What are the current guidelines for evaluating, managing, and preventing kidney stones in adult patients?

Kidney Stone Management Guidelines

Initial Diagnostic Evaluation

All patients newly diagnosed with kidney or ureteral stones require a screening evaluation consisting of detailed medical and dietary history, serum chemistries (electrolytes, calcium, creatinine, uric acid), and urinalysis with both dipstick and microscopic examination. 1, 2

Serum Testing

• Obtain electrolytes, calcium, creatinine, and uric acid to identify underlying metabolic conditions associated with stone disease 1, 2
• Check serum intact parathyroid hormone (PTH) if primary hyperparathyroidism is suspected (elevated or high-normal serum calcium) 2
• Order CBC and platelet count if symptoms suggest anemia, thrombocytopenia, or infection 2

Urinalysis and Culture

• Perform urinalysis with dipstick and microscopic evaluation to assess urine pH, detect infection indicators, and identify pathognomonic crystals 1, 2
• Obtain urine culture if urinalysis suggests urinary tract infection or if the patient has recurrent UTIs 1, 2

Imaging

• Non-contrast CT scan of the abdomen and pelvis is the gold standard for confirming stone location, size, and degree of obstruction 3, 4
• Renal ultrasonography is the recommended first-line imaging modality and is preferred in pregnant patients 5, 4
• Review or obtain imaging to quantify stone burden, as multiple or bilateral renal calculi indicate higher recurrence risk 2

Stone Analysis

• Obtain stone composition analysis at least once when a stone is available, as composition (calcium oxalate, calcium phosphate, uric acid, cystine, or struvite) fundamentally directs preventive measures. 2, 3

Critical History Components

• Query about medical conditions (obesity, metabolic syndrome, diabetes, hypertension, gout, intestinal malabsorption, anatomical abnormalities), dietary habits, and medications that predispose to stone disease 1, 2, 5
• Identify stone-provoking medications or supplements the patient regularly uses 1, 2
• Assess family history of stones, previous stone episodes, and renal anatomic abnormalities 2, 5

Dietary History Specifics

• Document average daily fluid intake (amount and specific beverages consumed) 1, 2
• Assess protein intake (types and amounts), particularly animal-derived purines 1, 2
• Evaluate calcium intake, sodium intake, and high oxalate-containing food consumption 1, 2
• Review fruits, vegetables, and over-the-counter supplement consumption 1, 2

Acute Pain Management

NSAIDs (diclofenac, ibuprofen, or ketorolac) are first-line treatment for acute kidney stone pain, superior to opioids due to better efficacy, fewer side effects, and lower dependence risk. 2, 3, 5, 6

• Reserve opioids (hydromorphone or tramadol) as second-line analgesics only when NSAIDs are contraindicated or insufficient 2, 3

Medical Expulsive Therapy

• Alpha-blockers (tamsulosin) are recommended for stones >5 mm in the distal ureter to facilitate passage. 2
• Medical expulsive therapy is considered first-line for patients with uncomplicated distal ureteral stones ≤10 mm in diameter 5

Metabolic Testing: Who Needs 24-Hour Urine Collection

Perform additional metabolic testing (24-hour urine collection) in the following patients: 2

• Recurrent stone formers
• First-time stone formers who are high-risk or interested in prevention
• Patients with multiple or bilateral renal calculi at presentation
• Presence of nephrocalcinosis suggesting underlying metabolic disorder

24-Hour Urine Collection Parameters

• Obtain one or two 24-hour urine collections (two preferred) analyzed for total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine (minimum) 2, 3
• Add urinary cystine measurement if cystine stones are known, family history of cystinuria exists, or cystinuria is suspected 2
• Suspect primary hyperoxaluria when urinary oxalate exceeds 75 mg/day in adults without bowel dysfunction 2

Prevention: Dietary Modifications

Increase fluid intake to achieve at least 2.5 liters of urine output daily—this is the most critical component of stone prevention and reduces recurrence by approximately 50%. 2, 7, 3, 6

Specific Dietary Recommendations for Calcium Oxalate Stone Formers

• Maintain normal dietary calcium intake of 1,000-1,200 mg/day (restricting calcium paradoxically increases oxalate absorption and stone risk) 7, 3
• Restrict dietary sodium to ≤2,300 mg/day 7
• Reduce animal protein to 5-7 servings of meat, fish, or poultry per week 7
• Increase fruits and vegetables to counterbalance acid load and raise urinary pH 7

Beverage Recommendations

• Encourage water, coffee, tea, beer, and wine consumption, as they reduce stone formation risk 7
• Avoid grapefruit juice (increases stone risk by 40%), sugar-sweetened beverages, and colas acidified with phosphoric acid 7

Prevention: Pharmacologic Therapy

The treatment hierarchy prioritizes potassium citrate as first-line pharmacologic therapy when dietary measures fail. 7

Potassium Citrate

• Dose: 30-100 mEq/day for patients with low urinary citrate (<320 mg/day) 7
• Target urinary pH: 6.0-6.5 (should not exceed 7.0 to avoid calcium phosphate precipitation) 7

Thiazide Diuretics

• Recommended for hypercalciuria (>200 mg/day) 7
• Options: hydrochlorothiazide 50 mg daily, chlorthalidone 25-50 mg daily, or indapamide 2.5 mg daily 3

Allopurinol

• Recommended for hyperuricosuria (>800 mg/day in men, >750 mg/day in women) with normocalciuria 7, 3

Monitoring and Follow-Up

Repeat 24-hour urine collection at 6 months after initiating therapy to assess urinary pH, citrate (target >320 mg/day), calcium, uric acid, oxalate levels, and adequate urine volume (>2 liters/day). 7, 3

• Monitor urinary pH to ensure it does not exceed 7.0 7
• Monitor stone recurrence with imaging as clinically indicated 7

Indications for Active Stone Removal

Asymptomatic kidney stones should be removed in case of: 6

• Stone growth on serial imaging
• Development of symptoms
• Urinary obstruction
• Recurrent infections
• Lack of access to health care

Conditions requiring immediate referral or urgent intervention: 6

• Urinary infection with obstruction (requires urgent drainage) 2
• Stone larger than 10 mm 6
• Significant hydronephrosis 6

Common Pitfalls to Avoid

• Do not skip stone analysis when available—composition fundamentally changes prevention strategy (uric acid, cystine, and struvite stones require completely different management approaches than calcium stones) 2, 3
• Do not delay urine culture if infection is suspected—infected obstructing stones require urgent drainage 2
• Do not order 24-hour urine collection immediately in all first-time stone formers—reserve for high-risk patients or those with recurrent stones 2
• Do not recommend "eight glasses of water per day"—instead tailor recommendations using 24-hour urine volume data 7
• Do not restrict dietary calcium—this paradoxically increases stone risk by increasing oxalate absorption 7, 3