nephrolith

A nephrolith, more commonly referred to as a kidney stone or renal calculus, is a solid concretion formed in the kidney from crystallized minerals and organic matter. Stones may remain in the kidney without causing symptoms or migrate into the urinary tract, where they can provoke intense pain and obstruct urine flow.

Stones are varied in composition. The most common type is calcium-based, typically calcium oxalate or calcium phosphate. Other forms include uric acid stones, struvite stones (often linked to urinary tract infections), and cystine stones in people with certain hereditary disorders. Stone formation is influenced by factors such as urine volume, mineral saturation, pH, dehydration, obesity, and metabolic conditions.

Risk factors for nephrolithiasis include low fluid intake leading to concentrated urine, geographic and climatic influences, dietary patterns high in salt or oxalate, obesity, certain medications, and a family history of stones. Some conditions, such as gout or inflammatory bowel disease, can raise the risk of specific stone types.

Symptoms, when present, commonly include sudden, intense flank or groin pain, hematuria, nausea, vomiting, and sometimes fever if infection is present. Diagnosis typically relies on imaging, such as non-contrast computed tomography or ultrasound, along with urinalysis and relevant blood tests to assess function and metabolic risk.

Treatment depends on stone size and symptoms. Small stones may pass with pain relief and hydration. Larger stones or those causing infection or obstruction often require procedures such as extracorporeal shock wave lithotripsy, ureteroscopy, or percutaneous nephrolithotomy. Prevention focuses on adequate fluid intake, dietary modifications, and, when appropriate, medications to reduce stone-forming risk or correct metabolic abnormalities.