Synonyms.—Renal Calculus; Renal Gravel.

Definition.—The presence in the kidney or in its pelvis of concretions formed by the precipitation of certain of the urinary solids, and varying in size from small sandy particles up to the capacity of the pelvis.

Varieties.—Renal concretions have been classified,—1. According to their size; thus, renal sand consists of fine pulverized crystals, renal gravel, a coarser deposit, which may contain particles as large as a pea; renal stones, or calculus, where the deposits exceed in size gravel or pea-sized concretions. 2. According to their chemical composition.

1. Uric-acid calculi occur most frequently. They vary in size, and are usually smooth, round, or oval in shape, and may have facets where they come into contact with each other. In color, they may be red, brown, black, or yellow. The breakage is crystalline, revealing a laminated formation of uric acid and ammonium urate. In children the calculus may be entirely uratic.

2. Calcium-oxalate concretions are not so common as the former. They are known as the "mulberry calculi," owing to their resemblance to the fruit of the mulberry, they being dark-brown, or black, oblong in shape, and covered with small nodules and points. They are extremely hard, and a broken surface reveals a radiate arrangement of deposits around a uric-acid nucleus. The smaller stones may be smooth.

3. Phosphatic calculi, while frequently found in the bladder, are but seldom found in the kidney. They are a combination of phosphate of lime, ammonia magnesium phosphate, and calcic carbonate. These always form in neutral or alkaline (ammoniacal) urine, and originate chiefly in the bladder. They are generally white or grayish in color, and are soft and easily broken. They may be either smooth or rough.

4. Renal calculi, composed of cystin, xanthin, indigo, carbonate of lime, urostealith, and urate of soda, are rare.

Cystin Calculi.—These are of a pale yellowish color and quite soft, generally rough, and in form are oval or cylindrical. While more common in the bladder, they may form in the kidney.

Xanthin.—These are the rarest of all the urinary calculi, and may consist entirely of xanthin, or there may be a mixture of uric acid and the urates. They may vary in color from white to pale yellow or brown, and vary in size from that of a pea to that of a hen's egg. They usually occur in children.

Indigo.—These are very rare. "Ord has reported a case in which an indigo calculus was found in the pelvis of the right kidney of a woman whose left kidney was destroyed by sarcoma. The stone weighed forty grams. Forbes has also reported a case of indigo calculus found in the pelvis and a calyx of one kidney. The stone weighed one hundred and forty-seven grams, was of a dark-brown color, and when drawn across paper left a blue mark." (Ogden.)

Urostealith, or fatty concretions, are very rare, and when fresh are quite soft, but become hard and brittle on drying. They are of a yellowish or brown color.

Urate of Soda.—These are light in color, not very hard, and rarely exceed the size of an average marble.

Carbonate of Lime.—While not uncommon in the herbivora, they are very rare in man. They are of a grayish color, small in size, spherical in form, and very hard.

Etiology.—There are certain predisposing causes, such as age, sex, geographical location, sedentary habits, and heredity.

Age.—Renal calculi arc quite common in children and in advanced life, and have been observed in the new-born.

Sex.—Men are more subject to nephrolithiasis than women, the shortness and dilatability of the urethra in the latter, no doubt, having its influence, as the bladder is the more readily flushed of irritating substances.

Geographical Location.—Renal calculi occur far more frequently in some countries and regions than in others, though the cause has never been made quite clear. Thus England and Holland are known as favorable to the formation of the calculi, and the character of the soil, drinking water, meteorological conditions, and habits of living may all enter as factors in the production of these various deposits.

Sedentary Habits.—Calculi are found more frequently in persons that lead an inactive life. It is very rare among soldiers, sailors, and those devoted to athletics.

Heredity.—There appears to be a tendency to calculi in some families, which would indicate heredity as an important factor.

The diet probably plays some part as a predisposing cause, and an excessive meat diet, the use of sour wine and alcohol, and water containing lime, favor their formation.

As to the precise causes that give rise to renal calculi, we have as yet no positive knowledge. "The precipitation of concretions from the urine is theoretically possible under two conditions; namely, either if the urine contains so much of any material that it can not retain all of it in solution, or if the reaction of the urine becomes so altered that certain substances are thrown out of solution. The simple precipitation from the urine of substances capable of forming calculi by no means, however, alone gives rise to the formation of renal calculi; for microscopic, and particularly microchemic, examination of renal calculi has shown that the calculus-forming substances have not simply crystallized together, but that they are bound together by an organic framework. This latter, probably, is scarcely other than the product of a catarrhal state of the mucous membrane of the renal pelvis, so that some clinicians have referred directly to a calculus-generating catarrh. Since, however, bacteria may play a causative role in the development of such a catarrh, one is forced to the conclusion that, as in the development of gall-stones, so also in the formation of renal calculi, bacteria are of great importance. In the case of calculus formation in decomposed urine, bacteria are again concerned, and they must be looked upon as the cause of the alkaline decomposition. In this way is explained the great influence that all conditions of urinary stasis exert upon the formation of renal calculi; for, whenever urinary stasis exists, excessive development of bacteria in the urine is possible." (Eichhorst.)

It will be seen that an important primary cause of calculus is the presence in the urine of some substance that acts as a nucleus about which the layers of crystals adhere. This substance may be mucus, blood-clots, epithelial particles, parasitic ova, tube-casts, or bacteria.

Pathology.—The changes that take place in the tissues depend upon the size, shape, and length of time present. Pyelitis very early follows, the character of the inflammation depending upon the mechanical irritation of the stone or stones. If the calculus be small and smooth, a simple or catarrhal inflammation of the mucous membrane is the result; but with a greater irritation there is likely to be a pyelonephritis or even pyonephrosis. There may be only a slight or a severe hemorrhage attending these processes. Ulcerative process may follow, revealing one or more calculi. Should the ureter become blocked, hydronephrosis is the common result. The calculus may occupy the entire pelvis, and project into the kidney. In rare cases, the calculus, by ulcerative processes, may perforate the ureter, the peritoneal cavity, the intestines, or the lung.

Cystitis, enlargement of the prostate gland, and urethral lesion are not uncommon.

Symptoms.—The symptoms embrace a wide range of phenomena, and depend upon the character and size of the calculi and their location, and may be divided into three classes: First, the passage of the calculus from the pelvis to the bladder; second, the retention of the calculus in the ureter; and, third, its retention in the pelvis of the kidney.

1. Passage of the Calculus from the Pelvis to the Bladder.—If the concretions be very small and smooth, the only symptom may be a long- time taken to void water, with an occasional sudden stoppage of flow, which is resumed again as a calculus pops out of the urethra. One patient, an old gentleman under my care, passed sixty concretions about the size of No. 9 bird-shot at a single micturition. They were smooth, and the only annoyance was the length of time consumed in voiding water. At other times, when the stones are large or rough, the pain is most agonizing, of a cutting or tearing sensation, beginning in the affected kidney, passing down along the ureter to the inner side of the thigh, and causing, in the male, a retraction of the testicle, due to the reflex action of the cremaster muscle. The pain is paroxysmal in character, though more or less continuous till it reaches the bladder. During its passage the patient writhes with the intense suffering, and in children a convulsion may ensue. The pulse is small and quick, a cold perspiration bathes the face, the patient is extremely anxious, and sometimes an attack terminates in syncope. In some cases there are chilly sensations, and the temperature may rise to 102° or 103°. Nausea and vomiting are quite common during an attack. There is an almost constant desire to micturate, attended by a burning sensation. The urine is generally scanty and often bloody in character. Occasionally the urine is copious, especially if the fellow kidney is in a normal condition. There may be but one stone present, or they may pass intermittently for years. An attack varies from a few hours to two or more days.

After a severe attack, there is often soreness in the loins and testicles for a day or two.

2. Retention of the Calculus Within the Ureter.—The attack begins as a renal colic; but after a time the excruciating pain subsides as the ureter becomes accustomed to the presence of the calculus, or a dull ache or soreness follows, which in time may entirely disappear. If the impaction does not completely occlude the ureter, or, if so, does it gradually, hydronephrosis will follow with its attendant symptoms; but if the obstruction be sudden and complete, the secretion of urine will-cease as soon as the pent-up urine equals the blood pressure in the renal artery. Atrophy of the kidney follows, degenerating into a cyst containing serum, pus, and calculous concretions.

If the fellow kidney be in good condition and able to do its work, no symptoms may develop to tell of the atrophy; but should the second kidney be unable to do its work, anuria with uremia follows, terminating in death.

3. Where the calculi remains in the pelvis of the kidney, a pyelitis occurs, varying from the simple to the suppurative form, depending largely upon the size of the concretions. In the milder forms the pain is of a dull, aching character, with tenderness over the affected organ. The urine is highly acid, of a dark, smoky color, and contains pus, blood, epithelial cells, and uric acid or lime salts.

Severe exertion may result in an attack of renal colic.

In the more severe form of pyelitis, the patient may be seized with a chill or rigor, high fever following, the patient rapidly becoming emaciated. Hectic fever and night-sweats follow, with all the evidence of pronounced sepsis. The urine is scanty, high-colored, and contains pus and blood. If both kidneys are involved, the patient dies of uremia. The general health of many of these patients is but little disturbed.

Diagnosis.—The characteristic pain extending downwards along the ureters and inner thigh, with retraction of the testicles in the male, and pain in the labium in the female, the small, frequent pulse, the cold perspiration, the almost constant desire to micturate, the pain in voiding water, and the scanty, bloody urine, are symptoms that can hardly be mistaken for any other lesion. Where these symptoms are not so pronounced as when the calculus is retained in the pelvis of the kidney, an examination by the X-ray will reveal the presence of the stone.

Prognosis.—Where the calculi are small enough to pass into the bladder, the prognosis is favorable, though the disease has a tendency to recur. Where the calculi remain in the pelvis of the kidney the prognosis is always unfavorable, atrophy of the kidney or pyelitis in various forms resulting. Also where the calculus remains fixed in the ureter, the prognosis is unfavorable.

Treatment.—The first object is to give relief to the agonizing pain, which may be accomplished by the hot bath or the use of hot packs or poultices. A hypodermic injection of morphia, one-quarter grain, at the beginning of an attack, assisted by the inhalation of chloroform till the patient becomes easy, will be the means for bringing the quickest relief.

In the intervals between the attacks, the treatment will be directed to keeping the urine abundant, and, if excessively acid, to render it alkaline. The free use of aralia, epigea, chimaphila, eupatorium, and althea will yield good results. These agents will respond more promptly, however, as infusions than when given as specific tinctures. The patient is instructed to drink freely of the infusion, which not only increases the flow of urine, but diminishes its acidity. The tincture of eryngium, gelsemium, and apis, when specifically indicated, will not disappoint any one in their action. The free use of plain distilled wearer, or water rendered alkaline by adding the salts of potassium, the acetate, citrate, or bicarbonate, is to be commended, also lithiated waters.

Piperazin in five-grain doses, three or four times a day, has proved beneficial in some cases, and deserves a place in the treatment of renal calculi, though the exaggerated claims made as to its power as a solvent to uric-acid stones should not be taken too seriously.

Van Noorden and Straus recommend ten to fifteen grains of calcium carbonate, three times a day, as a uric-acid solvent. A number of favorable reports has attended this treatment.

The diet should consist largely of fruits and vegetables; but little meat should be eaten, avoiding especially red meats, liver, and sweet-breads. Starchy food and sweets should be taken in very limited quantities. The patient should live much in the open air, and take regular and systematic exercise. Where the calculus obstructs the ureters, or sets up destructive changes in the pelvis, with septic poisoning, the patient should be turned over to the hands of the surgeon, operative measures giving the only promise of relief.

The Eclectic Practice of Medicine, 1907, was written by Rolla L. Thomas, M. S., M. D.