Kidney Stone Management: How Nephrologists Guide Prevention and Treatment

Nephrologists specialize in medical (non-surgical) kidney stone management—prevention, dissolution, and coordinating surgical referral when needed.

1. Diagnosis and Risk Stratification

• Imaging: Non-contrast CT (gold standard), ultrasound (pregnancy, recurrent)
• Stone analysis (if passed/retrieved): Calcium oxalate (80%), calcium phosphate, uric acid, struvite, cystine
• 24-hour urine metabolic panel: Volume, pH, calcium, oxalate, citrate, uric acid, sodium, supersaturation ratios
• Serum studies: Calcium, PTH, uric acid, electrolytes, bicarbonate, renal function

2. Medical Management

• Acute pain: NSAIDs first-line (ketorolac, diclofenac); opioids if refractory
• Medical expulsive therapy (MET): Tamsulosin (α-blocker) for distal ureteral stones 5–10 mm
• Infection: Antibiotics guided by culture; obstruction + infection = emergency decompression
• Dissolution therapy: Uric acid stones → urinary alkalinization (potassium citrate, target pH 6.5–7); cystine stones → high fluid + alkalinization + thiol drugs

3. Prevention: Dietary and Lifestyle

• Fluid: ≥2.5–3 L/day urine output (spread throughout day)
• Sodium: <2.3 g/day (high Na⁺ → ↑ calciuria)
• Animal protein: Moderate (↑ uric acid, ↓ citrate)
• Oxalate: Limit high-oxalate foods (spinach, nuts, beets) IF hyperoxaluria; pair with calcium-rich foods to bind oxalate in gut
• Calcium: Dietary calcium 1000–1200 mg/day (supplements may ↑ stones)
• Citrate: Citrus fruits, potassium citrate if hypocitraturia

4. Pharmacologic Prevention (Based on 24-hr Urine)

• Thiazides: Hypercalciuria
• Potassium citrate: Hypocitraturia, uric acid/cystine stones
• Allopurinol/febuxostat: Hyperuricosuria
• Thiol drugs (tiopronin, penicillamine): Cystinuria
• Acetohydroxamic acid: Struvite (urease-producer) stones

5. Surgical Coordination

• Refer to urology for: Stones >10 mm, failed MET, obstruction + infection, intractable pain, anatomic abnormalities
• Procedures: SWL, ureteroscopy (URS), PCNL

6. Long-Term Surveillance

• Repeat imaging (ultrasound/KUB) per risk
• Periodic 24-hour urine to adjust therapy
• Recurrence rate 50% at 10 years without prevention

Nephrologists are the architects of stone prevention—addressing the metabolic "soil" from which stones grow.