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Flashcards in Nephrolithiasis Deck (20):
1

SS - what is it and how to improve?

supersaturation: ratio of salt conc in urine to solubilities
SS>1 crystals can form and grow
can lower SS by increasing urine volume

2

randall's plaque hypothesis

a model for stone formation: crystals in urine become attached to a site of crystalline deposits of interstitial calcium phosphate after loss of normal urothelium --> fixed stone that grows over time

3

geographical trends in stone

stone belt in US = southeast
- warmer temps + sunlight (increases urinary Ca++)

4

most common type of stone

calcium oxalate = 80%

5

causes of calcium oxalate stones

hypercalciuria - most common
hyperoxaluria: from increased production or absorption
hyperuricosuria: uric acid crystals
fam hx
dehydration
diet or meds: high protein, vit C and D, antacid abuse

6

cause, pathophys, tx of enteric hyperoxaluria

cause: malabsorption syndromes (crohn's disease, bypass)
pathophys: soaps bind ca in gut, more free oxalate to be absorbed
tx: PARADOXICAL Ca or Mg supplementation, tx underlying condition

7

how does high protein diet lead to calcium oxalate stones

acid generation from AA metabolism --> bone buffering of acid --> hypercalciuria + acidic urine

8

risk factors for calcium phosphate stones

hypercalciuria
alkaline urine: ex. distal RTA

9

uric acid calculi pathogenesis

hyperuricosuria
persistently acidic, concentrated urine (decreases uric acid solubility)

10

tx for uric acid stones

alkalinization of urine
fluid
tx underlying condition

11

struvite stones - what are they and how do they form

supersaturation w/ magnesium-ammonium phosphate
form in presence of urinary tract infection w/ urea-splitting organism (proteus, klebsiella, serratia, enterobacter)
alkaline urine! - suspect strive if urine pH >8

12

what type of stone is most common in women and paraplegics

struvite

13

cystine calculi - cause and clinical features

cystinuria - genetic defect
clinical features: early onset in childhold or early adolescence, fam hx, progression to renal failure

14

inhibitors of stone formation

deficiency can cause stones
- citrate: complexes w/ Ca++ to become soluble
- magnesium: complexes w/ oxalate to become soluble
- oral orthophosphate: decreases calcium absorption and excretion
- inorganic pyrophosphate

15

tx of stones

80% symptomatic stones are ureteral and most of these will pass
10-15% req intervention
- shock wave tx
- percutaneous surgery
- endoscopic procedure

16

tx of renal tubular acidosis

hydration
tx metabolic acidosis
increase citrate and K+: K-citrate

17

tx struvite stones

antibiotics
urease inhibitors
percutaneous surgery
fluids, tx underlying disease

18

cystine stone tx

high fluid intake
urine alkalinization
meds: d-penicillamine, alpha-MPG - disrupt disulfide bones in cysteine to increase solubility, but comes w/ SEs

19

tx hypercalciuria

thiazide diuretic: blocks Na-Cl transporter in DCT --> increases Ca+ reabsorption

20

pure Calcium phosphate stones - etiology

RTA
primary hyperparthyroidism