Evaluation and Treatment of Renal Stones
1) Finding them:
Noncontrast spiral CT scan better and quicker than IVP
Then:
KUB
Ultrasound of abdomen and pelvis
To look for stones < 5 mm
2) Expulsion:
Flomax,a-blocker (tamsulosin) relaxes ureter tone which
aids stone passage but best for stones < 6 mm but tried for
stones 10 mm or <.
Pain control may be just as good with NSAID’S like Toradol
as it is with Narcotics even as outpatient.
3) Workup:
Recovered stone can be sent off for analysis so that we can
know what it’s made of:
Blood tests: Chem 8,phosphorus,PTH,uric acid,25-OH Vit D
and 1,25-diOH Vit D levels
UA with C&S
24 hour urine for: Calcium nl men <250mg;women <200mg
: Uric acid
: Oxalate nl <40mg
: Citrate nl men >450mg;women >500mg
: Cysteine
(197)
4) Treatment:
Absorptive hypercalciuria:from increased intestinal calcium
absorption or PTH deficiency causing increased urinary
calcium concentrations
Type I
Type II
Type III
(diet neutral)
Tx thiazide or Tums
(diet dependent) Tx protein/salt restriction
or Tums
(renal phosphate leak-decreased serum
phosphorus with increased urine calcium)
Tx thiazide
Resorptive hypercalcuria:from excess PTH secretion due to
a pituitary adenoma
Tx parathyroid resection
Renal hypercalcuiria:from renal insensitivity to PTH causing
a secondary hyperparathyroidism just to maintain normal
serum calcium at expense of increased urine calcium
Tx thiazide &Tums
(This Tx wasn’t in text but would boost serum calcium and
exert a negative feedback on PTH secretion-could work)
Hyperuricosuria/Gouty diathesis:from increased uric acid
levels in acidic urine as with high purine diets or with chemtherapy.In this case both uric acid and calcium oxalate stones
form, so the Tx involves alkalizing the urine with K+ citrate
or Na+ bicarbonate as well as Allopurinol or Uloric
(198)
Hyperoxaluria:from urine oxalate >40mg in 24 hr urine due
to overabsorption of oxalates from GI tract following small
bowel resection or chronic diarrheal states where calcium is
either absorbed or excreted too quickly to bind with oxalate
so that the then calcium oxalate can be excreted safely in the
stool rather than precipitating as renal stones.
Tx Tums (Ca2+ to bind oxalate)
(avoid tea,draft beer and black olives)
Hypocitrauria:from lack of urinary citrate which is >450mg in
men and >500mg in women that inhibits stone formation by
complexing with calcium.Often occurs when patient is acidic
which causes increased renal citrate reabsorption and less
citrate synthesis.
Tx Bicitra to alkalinize urine and oppose
Acidosis
Renal tubular acidosis:from inability to acidify urine or inability to reabsorb bicarbonate.
Type I
distal
inability to acidify urine
promotes bone & citrate reabsorption
Type II proximal inability to reabsorp bicarbonate
causes bicarbonate and citrate wasting
Tx Bicitra and Tums because patient needs
more calcium and acid neutralization
Infectious stones:from urease splitting bacteria:Proteus,Klebsiella and Pseudomonas that produce magnesium ammonium
phosphate stones. Tx treat infection and confirm clearance
(199)
Cystinuria:from genetic disorder of basic amino acid reabsorption in the proximal tubule.
Tx keep well hydrated
* 3 oz’s of lemon juice in water with added
sugar for taste provides 63 meq’s of citrate to
prevent stones from forming*
(200)