344.1 🎓 醫孞生版

344.1.0.1 📌 䞀頁重點

344.1.0.1.1 Epidemiology
  • Lifetime prevalence: men ~ 12%, women ~ 6%
  • Increasing globally
  • Recurrence: 50% in 10 years
  • Taiwan: high (diet + climate)
  • Peak age 30-50
344.1.0.1.2 Stone Types + Composition

344.1.1 Calcium-Based (~ 80%)

Calcium Oxalate (most common, 70-80%): - Idiopathic hypercalciuria - Hyperoxaluria - Acid urine - Common dietary risks: ↑ oxalate (spinach, rhubarb, beets, nuts, chocolate, tea)

Calcium Phosphate (~ 5-10%): - Alkaline urine (RTA Type 1) - Hyperparathyroidism - Carbonic anhydrase inhibitors

344.1.2 Uric Acid (5-10%)

  • Acid urine (pH < 5.5)
  • Hyperuricosuria (gout, high purine diet, TLS, myeloproliferative)
  • DKD with low urine NH4
  • Often radiolucent (need CT)

344.1.3 Struvite (5-10%)

  • Magnesium ammonium phosphate (MgNH4PO4)
  • “Infection stones”
  • Caused by urease-producing bacteria:
    • Proteus mirabilis
    • Klebsiella
    • Pseudomonas
    • S. aureus
  • Alkaline urine (pH > 7.5)
  • Often staghorn calculi (filling renal pelvis)

344.1.4 Cystine (1%)

  • Autosomal recessive cystinuria (SLC3A1, SLC7A9 mutations)
  • Defective tubular cystine + dibasic amino acid transport
  • Faint sweet odor of cysteine

344.1.5 Drug-Induced

  • Acyclovir
  • Indinavir, atazanavir
  • Sulfonamides
  • Triamterene
  • Methotrexate
  • Topiramate (carbonic anhydrase inhibition)
344.1.5.0.1 Risk Factors
  • Low fluid intake (most common modifiable)
  • High Na, animal protein, sugar intake
  • Dehydration
  • Family history
  • Hot climate
  • Medical conditions:
    • Hyperparathyroidism
    • Gout
    • IBD (Crohn — fat malabsorption → hyperoxaluria)
    • RTA (especially Type 1)
    • Cystinuria
    • Bariatric surgery (Roux-en-Y)
    • DM (uric acid stones)
  • Medications:
    • Topiramate
    • Vitamin C high doses (oxalate)
    • Triamterene
    • Indinavir
344.1.5.0.2 Clinical Presentation

344.1.6 Acute Renal Colic

  • Severe flank pain (sudden onset)
  • Radiation to groin (testicle in men, labia in women)
  • Writhing, can’t get comfortable
  • Hematuria (gross or microscopic)
  • Nausea, vomiting
  • Dysuria, urgency (if at UV junction)
  • Fever (if infection) — urosepsis risk!

344.1.7 Asymptomatic Stones

  • Found incidentally on imaging
  • Lower poles often
344.1.7.0.1 Diagnostic Workup

344.1.8 Imaging

Non-Contrast CT (Gold Standard): - > 95% sensitive - Identifies all stone types - Size, location, density (HU) - Hydronephrosis assessment - Radiation exposure consideration

Ultrasound: - For pediatric, pregnancy, follow-up - Less sensitive (60-80%) - Hydronephrosis well-visualized

KUB (Plain X-Ray): - 60-70% sensitive (calcium stones) - Uric acid + cystine often missed - Limited modern use

MR Urography: - Pregnancy alternative - No radiation

344.1.9 Laboratory

Acute: - UA + microscopy (hematuria, crystals — calcium oxalate “envelope”, uric acid “rhombus”, cystine “hexagon”) - BMP - CBC (if infection) - Urine culture (if pyuria) - Pregnancy test (women)

Stone Analysis (Critical): - All stones should be analyzed if possible - Determines specific cause + prevention

Metabolic Workup (After Recovery): - 24-hour urine collection: - Volume - Calcium - Oxalate - Citrate - Uric acid - Sodium - Phosphate - Magnesium - Cystine - pH - Creatinine (verify collection) - Serum: Ca, PO4, intact PTH, uric acid, electrolytes

344.1.9.0.1 Acute Management

344.1.10 Pain Control

  • NSAIDs (ketorolac IV/IM/PO) — first-line if no contraindication
  • Opioids if NSAID insufficient or contraindicated
  • Pyelocaliceal pressure relief

344.1.11 Hydration

  • IV fluids if dehydrated
  • Generous oral hydration

344.1.12 Anti-Emetics

  • Ondansetron, metoclopramide

344.1.13 Medical Expulsive Therapy (MET)

  • Tamsulosin (α-blocker) for ureteral stones 5-10 mm
  • SUSPEND trial (2015): showed no overall benefit
  • More benefit in distal ureteral stones (some)
  • Generally acceptable to try
344.1.13.0.1 Indications for Urgent Intervention
  • Obstruction + infection (urosepsis) — emergency
  • Anuria (bilateral obstruction or solitary kidney)
  • AKI worsening
  • Severe / persistent pain
  • Pregnancy with obstruction
  • Solitary functional kidney + obstruction
344.1.13.0.2 Procedures

344.1.14 Ureteroscopy with Laser Lithotripsy

  • Most common for ureteral and renal stones < 2 cm
  • Holmium:YAG laser
  • High success rate
  • Outpatient

344.1.15 Extracorporeal Shockwave Lithotripsy (ESWL)

  • Non-invasive shockwaves
  • Best for stones < 2 cm in upper urinary tract
  • Not for: pregnancy, bleeding diathesis, cystine (hard), uncorrected obstruction
  • Less effective for lower pole, large, dense stones

344.1.16 Percutaneous Nephrolithotomy (PCNL)

  • For large stones (> 2 cm), staghorn, complex
  • Access through skin
  • Higher complication rate

344.1.17 Open Surgery

  • Rarely; complex anatomy

344.1.18 Ureteral Stent

  • Bridging until definitive
  • Relieves obstruction
  • For severe obstruction + infection (with antibiotics) until lithotripsy
344.1.18.0.1 Prevention Strategies

344.1.19 General (All Stones)

  • Increased fluid intake (> 2.5 L urine output)
  • Lower Na (< 2.3 g/d)
  • Moderate protein (especially animal protein)
  • Adequate calcium dietary (do NOT restrict — paradoxically reduces stones; binds oxalate in GI)
  • Limit oxalate (spinach, rhubarb, beets, chocolate, tea, nuts)
  • Limit sucrose/fructose
  • Citrus juices (citrate)

344.1.20 Calcium Oxalate Stones

Hypercalciuria: - Thiazide diuretic (reduces urinary calcium) - Potassium citrate (alkalinize urine + bind calcium) - Low sodium

Hyperoxaluria: - Calcium with meals (binds oxalate in gut) - Low oxalate diet - Crohn / fat malabsorption: treat underlying - Primary hyperoxaluria (rare): specific therapy

Hypocitraturia: - Potassium citrate (10-30 mEq BID-TID)

344.1.21 Calcium Phosphate Stones

  • Treat hypercalcemia
  • Alkalinize cautiously
  • Treat RTA (NaHCO3)

344.1.22 Uric Acid Stones

  • Alkalinize urine (potassium citrate to pH 6.5-7.0)
  • Allopurinol (lower uric acid)
  • Low purine diet
  • Hydration

344.1.23 Struvite Stones

  • Antibiotics (eradication of urease-producing bacteria — long-term)
  • Surgical removal (PCNL for large)
  • Eradicate underlying infection
  • Acetohydroxamic acid (urease inhibitor — rarely used)

344.1.24 Cystine Stones

  • Heavy hydration (> 4 L/d)
  • Alkalinize (potassium citrate to pH > 7.5)
  • Cysteine-binding drugs: penicillamine, tiopronin
  • Low Na, low protein

344.1.25 Drug-Induced

  • Stop drug
  • Specific approach
344.1.25.0.1 Specific Conditions

344.1.26 Primary Hyperparathyroidism

  • Hypercalcemia + hypercalciuria + stones
  • Surgery (parathyroidectomy)

344.1.27 Distal RTA

  • Calcium phosphate stones
  • Treat acidosis (NaHCO3, potassium citrate)
  • Identify cause

344.1.28 IBD / Crohn

  • Fat malabsorption → enteric hyperoxaluria
  • Treat IBD
  • Calcium with meals
  • Cholestyramine (bind bile acids)

344.1.29 Bariatric Surgery

  • Roux-en-Y: hyperoxaluria
  • Calcium supplementation
  • Hydration

344.1.30 Pediatric Stones

  • Increasing
  • Often metabolic abnormality
  • Imaging: ultrasound first
  • Genetic causes
344.1.30.0.1 Pregnancy + Stones
  • ~ 1 in 1500
  • US first-line imaging
  • MR if needed
  • Conservative when possible
  • Stent if severe obstruction + infection
  • Lithotripsy avoided

344.1.30.1 🩺 床邊速查

  • Acute renal colic: severe flank pain → groin; hematuria
  • CT non-contrast: gold standard (all stone types)
  • Stone passage: < 5 mm 80%; 5-10 mm 50%; > 10 mm < 25%
  • Pain: NSAIDs (ketorolac) first; opioids if needed
  • MET (tamsulosin): acceptable for 5-10 mm ureteral
  • Urgent intervention: obstruction + infection (urosepsis); AKI; solitary functional kidney
  • Calcium oxalate: most common; thiazide + K citrate
  • Uric acid: alkalinize + allopurinol
  • Struvite: urease bacteria; surgical + antibiotics
  • Cystine: hydration + alkalinization + tiopronin