Chronic Interstitial Nephritis.
Synonyms.—Contracted Kidney; Cirrhosis of the Kidney; Granular Kidney; Gouty Kidney; Renal Sclerosis; Chronic Productive Nephritis without Exudation, etc.
Definition.—A chronic inflammation of the kidney, in which there is a growth of new connective tissue in the stroma, degeneration of the parenchyma attended by atrophy, and more or less cardio-vascular changes.
Etiology.—This is a disease of advanced life, and is most often seen after the age of fifty. Males are more subject than females, owing to greater exposure and dissipations. The causes that give rise to this form of nephritis are not always readily determined. Heredity seems to have some influence, the disease occurring in some families to the fourth generation.
Arterial degeneration also favors cirrhosis of the kidneys. Alcoholism and syphilis, undoubtedly, are forces that must be considered as etiological factors. Acute articular rheumatism is sometimes followed by interstitial nephritis, while malaria precedes chronic nephritis often enough to be regarded as figuring in the etiology.
Chronic lead-poisoning and gout may also cause it. Overeating and drinking, especially of meats and rich foods, causes increased work to be thrown upon the kidneys in their effort to get rid of the products of imperfect metabolism, and that irritation may give rise to sclerotic changes. Mental worry and overwork are not to be overlooked as predisposing causes.
Pathology.—The kidneys vary in size from those slightly reduced from the normal, to an ounce each. They are firmly imbedded in adipose tissue. The capsule is thick, and so firmly adherent, that, in stripping it from the kidney, portions of the latter come with it. The kidney is firm and resisting on section, and reveals a cortex very much thinned and atrophied and of a red or gray color. The pyramids are also of a dark-red color and reduced in size. The outer surface of the kidney is rough or granular, and frequently corroded with small cysts.
The microscopic changes as given by Delafield are as follows: "There is a growth of new connective tissue in the cortex, and also in the pyramids, which becomes more and more extensive as the disease progresses. In the cortex, the new tissue follows the distribution of the normal subcapsular areas of connective tissue, and is in the form of irregular masses, or is distributed diffusely between the tubes. In the pyramids the growth of new connective tissue is diffuse.
"The tubes, both in the cortex and in the pyramids, undergo marked changes. Those included in the masses of connective tissue are more or less dilated; their epithelium is flattened, some contain cast matter, while many are obliterated. The tubes between the masses of new connective tissue are more or less dilated; their epithelium is flattened, cuboidal, swollen, degenerated, or fatty. The dilatation of the tubes may reach such a point as to form cysts of some size, which contain fluid or coagulated matter. These cysts follow the lines of the arteries or tubes, or are situated near the capsules.
"Of the glomeruli a certain number remain of normal size, but with the tuft-cells swollen or multiplied. Many others are found in all stages of atrophy and of change into connective tissue. The atrophy seems to depend partly upon the growth of tuft-cells and intracapillary cells, partly on the thickening of the capsules, and partly on the occlusion of the arteries. If the chronic nephritis follows chronic congestion of the kidneys, the glomeruli remain large, with an increased growth of tuft-cells, or they become atrophied, but with the dilatation of the [capillaries still evident. The capillaries of the glomeruli may be the seat of waxy degeneration. The arteries exhibit the same changes as are found in exudative nephritis."
Symptoms.—Unless some complication sets in, like pneumonia, pleuritis, or pericarditis, and causes a rapid degeneration of the kidney, the renal symptoms may be latent for years, and only become manifest late in life, notwithstanding the fact that degeneration has been going on for years. The symptoms are so varied and complex, affecting so many organs, that it is better to describe them under the following heads:
Urinary.—The urine is increased in quantity, often amounting to two quarts, is of a light-yellow color, and may have a specific gravity of 1,005 or 1,010. Frequently the patient is compelled to void water several times during the night, and diabetes may be suspected. There is but little albumin present, especially in that voided in the early morning, and there are but few casts, and those are of a hyaline or granular form, while leukocytes and blood-corpuscles are rarely found.
During acute exacerbations, and later in the disease when there are marked cardiac changes, the albumin and casts are found more abundantly. The quantity is also diminished at this time. The amount of urea eliminated is diminished. In rare cases there may be hemorrhage from the kidneys. In rare cases the specific gravity, as well as quantity of urine voided, will be normal.
Cerebral.—Headache is nearly always a prominent symptom, and often quite difficult to relieve. Insomnia is not uncommon, especially where the patient is subject to neuralgia of various parts. Headache, with muscular twitching or drowsiness, is the forerunner of uremia or convulsions, and should always put the physician on his guard. The patient may become dull and drowsy, passing into coma, or there may be delirium more or less severe.
Cerebral hemorrhage, followed by coma or hemiplegia, is not uncommon, and is due to changes in the cerebral vessels. The hemiplegia and coma may continue till death, or may disappear in a few days, to be followed by a second or third attack.
Circulatory System.—There may be few symptoms present suggesting cardiac derangement, but a physical examination will determine the true condition. Inspection reveals the apex-beat displaced downward and to the left. Palpation confirms inspection, while percussion gives the dullness beyond the nipple line, confirming the diagnosis of hypertrophied heart.
Auscultation shows accentuation of the second aortic sound, and, where there is relative insufficiency, a mitral systolic murmur.
The pulse is hard, firm, and shows increased arterial tension. The hard, thickened, and tortuous vessels that are palpable show arteriosclerosis. When compensation fails, the cardiac asthma is a frequent distressing symptom.
Respiratory.—Dyspnea is one of the distressing symptoms of the advanced stage of the disease, though it may be one of the first symptoms to direct attention to the kidney. It may come on spasmodically, and is aggravated by exertion, or on lying down. The dyspnea may be due to several causes, such as contracted condition of the arteries with dilatation of the heart, to uremia, anemia, pneumonia, pleurisy, pericarditis, bronchitis, hydrothorax, and edema of the larynx and lung. Towards the end, the Cheyne-Stokes breathing may occur.
Gastro-Intestinal.—Nausea and vomiting are generally present at some stage of the disease, and suggestive of uremia. Attacks of gastritis or spasmodic vomiting may sometimes threaten the life of the patient. The breath is sometimes foul and urinous. Diarrhea is not uncommon, and may prove very exhausting.
Skin.—There is generally but little edema, and that in the ankles and extremities, though where there is cardiac dilatation or where compensation fails, dropsy may occur.
The skin is usually dry, pallid in color save in great cardiac complications, when it may become cyanotic. Pruritus is an occasional distressing symptom.
Special Senses.—An ophthalmoscopic examination may reveal the first evidence of Bright's disease, nephritic retinitis, flame-shaped hemorrhages being characteristic. Sudden blindness, uremic amaurosis, may be temporary or permanent. Ringing in the ears, more or less dizziness and deafness, sometimes occur.
Diagnosis.—This is not often made in the early stage of the disease. When the patient is passing large quantities of pale urine with low specific gravity, repeated examinations should be made of the urine voided, both night and morning. The presence of albumin and casts would suggest renal sclerosis. If, in addition, there is increased tension of the pulse, and the radial and temporal arteries are hard and sclerosed, and the apex-beat is displaced downwards and to the left, and there is accentuation of the second aortic sound, the diagnosis is quite certain. If to all these we have persistent headache, nausea and vomiting, dimness of vision, dyspnea, and coma, the diagnosis is positive.
Prognosis.—This disease is incurable, and the prognosis therefore unfavorable for a cure, though the patient's life may be prolonged for years with comfort to himself and the enjoyment of a fairly active life, provided that no complication or intercurrent affection prove fatal.
Where the diagnosis is made comparatively early, and the patient instructed how to live, what habits to avoid, and what methods to pursue, life may be prolonged for years. On the other hand, where there is cardiac dilatation and failing compensation, the outlook is bad. Uremic convulsions, coma, and paralysis also portend a fatal termination.
Treatment.—But little can be expected from medicines in the way of curing interstitial nephritis,, and our attention will be directed to preventing or retarding further retrograde tendencies, and meet the complications, as far as possible, as they arise.
The hygienic treatment is of great importance. The patient should observe regular habits, avoid severe mental or physical work, take exercise in the open air, dress warmly, and, as far as possible, avoid mental worry. Where possible, a removal to a warm and equable climate, where the patient can live a great deal in the open air, will be of marked benefit in prolonging life.
The diet should be nourishing, but easily digested. Meat may be eaten once a day. Vegetables (not much potatoes) and fruits may be eaten freely, and in some cases the cereals. Milk should be taken freely, and cocoa and coffee may be allowed occasionally, though, as a rule. they should be avoided. Alcoholic drinks, beer, and wines should be positively forbidden.
When there is gastric disturbance, only the blandest articles should be allowed, sherry or pepsin whey being generally acceptable to the most sensitive stomach. Pure water may be taken in moderation. The bowels should be kept soluble and the skin moist. A slightly increased arterial tension is not objectionable, and needs no special treatment; but where greatly increased, the strain upon the heart may cause rupture of the blood-vessels. For this, nitro-glycerin is highly recommended. Low tension is usually evidence of cardiac dilatation, there is edema, and the urine is scanty and albuminous. A decoction of apocynum, where the stomach will tolerate it, has a good effect, not only in relieving the edema, but in adding tone to the heart. An infusion of digitalis will also act kindly with these same conditions. For the uremic conditions the treatment will be the same as recommended under the head of uremia and acute Bright's disease.
Convulsions will be controlled by the hypodermic injection of morphia and pilocarpin. Any complication like pneumonia, pleuritis, pericarditis, bronchitis, etc., will be treated according to the conditions present. In fact, in treating interstitial nephritis, we treat our patient symptomatically, meeting the conditions as they arise.