithotripsy)
complications of ESWL
- hematoma
- skin ecchymosis
- UTI
- Pain
- Steinstrasse (stone street)
- lower stone clearance rate
- rigid and flexible
- option for stone basketing
- disadvantage- need for ureteral stent
- good option for failed ESWL or non- ESWL candidate
- cystolitholapaxy
- complications- ureteral perforation, stricture
Ureteroscopy with laser lithotripsy
Ureteral stone particularly distal ones
Rigid ureteroscopy
- Failed ESWL
- Renal stones < 2cm
- complex anatomy
- proximal ureteral stone
flexible ureteroscopy
- removes renal calculi from the kidney through percutaneous access from back into the kidney
- small hole for large stones? larger stones are laser fragmented before removed
- disadvantages: 2-3 day admission, stent and/or nephrostomy tube
Percutaneous nephrolithotomy (PCNL)
Large stones > 2.5cm
failed ESWL
complex anatomic cases
staghorn stones
PCNL
complications of PCNL?
- infection
- pneumo/hemothorax
- injury
- extravasation of urine
- rare- bowel injury
indications of emergent treatment
- Obstructing stone + infection
- bilateral obstruction
- solitary kidney
- refractory pain
- inability to tolerate oral intake d/t NV
- goal is to drain the system: Stent & run, nephrostomy tube
can be placed with ESWL, URS, PCNL and in the setting of infection, ureteral injury or ureteral surgery
ureteral stents
prevention of stones?
complete evaluation
- 24 hour urine for creatinine, Ca, Mg, Citrate, uric acid, oxalate
- serum labs
- dietary assesment
- assess history for risk factors
Dietary managment
medical management
what should you know about first time stone formers?
- 50% recurrence within 5-10 years
- recurrent stones can lead to renal impairment, infections, pain, multiple ER visits, surgeries
non-medication managment of stones?
- avoidance of stone-provoking drugs
- weight loss in the obese
- high fluid intake
- dietary oxalate restriction
- dietary sodium restriction
- limit animal protein excess “fleshy foods”
- low purine diet- uric acid
- avoid extremes of calcium intake
medical management of hypercalciuria?
Thiazide Diuretics
- Decrease urinary calcium & correct acidosis
- increases reabsorption of calcium in the proximal & distal tubules
- inhibits sodium reabsorption in the distal tubule
- monitor for hypokalemia
medical management of hypcitrauria?
Potassium citrate
- urinary alkalinizer, increases urinary citrate goal pH > 6/5
- monitor for hyperkalemia (sodium bicarbonate, baking soda)
medical management of hyperuricosuria?
Allopurinol
- decreases urinary uric acid
- works even if normal serum uric acid
medical mangement of cytinuria?
Thiola
- forms bond with cysteine to increase its urine solubility
