From the Guidelines
Outpatient treatment for kidney stones should prioritize increased fluid intake to achieve at least 2 L of urine per day to prevent recurrent nephrolithiasis. This approach is supported by the American College of Physicians (ACP) guideline, which recommends management with increased fluid intake spread throughout the day 1. The guideline suggests that this can help prevent recurrent nephrolithiasis, with a weak recommendation based on low-quality evidence.
Key Recommendations
- Increased fluid intake to achieve at least 2 L of urine per day
- Pharmacologic monotherapy with a thiazide diuretic, citrate, or allopurinol for patients with active disease in which increased fluid intake fails to reduce the formation of stones, as recommended by the ACP guideline 1
- Dietary changes, including reducing dietary oxalate, reducing dietary animal protein and other purines, and maintaining normal dietary calcium
Rationale
The ACP guideline is based on a systematic evidence review and provides recommendations for the prevention of recurrent nephrolithiasis in adults. The guideline targets decreasing concentrations of lithogenic factors and increasing the concentrations of inhibitors of stone formation. While the evidence is not strong, the recommendation to increase fluid intake is a simple and non-invasive approach that can help prevent recurrent nephrolithiasis.
Considerations
- Patients should be advised to drink 2-3 liters of water daily to maintain clear or light yellow urine
- Medical expulsive therapy with alpha-blockers like tamsulosin may be considered for stones 5-10mm in size to relax ureter muscles and facilitate stone passage
- Patients should strain their urine to catch passed stones for analysis and seek immediate medical attention for fever, uncontrolled pain, persistent vomiting, or inability to urinate
- Follow-up imaging is typically recommended within 2-4 weeks to confirm stone passage.
From the Research
Outpatient Treatment for Kidney Stones
- Outpatient treatment for kidney stones often involves medical expulsive therapy (MET) to help pass the stones, with alpha-blockers being a commonly used medication for this purpose 2, 3, 4.
- Alpha-blockers, such as tamsulosin, have been shown to increase stone clearance rates, decrease time to expulsion, and reduce the need for analgesia during stone passage 2, 3.
- The use of alpha-blockers is recommended in the conservative management of distal ureteral stones, particularly for stones 5-10 mm in size 2, 3.
- For ureteral stones ≤10 mm treated without lithotripsy, alpha-blockers have been found to increase clearance rates in meta-analyses and randomized controlled trials 3.
- Alpha-blockers may also be beneficial for patients with ureteral stones who have undergone lithotripsy, particularly for stones >10 mm in size 3, 4.
Benefits and Risks of Alpha-Blockers
- Alpha-blockers may increase stone clearance rates, but may also slightly increase the risk of major adverse events 4.
- Patients treated with alpha-blockers may experience shorter stone expulsion times, reduced need for diclofenac, and fewer hospitalizations 4.
- The need for surgical intervention appears to be similar with alpha-blocker treatment 4.
Guideline Recommendations
- Professional organizations recommend an initial evaluation to exclude concomitant infection, imaging with a non-contrast computed tomography scan, and consideration of medical expulsive therapy or surgical intervention depending on stone size and location 5.
- Increasing fluid intake is recommended to reduce the risk of recurrence 5, 6.
- Lifestyle modifications, such as increased fluid intake, and medications like thiazide diuretics, allopurinol, or citrates may be recommended for patients with recurrent calcium stones 6.