A calculus (: 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. 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, which are ingested rather than grown endogenously.

Types

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

Cause

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.

Pathophysiology

Stones can cause disease by several mechanisms: A number of important medical conditions are caused by stones:

Diagnosis

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

Treatment

Modification of predisposing factors can sometimes slow or reverse stone formation. Treatment varies by stone type, but, in general:

History

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:

Etymology

The word comes from Latin calculus "small stone", from calx "limestone, lime", probably related to Greek χάλιξ chalix "small stone, pebble, rubble", which many trace to a Proto-Indo-European language root for "split, break up". Calculus was a term used for various kinds of stones. In the 18th century it came to be used for accidental or incidental mineral buildups in human and animal bodies, like kidney stones and minerals on teeth.