Nephrolithiasis, or kidney stones, are common in the United States, affecting around 13% of men and 7% of women. They are formed from substances like calcium, uric acid, cystine, and struvite. Risk factors include gout, UTIs, family history, certain medications, and diet. Symptoms include flank pain, hematuria, and urinary symptoms. Diagnosis involves urinalysis, imaging like ultrasound or CT. Treatment depends on the stone composition but may include increased fluid intake, diet changes, medications, or surgical removal procedures like lithotripsy. Without treatment, stones less than 5mm often pass spontaneously but larger stones usually require removal to prevent reoccurrence or complications

1. NephrolithiasisPatrick Carter MPAS, PA-CClinical Medicine IMarch 14, 2011

2. Objectives For nephrolithiasis, describe the:EtiologyEpidemiologyPathophysiologyRisk factorsSigns and symptomsDiagnostic work-upTreatment

3. Nephrolithiasis

4. NephrolithiasisOne of the most common urological problems in the US~13% of American men~7% of American women Prevalence is increasing throughout the industrialized world

5. NephrolithiasisConstituents of renal stonesUric acidCystineStruvite (MgNH4PO4) Calcium oxalate and calcium phosphate stones make up 75–85%

6. NephrolithiasisCalcium stones More common in menAverage age of onset is in the 20’s or 30’s50% of patients will form another within the next 10 years, usually one every 2-3 years

7. NephrolithiasisUric acid stones 5–10% of kidney stonesAlso more common in menHalf of patients also have goutUsually familial Cystine stones Uncommon, only ~1% of cases

8. NephrolithiasisStruvite stones Common and potentially dangerousMainly in women or patients who require chronic bladder catheterization Result from UTI’s with urease-producing bacteria (Proteus species)Can produce a large stone with a "staghorn" appearance

9. Staghorn Stones

10. NephrolithiasisEpidemiologyThird most common type of renal disease after UTI and prostate disease240,000–720,000 Americans per yearMen > women 3-4:1More common in areas of high humidity and elevated temperaturesMore common in the summer

11. NephrolithiasisRisk factorsGoutChronic UTI’sFamily historyMedicationsAntacidsLoop diureticsVitamin C in large dosesEtOH

12. Acute NephrolithiasisSigns and symptomsMay be asymptomaticFlank pain with radiation to testicle or vulvaPain is often severe and patient cannot stay in one positionHematuriaFrequency, urgency +/- dysuriaCVA tenderness

13. Acute NephrolithiasisDiagnostic studiesStone analysis if any stones recoveredUrinalysis for hematuria, pyuria, crystals, altered pHpH < 5 correlated with uric acid or cystine stonespH > 7.5 is suggestive of struvite stonesKUB x-ray will show calcium, struvite and cystine stonesRenal ultrasoundCT Scan is imaging is 1st line

14. KUB X-Ray

15. IV Pyelogram

16. CT Scan

17. Acute NephrolithiasisTreatmentInitial management  fluids and analgesicsMost stones < 5 mm will pass spontaneouslyStrain urine for stones

18. Acute NephrolithiasisTreatmentIndications for stone removalIntractable painSevere obstructionSerious bleedingInfectionStones > 10 mm

19. Acute NephrolithiasisTreatmentMethods of stone removalRetrograde passage of a flexible basketPyelolithotomy and ureterolithotomyLithotripsyExtracorporealPercutaneousEndoscopic

20. Specific TreatmentsCalcium stonesHypercalciuriaLow-sodium and low-protein dietThiazide diureticHyperuricosuriaLow-purine dietAllopurinol 100 mg PO twice dailyPrimary hyperparathyroidism  parathyroidectomy

21. Specific TreatmentsCalcium stonesHyperoxaluriaLow-oxalate dietCholestyramine – binds oxalateUric acid stonesPotassium citrate to raise urine pHLow-purine dietAllopurinol

22. Specific TreatmentsCystine stonesHigh fluid intake > 3 L per dayLow-salt dietRaising urine pH > 7.5Struvite stonesComplete removal of the stone followed by sterilization of the urinary tractIf cannot tolerate surgery, acetohydroxamic acidLimited by side effectsHeadache tremor, thrombophlebitis

23. Questions?