Stone Formation and Urolithiasis Flashcards
T/F. Stone formation is multifactorial
True (e.g. genetic, diet, physical environment, stress)
T/F. Rate of stone formation is not proportional to % of large crystals and crystal aggregates.
False (proportional)
Determines stone production
Saturation of each salt and the concentrations of inhibitors and promoters
3 anatomic ureteral constrictions
[1] Ureteropelvic junction, [2] crossing of ureter at level of iliac vessels, [3] ureterovesical junction
5 surgical constrictions of the ureter
3 anatomic constrictions + [4] ureter crossing vas deferens/broad ligament, [5] ureteral meatus
T/F. Stone <4 mm can’t pass through GUT
False (readily pass)
T/F. Nephrocalcinosis is a medical emergency
False (do not have potential for obstruction)
Central event in stone formation
Supersaturation
Most important urinary ion
Calcium
Amount of Ca reabsorption
<2 % excreted in urine (the rest is reabsorbed)
T/F. Increase in monosodium urates and a decrease in urinary pH further interfere with Ca complexation and therefore promote crystal aggregation
True
T/F. Ca affects amount of oxalate absorption in small bowel
True
T/F. Uric acid is a product of pyrimidine metabolism
False (purine metabolism)
T/F. Na directly affects Ca stone formation
False (indirectly as it regulates Ca metabolism)
Most active inhibitory component of urine
Citrate
Inhibitor which is a component of struvite calculi
Magnesium
T/F. Sulfate is not a stone formation inhibitor
False
Pathogenesis of calcium stones
↑ urinary calcium
↑ urinary oxalate
↓ level of urinary citrate
Tx for type I absorptive hypercalciuria
Cellulose phosphate
Most common absorptive hypercalciuria
Type II
Tx for Type II absorptive hypercalciuria
Dietary calcium restriction to 400 to 600 mg/day
Tx for type III absorptive hypercalciuria
Orthophosphate
Hypercalciuria 2⁰ to Primary hyperparathyroidism (most commonly due to adenoma)
Resorptive Hypercalciuric Nephrolithiasis
Infection stone 2⁰ to urea splitting organisms e.g. Proteus, Pseudomonas and assoc. with staghorn calculi
Struvite
Composition of struvite
Mg, Ammonium (gives alkaline pH), Phosphate
T/F. Uric acid stone more common in women
False (men)
Struvite vs uric acid stones
Struvite: dissolve in acid just like xanthine
Uric acid: dissolve in alkaline
Tx if serum uric acid is high
Allopurinol
Stone due to inborn error of metabolism i.e. intestinal absorption of dibasic amino acid
Cystine
Signs and symptoms of stone
Pain (renal colic), hematuria, fever, nausea and vomiting
Common nerve pathway of kidney and stomach
Celiac ganglion
Classic signs of appendicitis
Dull pain navel area that progresses to sharp pain in LRQ; loss of appetite; abdominal pain after nausea and vomiting; abdominal swelling; fever; inability to pass gas
Radiation of pain in proximal ureter stone
Radiates to the groin and testicle in male, labia majora and round ligament in female
Simplest, minimally invasive, cheapest imaging
UTZ
Next line imaging if negative in initial imaging
Retrograde pyelography
Series of x-rays (plain KUB)
Scout films
Contraindication for IV pyelography
↑ serum creatinine; dye is nephrotoxic
Uric acid and xanthine stone on pyelography
Radiolucent
Calcium oxalate and calcium phosphate stones on pyelography
Radio opaque
Obliterated psoas line on imaging might mean
Mass in retroperitoneal area
May be performed to delineate the entire ureter to check for stones, masses, or strictures using dynamic fluoroscopy
Retrograde pyelography
Stones on CT
Hyperintense regardless of nature
Benefits of stent
Allows medication to come in contact with stone or else all meds will to the contralateral kidney
Management of obstructed and infected kidney and fever
Emergency drainage
Ureterolithic agents to relax ureter and reduce peristalsis
Hyoscine butylbromide (buscopan) and alpha adrenergic blockers
Agents for acidification of struvite stone
Suby’s G solution and hemiacidrin
Effect of orange juice on urine
Alkalinize
Oral alkalinizing agents
Na or K bicarbonate and K citrate
Pain relievers for colic pain
IM 50-100 mg meperidine or 10-15 mg morphine, NSAIDs
Chance of spontaneous passing of 4-5 mm stone
40-50%
Chance of spontaneous passing of >6 mm stone
<5%
Extracorporeal shock wave lithotripsy effective on
<2 cm stone
Can be used to drain obstructed, infected, dilated kidney if catheters can’t pass through
Nephrostomy tube
Indicated for staghorn calculi and bigger stones
Percutaneous nephrolithotomy
Complication of percutaneous nephrolithotomy
Bleeding
T/F. No need to assess renal function before treating a stone.
False (assess first!)
For proximal ureteral stone, be it retroperitoneal or transperitoneal
Laparoscopy
