What is the initial management for patients with renal stones?

Initial Management of Renal Stones

Administer intramuscular diclofenac 75 mg as first-line therapy for acute kidney stone pain, which provides relief within 30 minutes and is superior to opioids. 1

Acute Pain Control

• NSAIDs are the definitive first-line analgesic for acute renal colic, not opioids, because they decrease ureteral smooth muscle tone and spasm, directly addressing the pain mechanism. 1
• Reserve opioids (such as morphine sulfate with cyclizine) only when NSAIDs are contraindicated due to cardiovascular disease, gastrointestinal comorbidities, hypertension, renal insufficiency, heart failure, or peptic ulcer risk. 1
• A common pitfall is using opioids as first-line therapy—this should be avoided as NSAIDs are superior and eliminate dependence risks. 1

Immediate Assessment and Triage

• All patients require medical assessment within 30 minutes to exclude life-threatening conditions and determine whether outpatient or inpatient management is appropriate. 1
• Immediate hospital admission is mandatory for: 1
  • Shock or fever (suggests sepsis with obstruction requiring urgent drainage)
  • Failure to respond to analgesia within one hour
  • Abrupt recurrence of severe pain after initial relief
  • Patients over 60 years
  • Women with delayed menses
• Do not delay admission for fever with obstruction—this represents sepsis requiring urgent drainage via percutaneous nephrostomy or ureteral stenting. 1

Initial Diagnostic Workup

Laboratory Testing

• Perform urinalysis with both dipstick and microscopic evaluation to assess urine pH, infection indicators, and identify pathognomonic crystals. 1, 2
• Order serum chemistries including electrolytes, calcium, creatinine, and uric acid to identify underlying conditions. 1, 2
• Obtain urine culture if urinalysis suggests urinary tract infection or if the patient has a history of recurrent UTIs. 2

Imaging

• Obtain imaging within 7 days to quantify stone burden, with renal ultrasonography as the first-line modality. 1, 3
• Imaging guides treatment decisions by documenting stone size, location, and degree of obstruction. 2

Stone Analysis

• Obtain stone analysis at least once when available, as composition directs specific preventive measures. 1, 4, 2
• Instruct patients to void into a container or tea strainer to catch stones for analysis. 1

Conservative Management Algorithm

Criteria for Outpatient Management

For uncomplicated ureteral stones ≤10 mm, conservative management with medical expulsive therapy is appropriate if: 1

• Pain is well-controlled
• Sepsis is absent
• Renal function is adequate

Medical Expulsive Therapy

• Prescribe alpha-blockers, such as tamsulosin, for medical expulsive therapy, particularly for stones >5 mm in the distal ureter. 1, 3
• The maximum duration of conservative treatment is 4-6 weeks from initial presentation, with mandatory periodic imaging to monitor stone position and hydronephrosis. 1

Supportive Care Instructions

• Instruct patients to drink fluids targeting urine output of at least 2.5 liters daily to promote stone passage. 1, 4, 2
• Provide complete pain relief and encourage diuresis. 5

Stone Type-Specific Pharmacological Management

Calcium Stones

• Offer thiazide diuretics to patients with high urinary calcium and recurrent stones, combined with dietary sodium restriction to maximize hypocalciuric effect. 1, 4
• Prescribe potassium citrate to patients with low urinary citrate (hypocitraturia). 1, 4
• Maintain normal dietary calcium intake of 1,000-1,200 mg per day and limit sodium intake to 2,300 mg daily. 4

Uric Acid Stones

• Potassium citrate is first-line therapy to alkalinize urine to pH ~6.0, as most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor. 1, 4
• Do not prescribe allopurinol as first-line for uric acid stones—urinary alkalinization with potassium citrate is correct. 1
• Allopurinol is reserved for patients with hyperuricosuria (>800 mg/day) and normal urinary calcium. 4

Cystine Stones

• First-line includes increased fluid intake targeting at least 4 liters per day, sodium/protein restriction, and urinary alkalinization. 1, 4
• Add cystine-binding thiol drugs, such as tiopronin, if unresponsive to dietary modifications. 1

Struvite Stones

• Acetohydroxamic acid (AHA) may be considered as a urease inhibitor in patients at high risk for recurrence or when surgery is not feasible, though extensive side effects may limit use. 4
• Monitor for reinfection. 2

Follow-up and Metabolic Testing

• Perform metabolic testing with 24-hour urine collections in high-risk or interested first-time stone formers and all recurrent stone formers. 4
• Analyze 24-hour urine for total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine. 4
• Obtain 24-hour urine specimen within six months of initiating treatment to assess response to therapy. 4
• Monitor for adverse effects in patients on pharmacological therapy, such as hypokalemia with thiazides and hyperkalemia with potassium citrate. 4
• Schedule follow-up with urology or nephrology for comprehensive stone management. 2