CALCULUS. As used in medicine the term calculus (Lat. calculus, a pebble or small stone) is applied to certain concretions oc curring in the cavities or tissues of the body, usually as the result of the deposition of solids from some natural secretion. Calculi may be of many different sorts, and vary greatly in consistency, some being merely crumbly masses that can be crushed between the fingers, while others are extremely hard. Calculi occurring in the lachrymal or tear passages are called dacryoliths, while salivary calculi are formed in the salivary glands or their ducts, and amyg doliths in the tonsils. So-called rhinoliths are concretions which sometimes develop in the nasal cavities, usually as the result of the pres ence of some foreign body. The tartar on the teeth is sometimes spoken of as dental calculus. Pneumoliths occur in the lung and broncholiths in the bronchi; pancreatic calculi are found in the pancreas. The breast and prostate gland also occasionally harbor calcareous concretions, which in the former case are called lacteal cal culi. The deposits of chalk about the joints in gouty persons are sometimes referred to as arthritic calculi. Intestinal calculi or entero liths may give rise to serious disturbances, and if they happen to occur in the vermiform ap pendix often simulate date or other fruit stones in appearance. Before appendicitis was well understood their true nature often passed un recognized and when they were discovered in cases of the disease the malady was mistakenly attributed to the swallowing of such foreign bodies. The two most important types of cal culi, however, are the biliary calculi or gall stones, and urinary calculi.
Gall-stones are very common and fortunately usually do not give rise to symptoms. It is estimated that in Europe 10 per cent of the entire population have gall-stones, while in this country their frequency is held to be about 7 per cent. As their formation is probably en couraged by sedentary life and conditions favor ing stagnation of the bile, such as tight lacing, lack of exercise and constipation, they are three times commoner in women than in men. They rarely give symptoms in younger persons, and about half of the patients are over 40 years of age. Pregnancy is said to be of importance in favoring their formation. Biliary calculi may be extremely small or may attain con siderable size, stones as large as an English walnut not being at all uncommon. They also vary greatly in number and the smaller ones may be present in hundreds. They are com posed principally of cholesterin (q.v.), with varying but much smaller amounts of bile pig ment, lime and magnesium salts, fatty acids and bile acids. It is now generally assumed that an inflammatory or catarrhal condition of the mucous membrane of the gall-bladder (q.v.), usually induced by micro-organisms, furnishes the starting point of gall-stone forma tion. As already stated gall-stones may remain in the gall-bladder for years without causing symptoms, or their presence may be accom panied by inflammatory changes in the organ, or they may enter the gall-ducts and give rise to disturbances of various sorts, of which pain, local tenderness, persistent or remittent jaundice, clay-colored stools and chills and fever are conspicuous features. While a ra tional and hygienic mode of life will do much to prevent the formation of gall-stones, if they are present and give rise to symptoms that are at all severe surgical intervention is usually necessary to effect a cure.
Urinary calculi may be found either in the kidney, ureter or bladder, and are accordingly called renal, ureteral or vesical calculi. Kidney stones of small size often pass into the ureter and during, their journey downward to the blad der give rise to seizures of renal colic which in the agony and general prostration they cause are very similar to those of biliary colic. The pain is felt lower down in the abdomen and also in the back; frequently also radiating along the inner surface of the thigh. Aside from the attacks of colic renal stones may cause pain in the back, chills, fever and bloody or turbid urine containing pus. °Coral calculi)) are large stones which gradually fill the pelvis of the kidney, and in the conformation re produce with great fidelity the irregularities and recesses of this cavity. Very small concretions pass into the bladder without difficulty and are evacuated in the urine as Stone in the bladder is rare in women and in the male sex is seen of tenest in infancy and after the fiftieth year. The symptoms include pain in creased by jolting or bodily motion, frequent urination, pain at the end of urination — and sometimes sudden stoppage of the stream owing to the fact that the stone rolls into the neck of the bladder shutting off the flow — and usually bloody and turbid urine. Stone is especially common in old persons on account of the cystitis (q.v.) oftenpresent. Urinary cal culi may be composed of various materials, of which uric acid and urates, calcium oxalate (amulberry calculus"), calcium phosphate and ammonio-magnesium phosphate are the com monest, singly or in combination. Rarer forms are made up of calcium carbonate, cystin or xanthin. The cut section usually shows a laminated structure and a nucleus or starting point, which may be a blood clot, a shred of tissue, a bit of mucus, a small renal calculus, a mass of urates or a foreign body. Any condi tions encouraging excessive deposition of the urinary constituents predispose to urinary cal culi. Among such causes are lack of exercise, digestive disorders, defective oxidation, excesses in eating or drinking, catarrhal conditions of the urinary tract, etc. The tendency to stone formation is particularly pronounced in those what is called the gouty or lithemic diathesis. The diagnosis of renal calculi is facilitated by the use of the X-ray, while for the detection of bladder stones a special form of steel sound termed a astone searcher' is introduced into the bladder. The cystoscope is also of great service in this field. Individuals predisposed to stone should keep the urine abundant by the free use of water —preferably distilled—and milk, should take much open air, exercise and avoid the consumption of large amounts of meat, fats, sugar or alcohol. Green vegetables, salads, bread, poultry, fish, eggs and fruit should form the main articles of diet. Despite the claims of nostrum venders, when a stone is once formed there is little chance of its being dissolved by any plan of internal medi cation. If the condition causes decided symp toms surgical removal of the offending body is indicated. See LITHOTOMY ; LITHOTRITY.