URAEMIA OR UREMIA.
It is well established that the principal function of the kidneys is to remove from the body a quantity of excrementitious substances. It is equally well established that a number of the diseases of the kidney interfere with this function and allow the excrementitious sub stances to accumulate in the blood and tissues. It is a matter of daily observation that persons who suffer from kidney disease exhibit symptoms of such a character as to give the idea that these persons are in some way poisoned. The sequence seems to be logical: disease of the kidneys, failure to eliminate excrementitious substances, ac cumulation of such substances in the blood and tissues, poisoning of the body by these substances, the development of symptoms due to the poisoning. To such a morbid process the name of "uremia" can properly be given. So in the year 1894 we find the following definition of uremia in Dunglison's Medical Dictionary : " Certain morbid phenomena, implicating the nervous centres more especially, due to retention of excrementitious substances in the blood which are normally excreted by the kidneys, as in Bright's disease." And this definition fairly represents the popular belief concerning uramia.
Unfortunately it is not possible to dismiss the subject in this easy way. We are confronted with many contradictions difficult of ex planation, and a review of the history of the subject shows that these difficulties have always been felt.
The simplest explanation of the phenomena of ummia—that they are due to the presence of urea in the blood—has been contended for by many observers from the time of Christison down to the present moment. The proof has been derived from the examination of the blood in human beings, and from experiments on animals.
It has been demonstrated over and over again that the blood of persons suffering from unumic attacks may contain a large excess of urea, that their serous effusions may contain large quantities of urea, and even that the urea may appear as a dry powder on the surface of the skin. It has also been shown that in a number of cases the out break of unemic convulsions is preceded by a diminution in the ex cretion of urine and of urea.
The experiments on animals have consisted in injections of urea into the veins, in the introduction of urea into the stomach, and in abolishing the function of the kidneys by ligating the blood-vessels or the ureters.
The introduction of urea in considerable quantities into the veins or into the stomach is well borne by animals provided that the kid neys perform their functions. The urea is eliminated with the urine. If, on the other hand, after the injection of urea into the blood the animal is entirely deprived of fluids, or the functions of the kidney are arrested by operation, then vomiting, diarrhoea, muscular contrac tions, and death regularly follow.
Ligature of the blood-vessels of the kidneys, or of their ureters, or extirpation of the kidneys is followed by an accumulation of urea in the blood and tissues. The animals have vomiting and diarrhoea, become stupid, and die.
The contradictions to this theory of urEemia were soon noted. Owen Rees was one of the first to call attention to the fact that pro longed anuria is not necessarily accompanied with renal symptoms. His illustrative case was a patient in whom one kidney was absent; the ureter of the other kidney became blocked by a calculus, and there was complete suppression of urine. The quantity of urea in the blood was much increased. The patient died, but there were no symptoms. Cases of suppression of urine lasting for a number of days are not infrequent, and the ordinary experience has been that it is precisely in these cases that unemic symptoms are absent, although death regularly follows.
More than this, Bartels and others have found that the blood drawn immediately after a urinic attack may contain no excess of urea. It is a matter of ordinary experience that ur2omic symptoms may come on in persons who are passing a normal quantity of urine of good specific gravity. So there seems to be no escape from the facts that complete suppression of urine is not regularly followed by urmraic symptoms, and that unemic symptoms may occur without an excess of urea in the blood, or a diminution in the excretion of normal urine.