Nephrolithiasis

Types of stones and risk factors (Nat Rev 2016;2:16008)

  • Calcium (Ca oxalate > Ca phosphate): 70–90% of kidney stones (NEJM 2010;363:954)
    • Urine findings: ↑ Ca, ↑ oxalate (Ca-ox only), ↑ pH (Ca-phos only), ↓ citrate, ↓ volume
    • 2° hypercalciuria: 1° hyperparathyroidism, distal RTA, sarcoid, Li use
    • 2° hyperoxaluria: Crohn’s, ileal disease w/ intact colon, gastric bypass, pancreatic insuffic.
    • Diet: ↑ animal protein, ↑ sucrose, ↑ Na, ↓ K, ↓ fluid, ↓ fruits/vegetables, ↑ vit. C, ↓ Ca
  • Uric acid: 5–10% of kidney stones, radiolucent on plain film
    • Urine ↑ uric acid, ↓ pH (eg, from chronic diarrhea)