From the Guidelines
No, asymptomatic patients with a history of kidney stones and crystals on urinalysis generally do not require immediate treatment. The focus should be on preventive measures to reduce the risk of recurrent nephrolithiasis, as recommended by the American College of Physicians 1. This includes increasing fluid intake to achieve at least 2 L of urine per day, which can help prevent the formation of stones.
Some key considerations for preventive measures include:
- Increasing fluid intake spread throughout the day to achieve at least 2 L of urine per day, as recommended by the ACP 1
- Dietary modifications based on stone composition, such as limiting sodium, animal protein, and oxalate-rich foods for calcium oxalate stones
- Regular follow-up monitoring to assess the effectiveness of preventive measures and adjust as needed
Specific preventive medications may be considered based on recurrence risk and stone type, such as thiazide diuretics for calcium stones, potassium citrate for hypocitraturia, or allopurinol for uric acid stones, as outlined in the ACP guideline 1. However, these should be considered on a case-by-case basis, taking into account the patient's individual risk factors and medical history. The presence of crystals alone without symptoms represents a risk factor rather than an acute condition requiring treatment, and the clinical approach should focus on preventing stone formation through addressing underlying metabolic abnormalities and lifestyle factors.
From the FDA Drug Label
Allopurinol tablets are indicated in: ... the management of patients with recurrent calcium oxalate calculi whose daily uric acid excretion exceeds 800 mg/day in male patients and 750 mg/day in female patients Therapy in such patients should be carefully assessed initially and reassessed periodically to determine in each case that treatment is beneficial and that the benefits outweigh the risks. The patient has a history of kidney stones with crystals on urinalysis but is asymptomatic. Treatment is not explicitly recommended for asymptomatic patients. The decision to treat should be based on individual assessment, considering the benefits and risks, and the presence of specific conditions such as excessive uric acid excretion 2.
- The patient's uric acid excretion levels are not provided.
- The patient is asymptomatic. No treatment is recommended unless the benefits outweigh the risks and the patient meets specific criteria.
From the Research
Treatment of Asymptomatic Kidney Stones with Crystals on Urinalysis
- The decision to treat asymptomatic kidney stones with crystals on urinalysis depends on the type of stone and the patient's individual risk factors 3, 4.
- For uric acid stones, treatment with urinary alkalinization using potassium citrate or sodium bicarbonate can be effective in dissolving existing stones and preventing recurrence 3, 5.
- However, for calcium oxalate stones, the treatment approach is more complex, and potassium citrate may not be effective in preventing stone formation 6.
- In some cases, acetazolamide may be used as an adjunct to potassium citrate for urinary alkalization in patients with uric acid and cystine stone formation recalcitrant to potassium citrate alone 7.
Considerations for Treatment
- The patient's urine pH, volume, and composition should be evaluated to determine the best course of treatment 3, 4.
- A low-purine diet may be recommended to reduce urinary uric acid excretion 3.
- Patients with a history of kidney stones should be encouraged to stay hydrated and maintain a urine volume above 2000 ml daily 3, 5.
- Regular follow-up and monitoring of urine studies and stone burden are necessary to assess the effectiveness of treatment and prevent recurrence 5, 7.