Urinary Calculi

Introduction & Risk Factors - Stone Genesis Saga

• Urinary calculi: Solid crystalline concretions in urinary tract (kidney, ureter, bladder).
• Epidemiology: India's "stone belt" (NW states); Peak 20-50 yrs; M:F ≈ 3:1.
• Risk Factors:
  • ↓Fluid intake (key preventable factor)
  • Diet: ↑Oxalate, ↑Na, ↑Animal protein
  • Metabolic: Hypercalciuria, hyperuricosuria, hypocitraturia, hyperoxaluria
  • Anatomical: PUJO, horseshoe kidney, medullary sponge kidney
  • Genetic: Cystinuria, RTA Type 1, primary hyperoxaluria
  • Medications: Triamterene, indinavir, topiramate

⭐ Most common cause of hypercalciuria is idiopathic hypercalciuria.

Types of Calculi - Crystal ID Parade

• 📌 Mnemonic (Radiolucent stones): Uric Acid, Xanthine, Indinavir (UXI). (Xanthine & Indinavir are rare).

⭐ Struvite stones are associated with urea-splitting organisms like Proteus and can form large staghorn calculi.

Clinical Features - Colic & Clues

• Renal/Ureteric Colic:
  • Loin pain radiating: groin, tip of penis, labia.
  • Severe, colicky.
• Associated Symptoms:
  • Hematuria (microscopic/macroscopic).
  • Nausea/Vomiting.
  • Dysuria, urgency, frequency.
• Bladder Stones: Irritative voiding, intermittent stream.
• Signs:
  • Costovertebral angle (CVA) tenderness.
  • Abdominal tenderness.
  • Systemic: fever, chills (if infection).
• Silent Stones: Incidental finding.

⭐ The character of pain in renal colic is typically crescendo-decrescendo, and patients are often restless (unable to find a comfortable position).

Diagnosis - Spotting the Stones

• Initial Clues:
  • Hx, Exam.
  • Urine: Hematuria, pyuria, crystals, pH.
  • Blood: CBC (↑WBC), RFT, electrolytes, S.Ca, S.Uric acid.
• Imaging - Visualizing Stones:
  • X-ray KUB: Radio-opaque stones (CaOx, Struvite).
  • USG KUB: Hydronephrosis, stones (kidney, prox. ureter, VUJ). Initial choice, esp. pregnancy/children.
  • NCCT KUB: Gold Standard. Detects most stones (not pure Indinavir), size, location, HU, obstruction.

    ⭐ NCCT KUB is the gold standard for detecting urinary calculi.

  • IVU: Historical; anatomy & function.
• Metabolic Workup:
  • Recurrent/high-risk: 24-hr urine (Ca, Oxalate, Citrate, Uric acid, Na, Volume, Cr).

Management & Prevention - Shatter & Shield

• Conservative: Hydration (>2.5L/day urine), Analgesia, watchful wait (stones <5mm).
• MET: Distal ureteric stones 5-10mm. Tamsulosin 0.4mg OD.
• Surgical (Indications: severe pain, obstruction/infection, RF, large/unsuitable stones):
  • ESWL: Renal <2cm, upper ureter <1cm. CI: pregnancy, bleeding, UTI.
  • URS: Mid/distal ureteric. Renal if ESWL/PCNL unsuitable.
  • PCNL: Renal >2cm, staghorn, lower pole >1.5cm, failed ESWL/URS.
  • Open/Lap/Robotic: Rare; complex, failed MIS.

• Prevention: Diet (by stone type), ↑fluid intake. Meds: Thiazides (hypercalciuria), Allopurinol (hyperuricosuria), K-Citrate (hypocitraturia/uric acid).

⭐ For large renal stones (>2 cm) or staghorn calculi, Percutaneous Nephrolithotomy (PCNL) is generally the first-line treatment.

High‑Yield Points - ⚡ Biggest Takeaways

• Calcium oxalate stones are most common; often envelope-shaped crystals.
• Struvite stones (MAP) are linked to UTIs by urease-producing bacteria (e.g., Proteus); can form staghorn calculi.
• Uric acid stones are radiolucent on X-ray; treat with urine alkalinization (e.g., potassium citrate).
• Cystine stones indicate cystinuria (autosomal recessive); hexagonal crystals pathognomonic.
• Non-Contrast CT (NCCT) KUB is the gold standard for diagnosing most urinary calculi_