ETIOLOGY - ACUTE DEGENERATION OF THE KIDNEYS.
The introduction of certain poisons into the body is regularly fol lowed by changes in the cells of the viscera. The poisons which exert this effect are ordinarily mineral poisons, such as arsenic, mer cury, and phosphorus; or the poisons of infectious diseases, such as diphtheria, typhoid fever, etc. According to the quantity and virulence of the poison received into the body, there are more or less marked changes produced in the cells of the viscera.
Small doses of such poisons, acting only for a moderate length of time, produce simple swelling of the cells. The cells are swollen, more opaque, more coarsely granular. They are not dead, nor broken down, nor do they contain any new substances ; the change in their appearance is due to the swelling of the network which forms a part of every cell. Under these circumstances there are either no changes at all in the blood-vessels of the viscera, or a slight congestion, with, perhaps, a little exudation of serum.
Larger doses of such poisons, or more virulent poisons, or a longer duration of the action of a poison, are attended by the deposi tion in the cell-bodies of granules of albuminous matter and globules of fat. At the same time there is a change iu the nutrition of the cells, and they are often broken and disintegrated. Under these con ditions there may be considerable congestion of the vessels and an exudation of serum.
Very large doses of such poisons cause the death of the cells of the viscera, a death which may take the form of coagulation-necrosis or of disintegration and breaking down of the cell. With these changes there will often be an excessive congestion of the vessels and a large exudation of serum.
As the kidneys are excreting organs it is rather natural to think that the substances which cause degeneration of the renal epithelium do so because they are excreted by the kidneys. But, as the same poisons produce similar degeneration in many other parts of the body, it seems more probable that the effect of the poison is produced in the same way that it is in the nerves, the muscles, the liver, and the spleen.
The well-known fact that temporary cutting off of the arterial blood from the kidneys in animals is followed by degeneration or death of the renal epithelium, has led to the idea that degeneration of the kidneys, especially in cholera, is due to ischtemia. This seems possible, but it is a theory not at all applicable to most cases of acute degeneration.
It is curious that so many different poisons should act in the same way. There seems to be nothing in common between the poison of corrosive sublimate and that of yellow fever, and yet the changes in the kidneys are practically the same.
The inorganic poisons, arsenic, etc., act according to the size of the dose taken. A small. dose produces only moderate degeneration of the renal epithelium, a large dose causes extensive necrosis with considerable exudation of blood serum.
The toxines of the different infectious diseases vary as to the ac tivity of their effect on the renal epithelium, as to the time in the disease when the degeneration takes place, and as to the frequency with which true nephritis is produced instead of acute degeneration. It is a question of much importance whether the same toxine produces degeneration or nephritis according to its dose, or whether two or more different toxines are necessary. In scarlatina and diphtheria, for example, the rule is that acute degeneration comes in the early days of the disease, acute exudative nephritis in the late days of the disease, and acute productive nephritis just after the close of the dis ease. Does this mean three different toxines, or that the same tox ine varies at different stages of the disease, or that the only difference is in the dose? • For clinical purposes the recognition of the fact that acute degen eration is the ordinary lesion of the infectious diseases is of much practical importance.