Causes

Nephritis may be produced experimentally by swallowing, inhaling, or otherwise introducing into the blood certain chemicals, such as salts of arsenic, lead, chromium and turpentine and some other oils that are renal irritants and that must be eliminated by the kidneys. Cases of Bright's disease of this origin are rare. Nephritis is, as a rule, due to other causes; chiefly to infection and the elimination of toxins by the kidneys. Sometimes the microbes causing an infectious disease are themselves the direct cause of nephritis; more frequently they are a cause, but not the only one, for toxins generated by abnormal fermentation within the gastrointestinal tract are among the most important provocatives of this lesion. If digestion has been undisturbed and defecation perfect prior to the onset of diphtheria, scarlet fever, and similar diseases, and if the stomach is not overloaded after the disorder starts, and the intestines are regularly and thoroughly emptied, nephritis is of rare occurrence. The importance of the condition of the alimentary organs in the production of nephritis in scarlet fever is emphasized by the observations of Jaccoud, who found that a milk diet maintained during an attack of scarlet fever, and for two or three weeks after, was a very certain preventive of renal complications.

Those infections that are almost always accompanied by nephritis, such as yellow fever and cholera, are diseases in which pre-eminently the contents of the gastrointestinal tract are in a state of abnormal and excessive fermentation. In those diseases the infectious agent is undoubtedly the cause of the alimentary disorder. The nephritis is chiefly, if not wholly, due to the toxins that it produces in the intestines. Microorganisms, however, sometimes play a part in causing the renal inflammation. They are often eliminated, both dead and alive, in the urine; but the number found in it does not always bear relation to the degree of irritation of the kidneys, when any exists. Numerous colon bacilli and typhoid bacilli have been found in urine that does not contain albumin or other evidence of structural disease of the kidneys. Structural diseases of these organs, however, producing albuminuria and renal tube-casts, are common in typhoid fever, but are evidently not due solely or chiefly to contact of the bacilli with the kidneys.

Exposure to cold and wet is frequently named as a cause of acute nephritis. Good clinicians, however, have doubted the accuracy of this view. The rheumatoid diseases are undoubtedly produced by such exposure, in the presence, that is, of a peculiar state of the blood or of nutrition, but rarely are complicated by nephritis. It is also quite conceivable that acute nephritis may be caused by cold, providing the blood is filled with irritating toxins. However, it is evident, at all events, that the prevention of fermentation within the alimentary tract is of the utmost importance if nephritis is to be averted.

Unquestionably the character of food plays a part in causing renal diseases. The extractives of the richest meats are irritants that may aggravate albuminuria or help to produce it. The toxins produced by putrefaction of albuminous foods are more irritating than are the products of fermentation in other foods. Different meat foods vary as to the amount of toxins that they contain or can produce. Those that are least likely to ferment and are quickest digested are the blandest. No food has been found so well adapted to prevent nephritis or so suitable to the needs of a patient during its course as milk. Now, milk contains 4 per cent, of albumin; eggs, approximately 5 per cent.; and bouillon, 2 per cent.; but while either of the last may aggravate an albuminuria, the former will not. It is, therefore, not alone the percentage of protein that a food contains that makes such food more or less detrimental in nephritis, but its kind and its association with other ingredients, such as extractives. Treatment

When a case of acute nephritis first comes under treatment, it is best to enjoin rest in bed, to withhold all food for twenty-four or thirty-six hours, to give water freely, and to empty the alimentary canal by provoking purgation. Then milk should be given - at first in small quantities, at intervals of two hours. The quantity must be increased gradually until two quarts are taken daily. Milk is especially adapted to be the sole diet of those who have acute nephritis, because it more nearly meets-the demands of the system than any other single article of food. It is nutritious, quickly digested and absorbed, and therefore not likely to ferment in the stomach or bowels, and it possesses important diuretic properties.

Unfortunately, some patients cannot take milk with comfort or pleasure. This intolerance is often lessened or removed if, when the diet is begun, milk is administered in very small amounts, - one or two ounces at a time, for example, - and if the amount is slowly increased. Moreover, it is less likely to produce gastric distress if it is sipped instead of being drunk rapidly.

Milk is not palatable to some patients, and occasionally the attempt to force it upon them will cause so great disgust as to necessitate its discontinuance. Under these circumstances a substitute must be found. Many individuals who will not drink plain milk will take it when it is seasoned with pepper and salt, or is warmed, or is added to gruel, and sweetened. Salt is often harmful in nephritis. Much of it irritates the kidneys and its retention in the tissues sometimes helps to cause edema. Corn-starch, tapioca, and rice make dishes that are palatable with milk. They often enable one to give much of it without offending the sense of taste. Fruits may also be given with it. One must remember, however, that in proportion as the diet is varied, the danger of fermentation in the intestines is increased. If milk can be taken only in small quantities with other foods, it is necessary to see to it that water is drunk to supplement it, so that at least two quarts of fluid are taken daily.

The best adjuvants to milk in these cases are the starches and sugars, rice, corn-starch, tapioca, bread, boiled macaroni, baked potato, sweet fruits, and fruit-juices. After the preliminary period of withholding food, a water gruel may be given instead of milk. If the disease pursues a favorable course, more and more varied foods of the character just described may be used. It is, however, the universal judgment of the profession to-day that there is in this disease no perfect substitute for a milk diet.

When the urine becomes copious and the amount of nitrogenous matter voided in twenty-four hours is all that is to be expected, farinaceous foods may be prescribed in addition to milk. In a few days some of the sweet fruits and simpler vegetables may be given. When albumin disappears from the urine, an egg may be tried. During the time that albuminous foods are being added to the patient's dietary, close watch must be kept upon the effect of it - that is, upon the quantity of urine, the amount of daily nitrogenous excretion, and the amount of albumin and number of tube-casts, if any are found, in the urine.

When an egg can be eaten without harm, white meats may be tried, such as the breast of squab and chicken, a little boiled ham, or perfectly fresh fish. Red meats, rich in extractives, should not be eaten until recovery is established.

In some cases the stomach is intolerant at the onset of the disease. Water must then be given hypodermically and by the rectum to insure sufficient renal elimination. It may also be necessary to give some predigested milk by the rectum. As a rule, when the bowels are well emptied and the kidneys begin to eliminate more urine, vomiting ceases, for renal congestion and suppression of the functions of the kidneys are its cause.

So long as there is edema, a patient should be kept in bed. During the entire course of the disease he should be protected by warm clothing from sudden chilling of the skin. While he should be supplied with an abundance of fresh air, it should be kept at a uniform and genial temperature until recovery is established.

The activity of the skin can be promoted with benefit by rubbing it and by warm or hot baths.

Many mild cases need little medicine except a laxative at first, and its repetition occasionally during their course. Others require both careful hygienic and medicinal treatment.