KIDNEY STONES. Epidemiology. Affects 5-10% of Americans in their lifetime Chance of recurrence is about 50% Men are more often affected than women Average age of onset is between 20 and 30 years. Types and their causes. Calcium oxalate and phosphate:
- Account for about 70% of stones.
- Causes include hypercalciuria,
hyperuricosuria, hyperoxaluria, etc
Magnesium Ammonium Phosphate:
- 15-20% of stones
- caused by urea-splitting bacteria Proteus and some
- Form the Staghorn calculi
- 5-10% of stones
- Predisposed with gout, leukemias, or ???
- Only 1-2% of stones
- Caused by genetic defects in renal
reabsorption of amino acids.
Noncontrast CT scans are now the modality of choice
1)elimination of contrast
2)no need for bowel prep
3) can see noncalcified stones
4) less expensive than IVP
5) does not require experienced radiologic technician.
Classic diagnostic test of choice
1) Can document nephrolithiasis and upper-tract anatomy
2) Oblique views can diff between gallstones and renal stones on the right.
1) Bowel prep
2) Reactions to contrast
3) Can take a really long time
Will reveal calculus in up to 80% of cases
Stones must generally be at least 2mm in diameter
Stones must contain calcium to be visible
Useful if patient is pregnant or has contraindication to IVP
When used with KUB can be as effective as IVP