What is the treatment approach for kidney stones?

Treatment Approach for Kidney Stones

The treatment of kidney stones should be tailored based on stone size, location, composition, and patient symptoms, with first-line therapy including increased fluid intake to achieve urine volume of at least 2.5 liters daily, dietary modifications, and appropriate medical therapy specific to stone type. 1

Initial Assessment and Management

• Obtain a detailed medical and dietary history to identify conditions, habits, or medications that may predispose to stone disease 1
• Order serum chemistries including electrolytes, calcium, creatinine, and uric acid to identify underlying medical conditions 1
• Perform urinalysis including dipstick and microscopic evaluation to assess urine pH, indicators of infection, and identify crystals pathognomonic of stone type 1
• Obtain urine culture if urinalysis suggests urinary tract infection or if patient has history of recurrent UTIs 1
• Imaging studies should be obtained to quantify stone burden and guide treatment decisions, with renal ultrasonography as the recommended first-line imaging modality 1, 2

Acute Pain Management

• NSAIDs are recommended as first-line treatment for acute kidney stone pain management due to superior efficacy, fewer side effects, and lower risk of dependence 3
• Opioids should be reserved as second-choice analgesics when NSAIDs are contraindicated or ineffective 3

Conservative Management vs. Intervention

• Conservative management is appropriate for uncomplicated ureteral stones up to 10 mm according to AUA guidelines and up to 6 mm according to EAU guidelines 4
• Medical expulsive therapy (MET) with alpha-blockers (tamsulosin) is recommended, particularly for stones >5 mm in the distal ureter 3
• The maximum duration of conservative treatment should be 4-6 weeks from initial clinical presentation 4
• For stones that fail to pass spontaneously, intervention is required based on stone size and location:

Ureteral Stones

• For distal ureteral stones >10 mm: Ureteroscopy (URS) is recommended as first-line treatment 4
• For distal ureteral stones <10 mm: URS is first option according to AUA/ES, while shock wave lithotripsy (SWL) is an equivalent option according to EAU 4
• For proximal ureteral stones: URS is recommended as first surgical modality regardless of stone size 4

Renal Stones

• For asymptomatic, non-obstructing caliceal stones: Active surveillance with follow-up imaging is appropriate for stones up to 15 mm 4
• For renal pelvis or upper/middle calyx stones <20 mm: Flexible ureteroscopy (fURS) and SWL are first-line treatments 4
• For stones >20 mm: Percutaneous nephrolithotomy (PCNL) is the first option regardless of location 4
• For lower pole stones <10 mm: fURS or SWL are primary treatments 4
• For lower pole stones 10-20 mm: fURS and PCNL are the suggested options 4

Medical Management Based on Stone Type

Calcium Stones

• Thiazide diuretics (hydrochlorothiazide 25 mg twice daily, chlorthalidone 25 mg daily, or indapamide 2.5 mg daily) should be offered to patients with high or relatively high urine calcium and recurrent calcium stones 4, 3
• Potassium citrate therapy should be offered to patients with recurrent calcium stones and low or relatively low urinary citrate 4, 3
• Allopurinol should be offered to patients with recurrent calcium oxalate stones who have hyperuricosuria and normal urinary calcium 3
• Counsel patients with calcium oxalate stones and relatively high urinary oxalate to limit intake of oxalate-rich foods while maintaining normal calcium consumption 4

Uric Acid Stones

• Potassium citrate is first-line therapy to raise urinary pH to approximately 6.0 4, 3
• Allopurinol should not be routinely offered as first-line therapy, as most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor 3

Cystine Stones

• First-line therapy includes increased fluid intake, restriction of sodium and protein intake, and urinary alkalinization 4, 3
• Counsel patients to limit sodium intake to 100 mEq (2,300 mg) or less daily 4
• Target urine volume is typically higher than for other stone formers, aiming to decrease urinary cystine concentration below 250 mg/L, often requiring oral intake of at least four liters per day 4
• Cystine-binding thiol drugs (tiopronin) should be offered to patients unresponsive to dietary modifications and urinary alkalinization, or those with large recurrent stone burdens 4, 3

Follow-up and Monitoring

• Obtain a single 24-hour urine specimen for stone risk factors within six months of initiating treatment to assess response to dietary and/or medical therapy 4
• After initial follow-up, obtain a single 24-hour urine specimen annually or with greater frequency, depending on stone activity 4
• Perform periodic blood testing to assess for adverse effects in patients on pharmacological therapy 4
• Obtain repeat stone analysis, when available, especially in patients not responding to treatment 4
• Monitor patients with struvite stones for reinfection 1

Common Pitfalls to Avoid

• Neglecting to address underlying metabolic abnormalities that contribute to stone formation 3
• Not considering the type of stone when determining appropriate medical therapy 3
• Prescribing allopurinol as first-line therapy for uric acid stones instead of urinary alkalinization with potassium citrate 3
• Using supplemental calcium rather than dietary calcium, as supplemental calcium may be associated with an increased risk of stone formation 4
• Failing to maintain adequate hydration, which is crucial for all stone types 5