Kidney Stones (Urolithiasis)

Kidney stones are hard mineral deposits that form inside the kidneys when urine becomes highly concentrated. They range from tiny grains to large staghorn stones. Most are calcium oxalate, but can also be uric acid, struvite, or cystine.

Calcium oxalate (70-80%), calcium phosphate, uric acid stones (linked to gout), struvite stones (from infections), and cystine stones (rare, genetic). Stone type determines the best treatment and prevention strategy.

Renal colic — severe flank pain radiating to the groin — is the hallmark symptom. Others include blood in urine, nausea, vomiting, frequent urination, and fever if infection is present. The pain often comes in waves.

Low-dose CT scan is the gold standard, detecting all stone types and sizes. Ultrasound is used for follow-up without radiation. KUB X-ray and urine analysis are also used. A 24-hour urine collection identifies metabolic causes.

Stones under 4 mm pass spontaneously in 80% of cases. Stones 4-6 mm pass in about 60% with medical expulsion therapy (alpha-blockers like tamsulosin). Stones over 6 mm usually need intervention. Drinking 2-3 litres daily helps.

Retrograde Intrarenal Surgery (RIRS) uses a flexible ureteroscope passed through the urethra to reach the kidney. A holmium or thulium laser pulverizes the stone to dust. No incisions needed. Ideal for stones up to 2 cm, often same-day discharge.

Percutaneous Nephrolithotomy (PCNL) is used for large stones (>2 cm) or staghorn calculi. A small puncture in the back accesses the kidney directly. Mini-PCNL and ultra-mini-PCNL use smaller tracks for less morbidity. Hospital stay is 1-2 days.

After RIRS: home same day or next morning, ureteral stent for 1-2 weeks (mild discomfort), full activity in 1 week. After PCNL: 1-2 days hospital, nephrostomy tube 1-2 days, normal activity in 2-3 weeks.

Drink 2.5-3 litres of water daily (urine should be pale yellow). Reduce salt and animal protein. For calcium oxalate: limit spinach and nuts. For uric acid stones: reduce purines and use allopurinol. Follow a metabolic evaluation-guided diet.

Without prevention, 50% of patients have a recurrence within 5 years and 80% within 10 years. With proper dietary and medical management, recurrence can be reduced by 50-80%. Annual kidney ultrasound and urine analysis guide long-term prevention.