Kidney stones — medically known as nephrolithiasis or urolithiasis — form when minerals and salts crystallise in the kidneys. The most common type, calcium oxalate stones, accounts for nearly 80% of cases. Contributing factors include chronic dehydration, high-sodium or high-protein diets, metabolic conditions such as hyperparathyroidism, and a family history of stone disease.
The cardinal symptom is renal colic: a severe, cramping pain that begins in the flank and radiates to the groin. This occurs as the stone moves through the ureter. Associated symptoms include nausea, vomiting, blood in the urine (haematuria), and an urgency to urinate. Small stones — under 5mm — typically pass spontaneously with adequate hydration and analgesics. Stones between 5–10mm may require medical expulsive therapy or urological intervention.
For stones that do not pass, modern urological surgery offers several options. Retrograde Intrarenal Surgery (RIRS) involves passing a flexible ureteroscope through the natural urinary tract to reach and fragment the stone with a holmium laser. It requires no incisions and allows same-day discharge. Percutaneous Nephrolithotomy (PCNL) is preferred for large or complex stones, and involves creating a small tract directly into the kidney. Shockwave lithotripsy (SWL) is a non-invasive option for select stones in the upper urinary tract.
Prevention is the most underestimated aspect of stone disease management. After a first stone event, 50% of patients will have a recurrence within 5 years without metabolic evaluation and dietary guidance. Key preventive measures include maintaining a urine output of at least 2 litres per day, reducing sodium intake, moderating animal protein, and — contrary to popular belief — maintaining adequate dietary calcium rather than restricting it. A 24-hour urine metabolic panel guides personalised prevention in recurrent stone formers.