View source for Calculus (medicine)



==Overview==
A '''calculus''' is a stone (a [[concretion]] of material, usually mineral salts) that forms in an organ or duct of the body.  Stones cause a number of important medical conditions.

==Common stone diseases==
A number of important medical conditions are caused by stones:
*[[Nephrolithiasis]] ([[kidney]] stones)
**Can cause [[hydronephrosis]] (swollen kidneys) and [[renal failure]]
**Can predispose to [[pyelonephritis]] (kidney infections)
**Can progress to [[bladder stone]]s and [[bladder outlet obstruction]]
*[[Cholelithiasis]] (gallstones)
**Can predispose to [[cholecystitis]] ([[gall bladder]] infections) and [[ascending cholangitis]] ([[biliary tree]] infection)
**Can progress to [[choledocholithiasis]] (gallstones in the bile duct) and [[gallstone pancreatitis]] (inflammation of the [[pancreas]])
*[[Rhinolith]] (nasal calculus)

Stones can also be asymptomatic.


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

==Aetiology==
* From an underlying abnormal excess of the mineral, eg. with elevated levels of [[calcium]] ([[hypercalcaemia]]) that may cause [[kidney stone]]s, dietary factors for [[gallstone]]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 gland|submandibular]] [[salivary gland]].
* [[Bezoar]]s are a type of calculus found in the [[intestine]]s of mostly [[ruminant]] [[animal]]s and may be composed of [[inorganic]] or [[Biological material|organic]] constituents.

==Pathophysiology & 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).

==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]] and [[CT scan]].
**Many stone types can be detected by [[Medical ultrasonography|ultrasound]].
*Factors contributing to stone formation (as in [[#Aetiology]]) are often tested:
**[[Medical laboratory|Laboratory]] 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 is sometimes needed.
*Infections due to stones have to be treated with antibiotics and/or surgery.
*Pain is managed with medication.

==See also==
*[[Rhinolith]] (nasal calculus)
*[[Salivary duct calculus]]
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