Nephrolithiasis

Nephrolithiasis

 

Nephrolithiasis is a worldwide problem that accounts for significant morbidity and cost.

Epidemiology

  • Prevalence
    • 5-10% of the population is affected, 50% recurrence rate
  • Age – peak 20-30 years
  • Gender – M>F
  • Ethnicity – Caucasian men have highest incidence

Pathophysiology

  • Calcium oxalate/calcium phosphate stones are the most common (70-90%)
    • Risk factors include dehydration, thiazide diuretics, increased intestinal absorption, excessive oxalate consumption, pregnancy, primary hyperparathyroidism, chronic bowel malabsorption and chronic use of calcium containing products
  • Uric acid stones (5-15%)
    • Risk factors include gout, familial history, malignancy treated with chemotherapy, high purine diet
  • Magnesium ammonium phosphate stones (10-15%)
    • Risk factors include frequent urinary tract infections and presence of alkaline urine
    • Also referred to as struvite stones (staghorn calculi)
  • Cystine stones (1-2%)
    • Risk factor is hereditary cystinuria

Clinical Presentation

  • Acute, colicky flank pain radiating into the groin and scrotum associated with nausea and vomiting
  • Urinary urgency, frequency and dysuria may develop with stone passage
  • Hematuria is present in 90% of patients

Diagnosis

  • Laboratory testing
    • Urine – urinalysis, kidney stone risk assessment
      • Amino acids analysis to rule out cystinuria
    • Serum – urea nitrogen, creatinine, uric acid, ionized calcium and PTH
    • Stone – calculi analysis
  • Imaging studies
    • Helical CT scan can confirm presence and location of stones

Disease Monitoring 

  • Usually includes:
    • Urine – kidney stone risk assessment
      • Quantitative cystine in patients with cystinuria
    • Serum – urea nitrogen, creatinine and ionized calcium

See Also