Urinary Lithiasis Flashcards
Approx 75% of all stones contain ___ as major constituent and 60% are composed of ___
Calcium; calcium oxalate
Stone formation depends on 4 factors
1) Matrix 2) Precipitation-crystallization 3) Epitaxy 4) Absence of inhibitors of stone formation
Refers to supersaturation of the urine with specific ions composing the crystal
Precipitation-crystallization
Refers to the aggregation of crystals of different composition but similar lattice structure
Epitaxy
If the calculus is present in these areas, then severe abdominal or flank pain (renal colic) occurs
Pelvis, calyx, ureter
Renal colic typically radiates where
Anteriorly to the scrotum or labia
Nephrocalcinosis is seen most commonly in premature neonates receiving ___ and in children with ___
Furosemide, medullary sponge kidney
Most accurate study to diagnose urolithiasis
Unenhanced spiral CT of the abbdomen and pelvis
T/F Metabolic evaluation should be undertaken in ALL children with urolithiasis
T
MC metabolic abbnormality in children with CaOx and CaPhos calculi
Normocalcemic hypercalciuria
Increases solubility product of calcium oxalate crystallization 7-10x more than calcium
Oxalate
Death from renal failure occurs in untreated patients with hyperoxaluria by age ___
20
Extrarenal deposition of CaOx
Oxalosis
Renal insufficiency + elevated plasma oxalate
Oxalosis
Risk factor for formation of CaOx and CaPhos stones due to low excretion of an important inhibitor of calcium stone formation
Hypocitraturia
Rare autosomal recessive disorder of the EC of the renal tubules that prevents absorption of 4 dibasic amino acids resulting in excessive urinary excretion of these products
Cystinuria
4 dibasic amino acids unabsorbed in cystinuew
Cysteine, ornithine, arginine, lysine
Calculi resulting from UTI caused by urea-splitting organisms
Struvite calculi
Urea-splitting organisms, infection of which causes formation of struvite calculi
Most often Proteus, occasionally Kleb, E.coli, Pseudomonas
Presence of urea-splitting organisms in the urine causes
Urinary alkalinization and excessive production of ammonia –> precipitation of magnesium ammonium phosphate (struvite) and calcium phosphate
Staghorn calculi
Struvite calculi
Shown to facilitate stone passage in adults by decreasing ureteral pressure below stone and decreasing frequency of peristaltic contraction of the obstructed ureter
α-adrenergic blockers (tamsulosin, terazosin, doxazosin
Alkaline therapy may be effective in dissolution of what type of stones
Uric acid, furosemide-associated calculus, cysteine calculi
Effective management strategies for children with hypercalciuria to prevent stone formation
1) Reduction in calcium and sodium intake 2) Thiazide diuretics (reduces renal Ca excretion) 3) K citrate (calcium stone inhibitor)
Effective management strategies for children with uric acid stones
1) Allopurinol 2) Urinary alkalinization >6.5 with NaHCO3 or Na citrate
Effective management strategies for children with cysteine stones
1) Urinary alkalinization 2) D-penicillamine (increases solubility of cysteine)
