A calculus (plural calculi), often called a stone, is a concretion of material, usually mineral salts, that forms in an organ or duct of the body. Formation of calculi is known as lithiasis (/ˌlɪˈθaɪəsᵻs/). Stones can 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 gastroliths.
Calculi are usually asymptomatic, and large calculi may have required many years to grow to their large size.
In kidney stones, calcium oxalate is the most common mineral type (see Nephrolithiasis). Uric acid is the second most common mineral type, but an in vitro study showed uric acid stones and crystals can promote the formation of calcium oxalate stones.
Stones can cause disease by several mechanisms:
A number of important medical conditions are caused by stones:
Diagnostic workup varies by the stone type, but in general:
Modification of predisposing factors can sometimes slow or reverse stone formation. Treatment varies by stone type, but, in general:
The earliest operation for curing stones is given in the Sushruta Samhita (6th century BCE). The operation involved exposure and going up through the floor of the bladder.
The care of this disease was forbidden to the physicians that had taken the Hippocratic Oath because