Renal Calculus: A kidney stone, also known as a renal calculus, can be found in the kidney or lower in the urinary tract. The term "calculus" (plural: calculi) is derived from the Latin for pebble. These stones are a frequent cause of abdominal pain and discomfort, often affecting the back or groin. Statistically, one in twenty individuals will experience kidney stones at some point in their lives.The formation of these stones is linked to reduced urine output or elevated levels of stone-forming substances such as calcium, oxalate, uric acid, cystine, and phosphate. They develop in the kidney's urine-collecting areas and can vary in size from tiny specks to large, staghorn stones occupying the entire renal pelvis.The image shows cystine stones compared to a U.S. quarter, retrieved from the kidney of a young woman using percutaneous nephrolithotomy (PNL), a method for breaking and extracting dense stones common in cystinuria.Kidney stone pain typically begins suddenly, is extremely intense and intermittent, and does not ease with changes in position. It often radiates from the back to the flank and groin, and is frequently accompanied by nausea and vomiting. Contributing factors to stone formation include recent decreases in fluid intake, increased physical activity leading to dehydration, certain medications that elevate calcium levels, and past instances of stones.Treatment focuses on pain management, hydration, and antibiotics if a urinary infection is present. Most stones pass naturally within 48 hours, but some do not. Various factors affect the likelihood of passing a stone, such as body size, history of passing stones, pregnancy, and the stone's size. A stone measuring 4 mm has an 80% chance of passing, whereas a 5 mm stone has only a 20% chance. If a stone fails to pass, medical procedures, often performed by urologists, may be necessary.The formation of stones is known as nephrolithiasis or urolithiasis. "Nephrolithiasis" originates from the Greek words "nephros" (kidney) and "lithos" (stone), meaning kidney stone. "Urolithiasis" comes from the French "urine," itself derived from the Latin "urina" and Greek "ouron," meaning urine stone.
