Nephrolithiasis: Primary Symptoms and Treatment
Primary Symptoms
The classic presentation of nephrolithiasis is acute flank pain (renal colic) with or without hematuria, though stones may also be discovered incidentally on imaging. 1, 2
Pain Characteristics
- Sudden onset of severe, colicky flank pain that radiates anteriorly toward the groin, with location and radiation pattern depending on stone position in the urinary tract 1, 2, 3
- Pain intensity varies with individual pain threshold and degree of hydrostatic pressure changes above the obstruction 3
- Associated symptoms include nausea and vomiting in approximately 50% of cases, potentially leading to hypotension and syncope 3
- Pain may diminish over time as autoregulatory mechanisms activate to lower upper tract pressure 3
Other Presenting Features
- Hematuria (microscopic or gross) results from ureteral irritation and trauma 4
- Some patients remain asymptomatic, with stones detected incidentally on imaging performed for other indications 3
- Fever suggests concurrent infection and represents a urologic emergency 1, 2
Acute Pain Management
NSAIDs are first-line therapy for renal colic and should be administered immediately—specifically intramuscular diclofenac 75 mg, which provides superior pain relief within 30 minutes compared to opioids. 1, 2
First-Line Analgesic Approach
- Diclofenac 75 mg IM, ibuprofen, or metamizole are all acceptable NSAID options, with diclofenac having the strongest evidence 1, 2
- NSAIDs directly decrease ureteral smooth muscle tone and spasm, addressing the underlying pain mechanism rather than merely masking symptoms 2
- Use the lowest effective dose due to cardiovascular and gastrointestinal risks 1
Second-Line Analgesic Approach
- Opioids (hydromorphine, pentazocine, or tramadol—but NOT pethidine) should be reserved only when NSAIDs are contraindicated due to cardiovascular disease, gastrointestinal comorbidities, hypertension, renal insufficiency, heart failure, or peptic ulcer risk 1, 2
- Opioids carry dependence risks and are inferior to NSAIDs for stone pain 2
Emergency Situations Requiring Immediate Intervention
Urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory for sepsis and/or anuria in an obstructed kidney—this cannot wait. 1, 2
Criteria for Immediate Hospital Admission
- Shock or fever (suggests infected obstructed system) 2
- Failure to respond to analgesia within one hour 2
- Abrupt recurrence of severe pain after initial relief 2
- Patients over 60 years of age 2
- Women with delayed menses 2
Management of Infected Obstructed System
- Administer antibiotics immediately and adjust based on culture results 1
- Definitive stone treatment must be delayed until sepsis resolves 5
Conservative vs. Surgical Management
For stones ≤10 mm, offer observation with medical expulsive therapy using alpha-blockers (tamsulosin), which provides greatest benefit for stones >5 mm in the distal ureter. 1, 2
Conservative Management Protocol
- Alpha-blockers are strongly recommended for ureteral stones >5 mm in the distal ureter, achieving stone-free rates of 77.3% versus 54.4% for placebo 1, 2
- Maximum duration of conservative treatment is 4-6 weeks from initial presentation 2
- Instruct patients to drink fluids targeting urine output of at least 2.5 liters daily to promote stone passage 2
- Coffee, tea, wine, and orange juice are associated with lower stone risk, while sugar-sweetened beverages should be avoided 2
Surgical Intervention Indications
- For stones >10 mm, most will require surgical treatment, with ureteroscopy (URS) being first-line for distal ureteral stones 2
- URS has better stone-free rates with a single procedure but higher complication rates compared to shock wave lithotripsy 2
Initial Diagnostic Evaluation
Perform 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. 4, 2
History Components
- Query medical conditions, dietary habits, or medications that predispose to stone disease 4
- Assess average daily fluid intake (amount and specific beverages), protein types and amounts, calcium, sodium, high oxalate-containing foods, fruits and vegetables, and over-the-counter supplements 4
Laboratory Assessment
- Urinalysis should assess urine pH, indicators of infection, and identify crystals pathognomonic of stone type 4, 2
- Obtain urine culture if urinalysis suggests infection or in patients with recurrent UTIs 4, 5
- Serum chemistries identify underlying metabolic conditions associated with stone disease 4, 2
Imaging
- Renal ultrasonography is the recommended first-line imaging modality to quantify stone burden, with imaging within 7 days if stone has not passed 2
- Unenhanced CT may be used to evaluate for suspected asymptomatic nephrolithiasis as a cause of hematuria in the setting of negative ultrasound 4
Stone Analysis
- Obtain stone analysis at least once when available, as composition directs specific preventive measures 1, 2
- Obtain repeat stone analysis in patients not responding to treatment, as stone composition may change 1, 2
Long-Term Medical Management to Prevent Recurrence
If increased fluid intake fails to reduce stone formation, initiate pharmacologic monotherapy with a thiazide diuretic, citrate, or allopurinol based on stone type and metabolic abnormalities. 4, 1
Universal First-Line Preventive Measure
- Increase fluid intake spread throughout the day to achieve at least 2 liters of urine output daily 4, 1, 2
- This applies to all stone types and is the foundation of prevention 4, 1
Stone Type-Specific Pharmacologic Management
Calcium Oxalate/Phosphate Stones
- Maintain normal dietary calcium intake of 1,000-1,200 mg/day rather than restricting it 1, 2
- For hypercalciuria: thiazide diuretics (hydrochlorothiazide 50 mg, chlorthalidone 25-50 mg, or indapamide 2.5 mg) 4, 1, 2
- For hypocitraturia: potassium citrate 1, 2, 5
- For hyperuricosuria: allopurinol 4, 1, 2
- Note that higher doses of thiazides have better-established effectiveness but more adverse effects; lower doses may have fewer side effects but effectiveness is unknown 4
Uric Acid Stones
- Potassium citrate is first-line therapy to raise urine pH to 6.0-7.2, as most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor 1, 2
- Oral chemolysis with alkalinization (citrate or sodium bicarbonate to pH 7.0-7.2) can dissolve existing uric acid stones 1
- Allopurinol is NOT first-line for uric acid stones; urinary alkalinization is the correct initial therapy 2
Cystine Stones
- Stepwise approach: increased fluid intake, sodium and protein restriction, and urinary alkalinization with potassium citrate to achieve urine pH of 7.0 1, 2
- Add cystine-binding thiol drugs (tiopronin) if unresponsive to dietary modifications 2
Important Treatment Principles
- Monotherapy is as effective as combination therapy and should be preferred to minimize adverse effects 4, 1
- Although biochemical testing commonly guides treatment selection, randomized controlled trial evidence supporting this approach over empirical treatment is limited 4, 5
Follow-Up and Monitoring
Obtain 24-hour urine collection within 6 months of treatment initiation to assess response, measuring volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine. 1
Ongoing Monitoring Protocol
- Continue annual 24-hour urine collections to assess adherence and metabolic response 1
- Obtain periodic blood testing to assess for adverse effects in patients on pharmacologic therapy: hypokalemia and glucose intolerance (thiazides), elevated liver enzymes (allopurinol, tiopronin), anemia (acetohydroxamic acid, tiopronin), and hyperkalemia (potassium citrate) 1, 2
Common Pitfalls to Avoid
- Do not use opioids as first-line therapy—NSAIDs are superior and avoid dependence risks 1, 2
- Do not delay admission for fever with obstruction—this represents sepsis requiring urgent drainage 1, 2
- Do not prescribe allopurinol as first-line for uric acid stones—urinary alkalinization is the correct initial therapy 2
- Do not restrict dietary calcium—maintain normal intake of 1,000-1,200 mg/day 1, 2
- Do not recommend intensive hydration during acute renal colic—this is not currently recommended 3