Definition.—A toxemia occurring in the course of various diseases, generally those of the kidneys, and due to a retention in the blood of certain products that are usually removed by these organs. It is not yet positively determined whether these retained products are the normal constituents of the urine or the results of some derangement in the process of metabolism.
Although most common in nephritis, uremia is found as a result of, or accompanying, other diseases; notably, typhus, typhoid, diphtheria, scarlet fever, gout, cholera, yellow fever, etc.
Etiology.—Brown-Sequard believed uremia to be due to a disturbance of an "internal secretion," which he believed the kidneys possessed. Traube's theory was, that it was due to an acute edema of the brain, and he cites cases of nephritis where a goodly portion of both water and solids are voided, and yet uremia exists.
Whenever the kidneys fail to void the normal quantity of solids of the urine, either from degeneration of the organs or from severe congestions, we have the conditions giving rise to uremia.
Strumpell well says: "Probably no one to-day doubts that uremia must be regarded as essentially an intoxication of the body by the retained products of tissue metamorphosis. Numerous experimental investigations have proved that, in animals, extirpation of the kidneys, or ligation of the ureters, will produce a symptom complex, characterized by vomiting, convulsions, and coma, almost completely analogous to the uremia of Bright's disease; but if we inquire what constituents of the urine are the particular occasion of the uremic phenomena, we can not as yet obtain any definite answer."
For a long time it was believed that urea played a chief part in the development of uremia, but the result of experiments upon animals does not support this view. It is possible to inject enormous amounts of urea into the circulation or into the peritoneal cavity of animals without any symptoms of poisoning. Voit did indeed show that the healthy kidneys remove from the blood the excessive amount of urea with extreme rapidity, and that accordingly uremic symptoms do really appear, if, while we are feeding an animal with large amounts of urea, we impede the excretion of the urea by a simultaneous withholding of water. Yet the amount of urea necessary for the success of this experiment is greater than can possibly exist in the uremia of Bright's disease; and, moreover, the withholding of water might also prevent the excretion of other matters; hence we must seek for other poisonous substances as factors in the production of uremia.
Many experiments seem to indicate that the potassium salts are especially poisonous, while some" authors have laid the blame mainly on the extractive matters, such as creatinin. Bouchard has sought to prove that certain alkaloid substances (urotoxins), which are probably developed during the digestion of albumins, and are always demonstrable in normal urine, occasion the phenomena of uremia; but to all these suppositions there are serious objections, so that really the substances which occasion uremic intoxication are as yet unidentified. It might be possible that the poison corresponding to uremia is not in every case the same.
Symptoms.—Uremia may be divided into acute and chronic, the symptoms depending somewhat upon the form the disease assumes. While acute uremia may attend any form of nephritis, it most frequently follows febrile conditions, such as scarlet fever, typhus fever, yellow fever, etc.
The acute form is characterized by the sudden appearance of nervous symptoms so usual to uremia, though in rare cases the acute form may be preceded by slight headache, general depression, more or less nausea, general malaise, and respiratory oppression.
The chronic form is characterized by the slower and more gradual invasion of the disease, so that months may elapse with the morbid processes involved, where but days, or at most weeks, terminate the acute form. For convenience of description the symptoms will be grouped according to the part affected,—cerebral, dyspneic, and gastro-intestinal.
Cerebral Symptoms.—These show a wide range, embracing, in their entirety, headache, delirium, mania, delusional insanity, convulsions, coma, and paralysis. In some the symptoms resemble an attack of epilepsy, being preceded by headache, the patient complaining of spots before the eyes, with impaired vision, more or less vertigo, ringing in the ears, nausea and vomiting, and finally terminating in convulsions—uremic eclampsia.
At other times the convulsive seizure may occur without any warning. The attacks may be general or local, as in Jacksonian epilepsy. During the interval between attacks the patient usually remains unconscious. The temperature may rise after an attack, though often the thermometer shows either a normal or subnormal range. Not infrequently blindness—uremic amaurosis—follows the convulsive attacks, and in rare cases occurs independently of them, though usually they are of but short duration, disappearing in two or three days, there being no structural changes in the visual apparatus. Uremic deafness is a rare result.
Following an attack, there is always unconsciousness for hours, though coma may develop gradually with the convulsions. The pulse is generally slow, full, and tense, though during a seizure it is small and frequent.
Mania may develop quite suddenly, the delirium being active in character, exhausting the patient rapidly and terminating fatally in a short time. At other times, the insanity may be mild in character, the patient being the victim of various delusions, that may lead to self-destruction, if the patient is not closely watched.
Uremic Dyspnea.—Very often, difficult respiration is the first symptom that causes the patient to consult the practitioner. At first it may be brought on by physical or mental exertion, or it may occur at an early hour in the morning-. As the disease progresses, the respiration becomes more and more involved, and is especially severe at night. Finally the patient is unable to lie down, but must assume the sitting posture in order to breathe. The breathing may be noisy and stridulous, or it may assume the Cheyne-Stokes type. This renal asthma is one of the most distressing symptoms of uremia.
Circulatory Symptoms.—The heart's action is labored, the pulse being slow and oppressed, save in some acute attacks or during convulsions, when it becomes rapid, though small and feeble.
Gastro-Intestinal Symptoms.—Gastro-intestinal irritation may occur early in the disease, and become persistent and distressing. The tongue is heavily coated and foul, the breath has a decidedly urinous odor, while the lips and gums are swollen and of a dark purplish color. Vomiting is sometimes persistent and distressing, lasting for days. Associated with this gastric disturbance is a uremic diarrhea, though it may be independent of the vomiting. According to Grawitz the irritant action of the ammonium carbonate on the intestinal mucosa may give rise to catarrhal or diphtheritic inflammation and ulceration.
Uremic pruritus is probably due to irritation of the cutaneous nerves by crystals of urea.
The temperature is usually normal or subnormal, though uremic fever may accompany the convulsions. A urinous or ammoniacal odor is quite characteristic towards the termination of the disease.
The urine is decreased in quantity, is dark, sometimes coffee-colored, and highly albuminous.
Diagnosis.—We must differentiate uremia from apoplexy (cerebral hemorrhage), cerebral tumor, meningitis, alcoholism, opium-poisoning, and infectious diseases. If you bear in mind certain characteristic symptoms, however, the diagnosis should not be difficult. The history, high arterial tension, accentuated second sound of the heart, albuminuria, low temperature, vomiting, foul tongue, and urinous breath and convulsions, can hardly be mistaken for the symptoms of any other lesion.
In apoplexy, the sudden loss of consciousness, the unequal or dilated pupils, and the absence of albuminuria and urinous breath, suggests cerebral hemorrhage.
In alcoholism, the pupils are commonly dilated, there are no convulsions, and the breath is not urinous or ammoniacal.
In opium-poisoning, the pupils are contracted. The eye-ground in uremia will reveal albuminuric retinitis.
It can be distinguished from the infectious diseases by the history and characteristic symptoms already noted; from meningitis, by the mode of onset, the delirium, and attendant fever.
Prognosis.—This must be guarded, as the disease is always grave, though not necessarily fatal.
Treatment.—The object of treatment is to eliminate the toxic excrementitious materials from the blood. To assist the kidneys in their work, we stimulate the skin and bowels by the free use of diaphoretics and hydragogue cathartics. A hot infusion of asclepias may be given freely, after the use of hot packs or the alcohol sweat, to keep up free diaphoresis. The compound powder of jalap (antibilious physic) should be given till free, copious stools are produced. Gelsemium, two to five drops in hot water, may then be given with benefit. Echinacea will be found beneficial in these cases. Where there is great prostration, the subcutaneous injection of a normal saline solution will prove of much benefit. Santonin, two or three grain doses of the first trituration, will increase the action of the kidneys and help in the process of elimination. Hot diuretic infusions, such as triticum repens, uva ursi, buchu, epigea repens, and althea, will stimulate the kidneys to increased action. For the convulsions, hypodermic injections of morphia will generally afford relief.