A stone that forms in the organs that produce and transport urine, including the kidneys, ureters (tubes connecting the kidneys and bladder), and the bladder. These stones form from crystalline materials normally present in the urine. They begin most often in the kidney and are commonly known as kidney stones; the rarer bladder calculi are called bladder stones and are found almost exclusively in men. Calculi can partially or completely block the passage of urine from the kidney affected, causing serious symptoms and side effects.
A kidney stone, also known as a urinary stone, is a solid mass that develops in the kidneys, ureters, or bladder. It forms when certain substances in the urine crystallize and combine together.
The majority of kidney and ureter stones consist of calcium oxalate or other salts that have crystallized from the urine. These stones can be associated with various factors, such as a diet abundant in oxalates (found in leafy vegetables and tea), elevated levels of calcium in the blood due to hyperparathyroidism (excessive activity of the parathyroid glands), or chronic dehydration.
Additional forms of kidney or ureteral stones can be linked to conditions such as gout and specific types of cancers. Stones that arise in these areas as a result of chronic urinary tract infections are referred to as “infective” stones. Moreover, kidney stones that occupy the entire network of urine-collecting ducts at the upper end of the ureter are known as “staghorn” calculi, owing to their characteristic shape.
Bladder stones commonly arise in developing countries due to dietary deficiencies. In contrast, in developed countries, they are predominantly caused by urine flow obstruction from the bladder and/or prolonged urinary tract infections. The composition of these stones is closely linked to the acidity or alkalinity of the urine.
The primary symptom of a kidney or ureteral stone is renal colic, which manifests as intense pain in the back, below the ribs, and often radiates to the groin. Nausea and vomiting may accompany this pain, and there might also be the presence of blood in the urine (hematuria). In the case of a bladder stone, difficulty in urination is typically experienced.
The investigation of a suspected calculus generally commences with a microscopic examination of the urine, which can uncover the presence of red blood cells and crystals. The urine’s acidity or alkalinity level may provide insights into the type of stone involved. Intravenous urography is typically employed to confirm the location of a stone within the urinary system. In some cases, particularly for stones containing calcium, a plain abdominal X-ray can visually detect the presence of stones.
Renal colic is typically managed through bed rest and the administration of analgesic medication (pain relievers). Adequate fluid intake is encouraged as it helps facilitate the passage of small stones in the urine without complications. For larger stones in the urinary tract, lithotripsy is often the initial treatment of choice. This procedure employs ultrasonic waves or shock waves to break down the stones. Alternatively, cystoscopy may be utilized to crush and remove stones located in the bladder and lower ureter. In certain cases, surgical intervention might be necessary to extract the stones.