What is the initial treatment approach for patients with kidney stones?

Initial Treatment of Kidney Stones

For acute kidney stone pain, administer intramuscular diclofenac 75 mg as first-line therapy, which should provide relief within 30 minutes, and is superior to opioids in efficacy while avoiding dependence risks. 1, 2

Acute Pain Management

NSAIDs are the definitive first-line analgesic for acute renal colic, not opioids. 1, 2

• Intramuscular diclofenac 75 mg is the preferred agent and route of administration 2
• Pain relief should occur within 30 minutes of administration 2
• NSAIDs work by decreasing ureteral smooth muscle tone and spasm, directly addressing the pain mechanism 2
• Oral and rectal routes are unreliable in acute settings and should be avoided 2

Reserve opioids (morphine sulfate with cyclizine) only when NSAIDs are contraindicated due to cardiovascular disease, gastrointestinal comorbidities, hypertension, renal insufficiency, heart failure, or peptic ulcer risk. 2

Immediate Assessment Requirements

All patients require medical assessment within 30 minutes to exclude life-threatening conditions and determine management setting. 2

Immediate hospital admission is mandatory for:

• Shock or fever (potential sepsis with obstruction—a urologic emergency) 2
• Failure to respond to analgesia within one hour 2
• Abrupt recurrence of severe pain after initial relief 2
• Patients over 60 years (consider leaking abdominal aortic aneurysm) 2
• Women with delayed menses (consider ectopic pregnancy) 2

Initial Diagnostic Workup

Obtain stone analysis at least once when available, as composition directs specific preventive measures. 3, 4

Perform urinalysis with both dipstick and microscopic evaluation to assess urine pH, infection indicators, and identify pathognomonic crystals. 3, 4

Order serum chemistries including electrolytes, calcium, creatinine, and uric acid to identify underlying conditions. 4

Obtain imaging within 7 days to quantify stone burden, with renal ultrasonography as the first-line modality. 4, 2, 5

Obtain urine culture if urinalysis suggests infection or patient has recurrent UTIs. 3, 4

Conservative Management vs. Intervention

For uncomplicated ureteral stones ≤10 mm, conservative management with medical expulsive therapy is appropriate if pain is well-controlled, sepsis is absent, and renal function is adequate. 4, 1

Prescribe alpha-blockers (tamsulosin) for medical expulsive therapy, particularly for stones >5 mm in the distal ureter. 4, 1

The maximum duration of conservative treatment is 4-6 weeks from initial presentation, with mandatory periodic imaging to monitor stone position and hydronephrosis. 4, 1, 2

For distal ureteral stones >10 mm, ureteroscopy is first-line surgical treatment. 3, 1

For distal stones <10 mm, both ureteroscopy and shock wave lithotripsy are acceptable, though ureteroscopy yields higher stone-free rates with slightly higher complication rates. 3, 1

Supportive Care for Home Management

Instruct patients to drink fluids targeting urine output of at least 2.5 liters daily to promote stone passage. 3, 2

Have patients void into a container or tea strainer to catch stones for analysis. 2

Follow up with telephone call one hour after initial assessment to verify pain control. 2

Stone Type-Specific Medical Management

Once stone composition is known, tailor long-term prevention:

For calcium stones:

• Offer thiazide diuretics to patients with high urinary calcium and recurrent stones 3, 4
• Offer potassium citrate to patients with low urinary citrate 3, 4

For uric acid stones:

• Potassium citrate is first-line therapy to alkalinize urine to pH ~6.0, NOT allopurinol 3, 4
• Most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor 3
• Oral chemolysis with alkalinization (target pH 7.0-7.2) has ~80% success rate 1

For cystine stones:

• First-line includes increased fluid intake, sodium/protein restriction, and urinary alkalinization 3, 4
• Add cystine-binding thiol drugs (tiopronin) if unresponsive to dietary modifications 3

Common Pitfalls to Avoid

Do not use opioids as first-line therapy—NSAIDs are superior and avoid dependence risks. 1, 2

Do not prescribe allopurinol as first-line for uric acid stones—urinary alkalinization with potassium citrate is correct. 3, 4

Do not delay admission for fever with obstruction—this represents sepsis requiring urgent drainage via percutaneous nephrostomy or ureteral stenting. 1

Do not routinely place stents before shock wave lithotripsy—it provides no benefit and causes stent-related symptoms. 1

Do not continue conservative management beyond 6 weeks without reassessment and consideration of intervention. 4, 1