Urolithiasis

Question 1

Composition of stones

Answer 1

• calcium oxalate (most common)
• calcium phosphate
• uric acid
• struvite/ triple phosphate
• cystine
• other

Question 2

• most common stone type
• mutiple etiologies, dehydration most common, forms in a wide range pH, radio-opaque, not dissolvable

Answer 2

calcium oxalate

Question 3

• dehydration (MC), hyperuricosuria
• forms in ACIDIC URINE (pH < 6)
• radiolucent
• dissolves with urinary alkalinization

Answer 3

Uric acid

Question 4

etio: Metabolic conditions such a renal tubular acidosis, migraines, medications

• forms in ALKALINE URINE
• Radio-opaque

Answer 4

Calcium phosphate

Question 5

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

Answer 5

Magnesium ammonium phosphate

Question 6

• 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

Answer 6

cystine

Question 7

etio: laxative abuse, UTI radioluscent

Answer 7

ammonium acid urate

Question 8

etio: precipitated drug (ex: indinavir/HIV antivirals)

• radiolucent & NOT visible on non-con CT

Answer 8

protease inhibitor stones

Question 9

etiologies and risk factors for stones

Answer 9

• 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

Question 10

symptoms of stones

Answer 10

• 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

Question 11

obstructive vs non-obstructive stones

Answer 11

• obstructing stones typically cause symptoms secondary to hydronephrosis (celiac ganglion compression)
• non-obstructing stones are usually asymptomatic, incidentally notes
• can have intermittent obstruction–> colic

Question 12

• 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

Answer 12

hydronephrosis

Question 13

Complications of hydronephrosis?

Answer 13

• UTI, pyelonephritis
• urosepsis
• renal atrophy
• renal insufficiency/failure
• urolithiasis
• HTN
• renal rupture–> peritonitis

Question 14

labs to order for stones?

Answer 14

• CBC
• BPM
• UA
• Urine gram stain and C&s
• pregnancy test
• Mg
• PO4
• uric acid
• PTH
• TSH
• 24h urine stone
• calculus analysis

Question 15

treatment of stones?

Answer 15

• fluids, antiemetics, pain control
• surviellance: small non-obstructing renal calculi
• dissolution therapy: uric acid stone–> urinary alkalinization
• medical expulsive therapy
• surgical intervention

Question 16

• 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

Answer 16

Medical expulsive therapy

Question 17

• 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

Answer 17

ESWL (extracorporeal shockwave lithotripsy)

Question 18

complications of ESWL

Answer 18

• hematoma
• skin ecchymosis
• UTI
• Pain
• Steinstrasse (stone street)
• lower stone clearance rate

Question 19

• 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

Answer 19

Ureteroscopy with laser lithotripsy

Question 20

Ureteral stone particularly distal ones

Answer 20

Rigid ureteroscopy

Question 21

• Failed ESWL
• Renal stones < 2cm
• complex anatomy
• proximal ureteral stone

Answer 21

flexible ureteroscopy

Question 22

• 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

Answer 22

Percutaneous nephrolithotomy (PCNL)

Question 23

Large stones > 2.5cm
failed ESWL
complex anatomic cases
staghorn stones

Answer 23

PCNL

Question 24

complications of PCNL?

Answer 24

• infection
• pneumo/hemothorax
• injury
• extravasation of urine
• rare- bowel injury

Question 25

indications of emergent treatment

Answer 25

* 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

Question 26

can be placed with ESWL, URS, PCNL and in the setting of infection, ureteral injury or ureteral surgery

Answer 26

ureteral stents

Question 27

prevention of stones?

Answer 27

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

Question 28

what should you know about first time stone formers?

Answer 28

* 50% recurrence within 5-10 years * recurrent stones can lead to renal impairment, infections, pain, multiple ER visits, surgeries

Question 29

non-medication managment of stones?

Answer 29

* 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

Question 30

medical management of hypercalciuria?

Answer 30

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

Question 31

medical management of hypcitrauria?

Answer 31

Potassium citrate * urinary alkalinizer, increases urinary citrate goal pH > 6/5 * monitor for hyperkalemia (sodium bicarbonate, baking soda)

Question 32

medical management of hyperuricosuria?

Answer 32

Allopurinol * decreases urinary uric acid * works even if normal serum uric acid

Question 33

medical mangement of cytinuria?

Answer 33

Thiola * forms bond with cysteine to increase its urine solubility