DIABETES INSIPIDUS (POLY URIA).
Definition. — A disease characterized by marked increase in the quantity of urine, without any important qualitative changes in the elements of which it is composed.
Symptoms.—The malady may begin insidiously; but it is not unusual for it to appear suddenly, either following one of the causes which we shall name late; on, OT even without any appreciable cause. It may, in exceptional cases, manifest itself during childhood or in fancy.
[I have lately had under observation a young man, 16 years old, who was subject to excessive thirst since the first months of his life, the first word lie pronounced, at the age of S months, being " water." R. L-PINE.] When diabetes insipidus is not a primary disease, it may depend upon some nervous affection.
The urine is abundant, usually very pale in color, and is slightly acid. The specific gravity varies from 1002 to 1010. Consequently, the organic and inorganic principles are not present in any great qua_ntity, but, taking into account the daily amount of urine, it will be found that the total quantity of organic and in organic substances usually considerably exceeds the normal average. With re gard to the relative proportions, the chlorides are increased.
In inducing unilateral polyuria in a dog, for instance, by severing a splanch nic nerve, I have likewise observed the relative increase of the chlorides. This fact proves that the relative increase re sults from an elective permeability of the kidney with regard to these salts.
The quantity of urine voided during the twenty-four hours naturally bears a certain relation to the quantity of liquid ingested. As the cutaneous per spiration is usually greatly diminished in diabetic patients, there is, as a rule, less difference than in the normal state, between the quantity of fit-6d taken and that of the urine.
It is even possible that, in exceptional cases, the quantity drank in one day may be less than that of the urine voided during the same time.
In explanation of this paradox there are three hypotheses:— The first (which is the most natural) is the supposition that during this period the economy becomes impoverished as to water. This hypothesis agrees with
several conditions sometimes noticed in polyuric subjects, particularly the in creased density of the blood; in this case the weight of the patient should be less during the period in question. The second hypothesis, which, though not based on any special fact, does not seem irrational, premises that there is a much greater formation of water in the econ omy than in the normal conditions. In this case, there should be a diminution in the respiratory quotient: T. It is evident that, if there is more water formed, there is less CO., exhaled. This fact has been observed in certain condi tions of infectious fevers.
The third hypothesis appears to be less plausible. It consists in the sup position that the economy may absorb, particularly through the lungs, a certain quantity of watery vapor. It is known that in the healthy subject a copious ingestion of watery fluid is followed, during the two consecutive hours, by the loss, in the urine, of the greater part of the water taken. The same is not the case in diabetes insipidus; the elimina tion is less rapid, either because the kid ney has partially lost its functional elas ticity, which enabled it, in the normal state, to free the blood from an excess of water, or rather because the economy, being, relatively speaking, deprived of water, takes up a certain portion of that ingested.
In the same connection it may be noted that in the polyuric subject the difference existing in the healthy person between the urine of the twelve hours of the clay and those of the night is not noticeable.
Falck advanced the opinion that ad sorption is retarded in polyuric patients. This supposition is, in general, not very likely, but I would say that the dilata tion of the stomach sometimes observed in such patients might confirm it in cer tain cases.