How to manage a kidney stone?

Management of Kidney Stones

The cornerstone of kidney stone management includes increasing fluid intake to achieve at least 2.5 liters of daily urine output, maintaining adequate dietary calcium (1,000-1,200 mg/day), limiting sodium intake (≤2,300 mg/day), and using targeted medical therapy based on stone composition and metabolic abnormalities. 1

Initial Management of Kidney Stones

Acute Management

1. Pain Management

   • First-line: NSAIDs for pain control 2
   • Adequate hydration unless contraindicated

2. Medical Expulsive Therapy (MET)

   • Recommended for uncomplicated ureteral stones ≤10 mm, particularly distal ureteral stones
   • Alpha-blockers are the medication of choice
   • Patients should be counseled about side effects and "off-label" use 1

3. Observation vs. Intervention

   • For ureteral stones <10 mm with controlled symptoms: observation with periodic evaluation
   • For ureteral stones >10 mm: surgical intervention typically required 1

Surgical Management Options

Based on stone size and location:

Stone Size	Stone Location	Recommended Treatment
<10 mm	Ureter	Observation or MET
<10 mm	Renal pelvis or upper/middle calyx	SWL or flexible URS
10-20 mm	Renal pelvis or upper/middle calyx	SWL or flexible URS
10-20 mm	Lower pole	Flexible URS or PCNL
>20 mm	Any location	PCNL

SWL = Shock Wave Lithotripsy; URS = Ureteroscopy; PCNL = Percutaneous Nephrolithotomy 1

Prevention of Recurrence

Diagnostic Evaluation

• Stone analysis at least once when available
• Two 24-hour urine collections analyzing:
  • Total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine
  • Additional measurement of urinary cystine for patients with suspected cystinuria 1

Fluid Intake

• Target urine output of at least 2.5 liters daily 1, 3, 4
• Recommended beverages:
  • Water (primary source)
  • Coffee, tea, wine, beer, and orange juice (associated with lower stone risk)
• Beverages to avoid:
  • Sugar-sweetened sodas
  • Grapefruit juice (may increase stone risk by 40%) 1

Dietary Recommendations

1. Calcium Intake

   • Maintain adequate calcium intake (1,000-1,200 mg/day)
   • Avoid calcium restriction as it may increase oxalate absorption and stone risk 1, 4, 5

2. Sodium Restriction

   • Limit sodium intake to ≤2,300 mg/day
   • High sodium increases urinary calcium excretion 1, 5

3. Animal Protein

   • Reduce non-dairy animal protein to 5-7 servings per week
   • Limit to 0.8-1.0 g/kg body weight/day 1, 5

4. Oxalate Management

   • Avoid high-oxalate foods for patients with high urinary oxalate
   • High-oxalate foods include nuts, certain vegetables, wheat bran, rice bran, chocolate, tea, rhubarb, and strawberries
   • Not necessary for pure uric acid stones or normal urinary oxalate excretion 1

5. Potassium-Rich Foods

   • Increase intake of potassium-rich foods
   • Increases urinary citrate excretion and reduces urinary calcium excretion 1

6. Carbohydrates

   • Reduce sucrose/carbohydrate intake
   • Carbohydrate ingestion increases urinary calcium excretion 1

Medical Therapy Based on Stone Type

1. Calcium Oxalate Stones

   • Thiazide diuretics for hypercalciuria
   • Potassium citrate for hypocitraturia
   • Allopurinol for hyperuricosuria 1, 3

2. Uric Acid Stones

   • Urinary alkalinization
   • Allopurinol for hyperuricosuria 3

3. Cystine Stones

   • Urinary alkalinization
   • Adequate fluid intake
   • Tiopronin if the above measures are insufficient 3

4. Struvite Stones

   • Complete surgical removal
   • Appropriate antibiotic therapy 3

5. Primary Hyperoxaluria

   • Pyridoxine (vitamin B6) supplementation at 5 mg/kg (maximum)
   • Assess responsiveness after 2 weeks (>30% decrease in urinary oxalate)
   • Consider RNA interference therapy for non-responders or severe cases 1

Monitoring and Follow-up

• Repeat 24-hour urine collections:
  • Every 3-6 months during the first year of therapy
  • Every 6 months thereafter
• Monitor urinary oxalate, citrate, calcium, and pH
• Assess for crystalluria to evaluate therapeutic efficacy 1

Common Pitfalls to Avoid

1. Calcium restriction - This can actually increase stone risk by increasing oxalate absorption 1, 4
2. Inadequate fluid intake - The most important preventive measure is achieving adequate urine volume 1, 3, 6
3. Failure to identify metabolic abnormalities - Comprehensive metabolic evaluation is essential for targeted therapy 1
4. Overlooking medication-induced stones - Various medications can contribute to stone formation 2
5. Ignoring anatomical abnormalities - These can predispose to stone formation and may require specific interventions 2