A calculus is a stone (a concretion

Concretion

A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity . Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin con meaning 'together' and crescere meaning 'to grow'...

 of material, usually mineral salts) that forms in an organ or duct of the body. Formation of calculi is known as lithiasis. Stones cause a number of medical conditions.

Some common principles (below) apply to stones at any location, but for specifics see the particular stone type in question.

Calculi are not to be confused with gastrolith

Gastrolith

A gastrolith, also called a stomach stone or gizzard stones, is a rock held inside a gastrointestinal tract. Gastroliths are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. The grain size depends upon the size of the animal and the gastrolith's...

s.

Types of lithiasis

• Calculi in the renal system (kidneys, ureters, urinary bladder, urethra) can be of any one of several compositions, including mixed. Principal compositions include oxalate
  Oxalate
  Oxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...
  
   and urate.
• Calculi in the nasal passages (rhinolith
  Rhinolith
  A rhinolith is a calculus present in the nasal cavity. The word is derived from the roots rhino- and -lith, literally meaning "nose stone". It is an uncommon medical phenomenon, not to be confused with dried nasal mucus. Rhinoliths can cause nasal obstruction, epistaxis, headache, sinusitis and...
  
  s) are rare.
• Calculi in the gastrointestinal tract (enterolith
  Enterolith
  An enterolith is a mineral concretion or calculus formed anywhere in the gastrointestinal system. Enteroliths are uncommon and usually incidental findings but, once found, they require at a minimum watchful waiting...
  
  s) can be enormous. Individual enteroliths weighting many pounds have been reported in horses.
• Salivary duct calculus
• Tonsillolith
  Tonsillolith
  Tonsilloliths, also known as a tonsil stones, are clusters of calcified material that form in the crevices of the tonsils. While they occur most commonly in the palatine tonsils, they may also occur in the lingual tonsils. Tonsilloliths have been recorded weighing from 300 mg to 42 g...
  
  

Calculi usually are asymptomatic, and large calculi may have required many years to grow to their large size.

Etiology

• From an underlying abnormal excess of the mineral, eg. with elevated levels of calcium
  Calcium
  Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
  
   (hypercalcaemia
  Hypercalcaemia
  Hypercalcaemia is an elevated calcium level in the blood. . It can be an asymptomatic laboratory finding, but because an elevated calcium level is often indicative of other diseases, a workup should be undertaken if it persists...
  
  ) that may cause kidney stone
  Kidney stone
  A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine...
  
  s, dietary factors for gallstone
  Gallstone
  A gallstone is a crystalline concretion formed within the gallbladder by accretion of bile components. These calculi are formed in the gallbladder, but may pass distally into other parts of the biliary tract such as the cystic duct, common bile duct, pancreatic duct, or the ampulla of...
  
  s.
• Local conditions at the site in question that promote their formation, e.g. local bacteria action (in kidney stones) or slower fluid flow rates, a possible explanation of the majority of salivary duct calculus occurring in the submandibular
  Submandibular gland
  The paired submandibular glands are salivary glands located beneath the floor of the mouth. In humans, they account for 70% of the salivary volume and weigh about 15 grams. Unstimulated in humans, the percentage contribution to whole saliva; ~25% Parotid, Submandibular and Sublingual ~ 67% and...
  
   salivary gland
  Salivary gland
  The salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...
  
  .
• Enterolith
  Enterolith
  An enterolith is a mineral concretion or calculus formed anywhere in the gastrointestinal system. Enteroliths are uncommon and usually incidental findings but, once found, they require at a minimum watchful waiting...
  
  s are a type of calculus found in the intestine
  Intestine
  In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
  
  s of animal
  Animal
  Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
  
  s (mostly ruminant
  Ruminant
  A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...
  
  s) and human
  Human
  Humans are the only living species in the Homo genus...
  
  s, and may be composed of inorganic or organic
  Biological material
  Biological material may refer to:* Tissue , or just tissue* Biomass, living or dead biological matter, often plants grown as fuel* Biomass , the total mass of living biological matter* Biomaterials...
  
   constituents.
• Bezoar
  Bezoar
  A bezoar is a mass found trapped in the gastrointestinal system , though it can occur in other locations. A pseudobezoar is an indigestible object introduced intentionally into the digestive system....
  
  s are lumps of indigestible material in the stomach
  Stomach
  The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
  
   and/or intestines; most commonly, they consist of hair (in which case they are also known as hairball
  Hairball
  A hairball is a small collection of hair or fur formed in the stomach of animals that is occasionally vomited up when it becomes too big. Hairballs are primarily a tight elongated cylinder of packed fur, but may include bits of other elements such as swallowed food. Cats are especially prone to...
  
  s). A bezoar may form the nidus of an enterolith.

In kidney stones, calcium oxalate

Calcium oxalate

Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...

 is the most common mineral type (see Nephrolithiasis). Uric acid is the second most common mineral type, but an in vitro

In vitro

In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...

 study shows that uric acid stones and crystals can promote the formation of calcium oxalate

Calcium oxalate

Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...

 stones.

Pathophysiology and symptoms

Stones can cause disease by several mechanisms:

• Irritation of nearby tissues, causing pain, swelling, and inflammation.
• Obstruction of an opening or duct, interfering with normal flow and disrupting the function of the organ in question.
• Predisposition to infection (often due to disruption of normal flow).

A number of important medical conditions are caused by stones:

• Nephrolithiasis (kidney
  Kidney
  The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
  
   stones)
  • Can cause hydronephrosis
    Hydronephrosis
    Hydronephrosis is distension and dilation of the renal pelvis calyces, usually caused by obstruction of the free flow of urine from the kidney, leading to progressive atrophy of the kidney...
    
     (swollen kidneys) and renal failure
    Renal failure
    Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
    
    
  • Can predispose to pyelonephritis
    Pyelonephritis
    Pyelonephritis is an ascending urinary tract infection that has reached the pyelum or pelvis of the kidney. It is a form of nephritis that is also referred to as pyelitis...
    
     (kidney infections)
  • Can progress to urolithiasis
    Urolithiasis
    A bladder stone is a solid concretion or crystal aggregation found in the urinary bladder...
    
    
• Urolithiasis
  Urolithiasis
  A bladder stone is a solid concretion or crystal aggregation found in the urinary bladder...
  
   (urinary bladder
  Urinary bladder
  The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...
  
   stones)
  • Can progress to bladder outlet obstruction
    Bladder Outlet Obstruction
    Bladder Outlet Obstruction is a urological condition where the urine flow from the urinary bladder through the urethra is impeded ....
    
    
• Cholelithiasis (gallstones)
  • Can predispose to cholecystitis
    Cholecystitis
    -Signs and symptoms:Cholecystitis usually presents as a pain in the right upper quadrant. This is known as biliary colic. This is initially intermittent, but later usually presents as a constant, severe pain. During the initial stages, the pain may be felt in an area totally separate from the site...
    
     (gall bladder infections) and ascending cholangitis
    Ascending cholangitis
    Ascending cholangitis or acute cholangitis is an infection of the bile duct , usually caused by bacteria ascending from its junction with the duodenum...
    
     (biliary tree
    Biliary tree
    The biliary tract is the common anatomical term for the path by which bile is secreted by the liver then transported to the first part of the small intestine, also known as the duodenum...
    
     infection)
  • Can progress to choledocholithiasis (gallstones in the bile duct) and gallstone pancreatitis (inflammation of the pancreas
    Pancreas
    The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist...
    
    )
• Gastric calculi can cause colic, obstruction, torsion, and necrosis.

Diagnosis

Diagnostic workup varies by the stone type, but in general:

• Clinical history and physical examination can be sufficient in some cases.
• Imaging studies are often needed.
  • Some stone types (mainly those with substantial calcium content) can be detected on X-ray
    X-ray
    X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
    
     and CT scan.
  • Many stone types can be detected by ultrasound
    Medical ultrasonography
    Diagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions...
    
    .
• Factors contributing to stone formation (as in #Etiology) are often tested:
  • Laboratory
    Medical laboratory
    A medical laboratory or clinical laboratory is a laboratory where tests are done on clinical specimens in order to get information about the health of a patient as pertaining to the diagnosis, treatment, and prevention of disease.-Departments:...
    
     testing can give levels of relevant substances in blood or urine.
  • Some stones can be directly recovered (at surgery, or when they leave the body spontaneously) and sent to a laboratory for analysis of content.

Treatment

Again, treatment varies by stone type, but in general:

• Modification of predisposing factors can sometimes slow or reverse stone formation.
  • Medications can sometimes be used.
  • Surgery (lithotomy
    Lithotomy
    Lithotomy from Greek for "lithos" and "tomos" , is a surgical method for removal of calculi, stones formed inside certain hollow organs, such as the kidneys , bladder , and gallbladder , that cannot exit naturally through the urinary system or biliary tract...
    
    ) is sometimes needed.
• Infections due to stones have to be treated with antibiotics and/or surgery.
• Pain is managed with medication.
• Calculi may be removed by a method known as electro sound waves lithotripsy (ESWL).

History

The earliest operation for curing stones is also given in the Sushruta Samhita

Sushruta Samhita

The Sushruta Samhita is a Sanskrit text, attributed to one Sushruta, foundational to Ayurvedic medicine , with innovative chapters on surgery....

(6th century BCE). The operation involved exposure and going up through the floor of the bladder.

External links

• CancerWeb (UK): Lithiasis