Treatment of Kidney Stones
The treatment of kidney stones depends primarily on stone size, location, and symptoms, with options ranging from conservative management with high fluid intake for small stones to surgical interventions for larger stones or those causing obstruction.
Initial Assessment and Management
- Stone size and location determine treatment approach:
| Stone Size | Stone Location | Recommended Treatment |
|---|---|---|
| <10 mm | Ureter | Observation or Medical Expulsive Therapy (MET) |
| <10 mm | Renal pelvis or upper/middle calyx | Shock Wave Lithotripsy (SWL) or flexible Ureteroscopy (URS) |
| 10-20 mm | Renal pelvis or upper/middle calyx | SWL or flexible URS |
| <10 mm | Lower pole | Flexible URS or SWL |
| 10-20 mm | Lower pole | Flexible URS or Percutaneous Nephrolithotomy (PCNL) |
| >20 mm | Any location | PCNL [1] |
- For asymptomatic, non-obstructing stones up to 15 mm, active surveillance with regular imaging is recommended 1
- Diagnostic workup should include urinalysis, serum chemistries, and imaging (non-contrast CT or renal ultrasound) 1
Conservative Management
- For small stones (<10 mm), especially in the ureter, initial management includes:
- High fluid intake to produce 2-2.5 liters of urine daily (requiring 3.5-4 liters of fluid intake) 1, 2
- Pain management with NSAIDs as first-line therapy 3
- Medical Expulsive Therapy (MET) with tamsulosin 0.4 mg daily to facilitate stone passage 1
- Tamsulosin increases stone passage rates by approximately 29% compared to controls
- Benefits include reduced stone passage time and decreased pain during passage 1
Surgical Interventions
- Surgical options are indicated when stones fail to pass spontaneously or with MET, based on size and location:
- Shock Wave Lithotripsy (SWL): First-line for stones <20 mm in renal pelvis or upper/middle calyx
- Ureteroscopy (URS): Alternative to SWL, especially for lower pole stones
- Percutaneous Nephrolithotomy (PCNL): Preferred for stones >20 mm or complex stones 1
Prevention of Recurrence
Dietary Modifications
- Maintain adequate hydration (3.5-4 liters daily) to produce >2 liters of urine 1, 2
- Normal dietary calcium intake (1,000-1,200 mg/day) is recommended (low calcium diets paradoxically increase stone risk) 1, 4
- Reduce sodium intake to <2,300 mg/day 1, 4
- Limit animal protein intake to 0.8-1.0 g/kg body weight/day 4, 5
- Increase consumption of fruits and vegetables, especially citrus fruits 1, 4
- Limit intake of foods high in oxalate 1, 5
Pharmacological Prevention
Based on metabolic abnormalities:
For infection stones (struvite):
Metabolic Evaluation
- Recommended for high-risk patients and all recurrent stone formers 1
- 24-hour urine collection to evaluate metabolic parameters (volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine) 1
- Stone analysis should be performed at least once using methods such as Fourier-transform infrared spectroscopy (FT-IR) or X-ray diffraction (XRD) 1
Special Considerations
- Comorbidities: Manage associated conditions like obesity, hypertension, diabetes, and recurrent UTIs 1
- Pregnancy: Ultrasound is preferred imaging modality 3
- Elderly patients: Consider bone health when recommending calcium intake; be cautious with sodium restriction due to hemodynamic sensitivity 4
Common Pitfalls to Avoid
- Restricting dietary calcium (increases stone risk)
- Inadequate fluid intake (cornerstone of prevention)
- Failing to obtain stone analysis (guides preventive measures)
- Overlooking metabolic evaluation in recurrent stone formers
- Using potassium citrate cautiously in patients with renal insufficiency or those taking medications that increase potassium levels 1