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