From the Guidelines
For several punctate nonobstructing renal calculi less than 5mm, conservative management is recommended. This approach prioritizes minimizing morbidity, mortality, and optimizing quality of life, as the risk of complications from surgical intervention may outweigh the benefits for small, asymptomatic stones 1. The most recent and highest quality study supports active surveillance for stones up to 15 mm, with follow-up imaging as recommended by AUA/ES and EAU guidelines 1.
Key aspects of conservative management include:
- Increasing fluid intake to at least 2-3 liters of water daily to maintain dilute urine and prevent stone growth
- Taking over-the-counter pain medications like ibuprofen (400-600mg every 6-8 hours) or acetaminophen (500-1000mg every 6 hours) as needed for discomfort
- Implementing dietary modifications, such as reducing sodium intake to less than 2300mg daily, limiting animal protein, avoiding excessive oxalate-rich foods, and maintaining normal calcium intake from dietary sources
- Straining urine to catch any passed stones for analysis, which helps determine stone composition and guides future prevention strategies
- Following up with a healthcare provider in 4-6 weeks for reassessment
It is essential to note that while ultrasound (US) can be used for initial evaluation, its sensitivity for detecting small stones (≤5 mm) is limited, and stone size estimation may be inaccurate compared to CT 2. However, US can be useful in detecting signs of obstruction, such as hydronephrosis, and can be combined with radiography to improve stone detection. If severe pain, fever, nausea, vomiting, or inability to urinate develops, immediate medical attention is necessary, as these symptoms may indicate complications like obstruction or infection 1, 2.
From the Research
Treatment of Renal Calculus
- The treatment of renal calculus, particularly those less than 5mm in size, can be managed through various methods, including extracorporeal shock wave lithotripsy (ESWL) and medical therapy with potassium citrate 3, 4.
- ESWL is a common treatment for renal stones, with a high success rate for low-density stones (< 500 Hounsfield units) and smaller stone sizes 5, 6.
- The use of potassium citrate therapy has been shown to improve stone clearance rates and prevent residual fragment growth or reaggregation in patients with residual fragments after ESWL 3, 4.
Factors Affecting Treatment Outcomes
- Stone density, size, and location are significant factors affecting ESWL treatment outcomes, with higher density stones, larger stone sizes, and stones located in the lower calyceal area having lower success rates 5, 6.
- The combination of stone density and size accounts for nearly 73% of the variation in the number of shock waves required to attain fragmentation 5.
- Stone density on native CT scans can be used as a predictor of treatment outcomes in ESWL, with lower stone densities associated with higher clearance rates 6.
Medical Therapy
- Potassium citrate therapy can be used to prevent stone recurrence and regrowth after ESWL, particularly in patients with residual fragments 3, 4.
- The use of alkaline citrate therapy has been shown to improve residual stone fragment clearance and prevent growth or reaggregation in patients with sterile calcium and infection nephrolithiasis 4.
- Combined treatment with EDTA potassium citrate and ESWL has been used to successfully dissolve renal calculi in patients with medullary sponge kidney 7.