From the Guidelines
The recommended management for non-obstructing nephrolithiasis is to increase fluid intake to at least 2 L of urine per day to prevent recurrent nephrolithiasis, as recommended by the American College of Physicians (ACP) 1. This approach is based on low-quality evidence that shows increased fluid intake is associated with a reduction in stone recurrence. Some key points to consider in the management of non-obstructing nephrolithiasis include:
- Increasing fluid intake to achieve at least 2 L of urine per day, as this has been shown to reduce the risk of stone recurrence 1
- Considering pharmacologic monotherapy with a thiazide diuretic, citrate, or allopurinol in patients with active disease who do not respond to increased fluid intake, as these medications have been shown to reduce the risk of stone recurrence 1
- Dietary modifications, such as reducing sodium intake, limiting animal protein, and avoiding excessive oxalate-rich foods, may also be beneficial in preventing stone recurrence 1
- Stone analysis should be performed if stones are passed to guide prevention strategies, and follow-up imaging should be recommended at 4-6 weeks to assess for stone passage or growth. It's worth noting that the evidence for these recommendations is generally of low to moderate quality, and more research is needed to fully understand the best approaches to managing non-obstructing nephrolithiasis. However, based on the available evidence, increasing fluid intake and considering pharmacologic therapy in select patients appear to be reasonable approaches to reducing the risk of stone recurrence.
From the Research
Management of Non-Obstructing Nephrolithiasis
The management of non-obstructing nephrolithiasis involves several approaches, including:
- Watchful waiting: This approach is often recommended for asymptomatic renal stones, as the risk of stone-related events is relatively low 2, 3.
- Medical expulsive therapy (MET): MET, including the use of alpha-blockers and nifedipine, can improve stone-free rate and reduce stone expulsion time after extracorporeal shock wave lithotripsy (ESWL) 4, 5.
- Extracorporeal shock wave lithotripsy (ESWL): ESWL is a common treatment option for non-obstructing nephrolithiasis, particularly for stones larger than 8 mm 6, 4.
- Ureteroscopy with basket extraction of fragmented stones (URS-B) or ureteroscopy with laser "dusting" (URS-D): These procedures are also used to treat non-obstructing nephrolithiasis, although the choice of procedure depends on various factors, including stone size and location 2.
Factors Influencing Management
Several factors can influence the management of non-obstructing nephrolithiasis, including:
- Stone size: Larger stones are more likely to require intervention, while smaller stones may be managed with watchful waiting 2, 3.
- Stone location: Stones in the lower pole of the kidney are more likely to pass spontaneously, while stones in other locations may require intervention 3.
- Patient factors: Patients with diabetes mellitus, hyperuricaemia, or non-lower calyceal stones are at higher risk of developing stone-related events and may require more frequent follow-up 3.
Treatment Outcomes
The outcomes of treatment for non-obstructing nephrolithiasis vary depending on the approach used, with:
- Watchful waiting: Associated with a low risk of stone-related events, although some patients may experience spontaneous stone passage or stone growth 3.
- MET: Can improve stone-free rate and reduce stone expulsion time after ESWL 4, 5.
- ESWL: Effective for treating non-obstructing nephrolithiasis, although the success rate depends on stone size and location 6, 4.
- URS-B and URS-D: Can be effective for treating non-obstructing nephrolithiasis, although the choice of procedure depends on various factors, including stone size and location 2.