What are the symptoms and treatment options for kidney stones?

Symptoms of Kidney Stones

Classic Presentation

Kidney stones typically present with severe, colicky flank pain (renal colic) that may radiate to the groin, accompanied by hematuria, urinary frequency, and dysuria. 1, 2

Primary Symptoms

• Renal colic: Severe, intermittent loin/flank pain that can be precipitated by dehydration, reduced urine output, increased protein intake, or heavy physical exercise 2
• Hematuria: Blood in urine, present in most symptomatic cases 2, 3
• Urinary symptoms: Frequent urination, dysuria (painful urination), and oliguria (reduced urine output) 2, 3
• Groin pain: Pain radiating from flank to groin area 3
• Fever: May indicate concurrent infection or obstruction, which constitutes a urological emergency 1, 4

Asymptomatic Presentation

• Incidental stones: Approximately 5% of individuals have asymptomatic stones discovered on abdominal imaging performed for other reasons 5
• Natural history: Among patients with asymptomatic stones followed with serial imaging, 11-32% develop symptoms or require procedures within 3-4 years 5

Emergency Warning Signs

Immediate medical attention is required if fever, signs of sepsis, or anuria (no urine output) occur with an obstructed kidney—this represents a urological emergency requiring urgent decompression. 1, 4

Red Flags Requiring Urgent Intervention

• Sepsis indicators: Fever, elevated inflammatory markers, leukocytosis, positive urine dipstick in the setting of obstruction 4
• Anuria: Complete absence of urine output with obstructed kidney 1, 4
• Solitary kidney: Any obstruction in patients with only one functioning kidney 4
• Acute kidney injury: Elevated serum creatinine, particularly critical in solitary kidney patients 4

Treatment Approach

Acute Pain Management

NSAIDs (diclofenac, ibuprofen, metamizole) are first-line treatment for renal colic, superior to opioids in reducing the need for additional analgesia. 1, 4

• Use the lowest effective NSAID dose due to cardiovascular and gastrointestinal risks 1, 4
• Reserve opioids (hydromorphine, pentazocine, tramadol) as second-line when NSAIDs are contraindicated or insufficient 1, 4
• Avoid pethidine due to high vomiting rates 4

Conservative Management

For stones amenable to conservative management, alpha-blockers provide the greatest benefit for distal ureteral stones >5mm. 1, 4

• Spontaneous passage rates: 75% for stones <5mm, 62% for stones ≥5mm, typically within 17 days 5
• Location matters: Distal ureteral stones pass in 68-83% of cases, mid-ureter 58-70%, upper ureter 49-52% 5
• Maximum conservative duration: 4-6 weeks from initial presentation; intervention indicated if stone doesn't pass within 28 days or symptoms worsen 4
• Uric acid stones: Oral chemolysis with alkalinization (citrate or sodium bicarbonate to pH 7.0-7.2) can dissolve stones and is strongly recommended 1, 4

Surgical Intervention

For stones >10mm in the distal ureter, ureteroscopy (URS) is first-line treatment; for stones >20mm regardless of location, percutaneous nephrolithotomy (PCNL) is preferred. 4

• Renal pelvic stones 1.6cm: Flexible ureteroscopy or PCNL are first-line options, with PCNL providing higher stone-free rates 6
• ESWL: Second-line option, less effective for stones >15mm 6
• Laser lithotripsy: Preferred method for stone fragmentation during flexible ureteroscopy, with complete stone removal as the goal 6

Prevention of Recurrence

All stone formers should maintain fluid intake achieving urine volume ≥2.5 liters daily—this is the single most critical component of stone prevention. 5, 1, 4

Dietary Modifications

• Sodium restriction: Limit to 2,300mg (100 mEq) daily for calcium stone formers 5
• Calcium intake: Consume 1,000-1,200mg of dietary calcium (not supplemental) to bind oxalate in the gut 5, 1
• Protein moderation: Limit animal protein intake, particularly for calcium and cystine stone formers 5

Pharmacological Prevention

For recurrent calcium stones with high urinary calcium, thiazide diuretics reduce recurrence risk by 48% (RR 0.52). 5

• Thiazide dosing: Hydrochlorothiazide 25mg twice daily or 50mg once daily, chlorthalidone 25mg once daily, or indapamide 2.5mg once daily 5
• Potassium citrate: For patients with low urinary citrate, reduces recurrence risk by 75% (RR 0.25) 5
• Allopurinol: For calcium oxalate stones with hyperuricosuria and normal urinary calcium, reduces recurrence risk by 41% (RR 0.59) 5

Metabolic Testing

Perform metabolic testing in all recurrent stone formers and high-risk first-time formers (age ≤25 years, bilateral disease, strong family history, solitary kidney). 5, 1, 4

• 24-hour urine collection: Analyze total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine 5, 1
• Stone analysis: Obtain at least once when stone is available to guide prevention strategies 5, 6, 1
• Serum testing: Creatinine, uric acid, ionized calcium, sodium, potassium, and intact parathyroid hormone if hyperparathyroidism suspected 5, 1

Common Pitfalls

• Delaying imaging in suspected sepsis: Never delay emergency care if clinical suspicion for sepsis or anuria is high—ultrasound should not delay urgent decompression 1
• Using opioids first-line: NSAIDs are superior to opioids for renal colic pain management 1, 4
• Calcium restriction: Paradoxically increases stone risk; maintain adequate dietary calcium intake 5, 1
• Inadequate fluid intake: Most critical modifiable risk factor; must achieve >2.5L urine output daily 5, 1, 4