Le 16 Nephrolithiasis Flashcards
What should you think if recurrent stones?
probably some sort of biochem abnormality
What is the breakdown of prevalence of the 4 types of stones?
80% Calcium
15% Struvite
5% Uric acid
1% cystine
What does presence of cystine stones tell you?
patient has cystinuria?
What is cystinuria?
congenital enzyme deficiency impairing epithelial transport di-basic AA cystine, ornithine, lysine, arginine [COLA]
Transport of what 4 AA is impaired in cystinuria?
- cysteine
- ornithine
- lysine
- arginine
[COLA]
What is the inheritance of cystinuria?
autosomal recessive
What is clinical manifestation of cystinuria?
precipitation of hexagonal cystine stones; present as kids
How do you diagnose cystinuria?
positive Na-nitroprusside test
What is treatment for cystine stones?
alkalinize urine and hydration
What is the appearance/pH of cystine stones?
- radiopaque
- hexagonal
- precipitate at low pH
What is the morphology of struvite stones?
- radiopaque
- coffin lid
- precipitate at low pH
- composed of ammonium magnesium phosphate
What do struvite stones tell you?
indicate urinary tract infection with urease + bugs –> proteus mirabilis, staph, or klebsiella that hydrolyze urea to NH3 and alkalinize urine
What type of stones can form staghorn calculi?
struvite stones
What 3 bugs should you think if struvite stones?
- proteus mirabilis
- staph
- klebsiella
What is treatment for struvite stone?
eradicate underlying infection and surgically remove stone
What are 3 risk factors for uric acid stones?
- decreased urine volume
- arid climates
- acidic pH of urine
Are uric acid stones visible on CT? XRay? ultrasound?
on CT and ultrasound but not xray
What diseases are associated with uric acid stones?
- hyperuricemia [gout]
- diseases w/ increased cell turnover like leukemia
What is morphology of uric acid stones? pH?
- acidic pH
- rhomboid or rosette appearance
What is treatment for uric acid stones?
alkalinization of urine
correct hyperuricosuria by diet or meds [allopurinol]
What are some mechs that cause Ca stones?
- hypercalciuria
- hyperuricosuria
- hyperoxaluria
- hypocitraturia
What is most common kidney stone presentation?
Ca oxalate stone in pt with hypercalciuria and normocalcemia
What are some things that can result in oxalate crystal formation?
- ethylene glycol [antifreeze]
- vit C abuse
- crohns disease
What is hypercalciuria?
urinary excretion > 200 mg/day women > 250 mg/day men