344.2 🩺 國考版

344.2.1 高頻考點

344.2.1.1 Stone Types

  • Calcium oxalate ~ 70-80% (most)
  • Calcium phosphate 5-10%
  • Uric acid 5-10%
  • Struvite 5-10%
  • Cystine 1%
  • Drug-induced

344.2.1.2 Diagnosis

  • Non-contrast CT: gold standard
  • US for pregnancy/pediatric
  • KUB limited

344.2.1.3 Stone Passage by Size

  • < 5 mm: 80%
  • 5-10 mm: 50%

  • 10 mm: < 25%

344.2.1.4 Acute Management

  • Pain: NSAID (ketorolac), opioid backup
  • Hydration
  • MET (tamsulosin) for 5-10 mm distal ureteral (mixed evidence — SUSPEND 2015 neg)
  • Anti-emetics

344.2.1.5 Urgent Intervention

  • Obstruction + infection (urosepsis emergency!)
  • AKI
  • Severe pain
  • Solitary kidney + obstruction
  • Pregnancy + complications

344.2.1.6 Procedures

  • Ureteroscopy + laser lithotripsy (most ureteral / renal < 2 cm)
  • ESWL (small upper urinary stones; not for pregnancy, cystine, bleeding)
  • PCNL (large, staghorn)
  • Stent (bridging)

344.2.1.7 Stone Composition + Specific Prevention

Calcium Oxalate: - Hypercalciuria: thiazide - Hyperoxaluria: calcium with meals - Hypocitraturia: potassium citrate

Uric Acid: - Alkalinize urine (potassium citrate to pH 6.5-7.0) - Allopurinol

Struvite: - Antibiotics (urease bacteria — Proteus, Klebsiella, Pseudomonas, S. aureus) - Surgical removal (PCNL)

Cystine: - Hydration (> 4 L/d) - Alkalinize (pH > 7.5) - Tiopronin, penicillamine

344.2.1.8 Crystals on UA

  • Calcium oxalate: “envelope” shaped
  • Uric acid: rhombus, needle
  • Struvite: coffin-lid (rectangular)
  • Cystine: hexagonal

344.2.1.9 Metabolic Workup

  • 24-hour urine: volume, Ca, oxalate, citrate, uric acid, Na, pH, creatinine
  • Serum: Ca, intact PTH, uric acid, electrolytes

344.2.1.10 Dietary Recommendations

  • Increase fluid (> 2.5 L urine)
  • Lower Na
  • Adequate dietary Ca (don’t restrict!)
  • Lower oxalate
  • Moderate protein
  • Citrus juices

344.2.1.11 Recurrence Prevention

  • 50% recurrence within 10 years
  • Stone analysis + metabolic workup essential

344.2.1.12 Key Trials

  • SUSPEND (2015): tamsulosin vs placebo for ureteral stones — overall negative

344.2.2 易混淆比范

Stone Type % pH Imaging Bacteria Prevention
Ca oxalate 70-80 Variable CT None Thiazide, K citrate, ↑ fluid
Ca phosphate 5-10 Alkaline CT None K citrate (cautious)
Uric acid 5-10 < 5.5 CT (radiolucent on KUB) None Alkalinize, allopurinol
Struvite 5-10 > 7.5 CT Urease bacteria Antibiotics + surgery
Cystine 1 Variable CT (radiopaque, dense) None Hydration + alkalinize + tiopronin
Drug Variable Variable CT None Stop drug

344.2.3 Special Topics

344.2.3.1 Enteric Hyperoxaluria

  • Fat malabsorption (Crohn, bariatric surgery, pancreatic insufficiency)
  • Mechanism: fat binds calcium in gut → oxalate absorbed
  • Treatment: calcium with meals + cholestyramine

344.2.3.2 Primary Hyperoxaluria

  • AGXT, GRHPR, HOGA1 mutations
  • Severe; ESKD
  • Lumasiran (Oxlumo, FDA 2020) — siRNA for AGXT
  • Nedosiran — RGRPR siRNA emerging
  • Liver-kidney transplant

344.2.3.3 Cystine Stones

  • Autosomal recessive
  • Pediatric / young adult onset
  • Recurrent
  • Hydration > 4 L/d
  • Tiopronin preferred over penicillamine