2. Consequences of the Polyuria.—a. Polydipsia.—In diabetes mel litus, contrary to what obtains in many cases of diabetes insipidus, the polyuria is always the primary, and the exaggerated thirst (poly dipsia) the secondary, condition. The thirst is great and calls aloud for satisfaction, yet it is seldom so extreme as in diabetes insipidus.
b. Fluidity of the Blood.—The kidneys irritated by the sugar draw such a volume of water from the blood that a certain amount of thick ening of the latter may result. In such cases the proportion of solid constituents is increased, and examination shows a larger amount of haemoglobin and red blood corpuscles than normal. But this appar ent increase of the solid matter of the blood is always slight and is not constant, and there may be cases in which the fluid portion is normal or even relatively increased. We are still unable to formulate any definite law in this respect, notwithstanding the many data in our possession. It is possible that many interesting relations may be brought to light when, in addition to the examination of the blood, the amount of fluid ingested and the sensible and insensible losses of water from the organism are also taken into account.
c. Transpiration of Water through the Skin.—Diabetics usually have a dry skin and can with difficulty be made to perspire. The reciprocal relations of the skin and kidneys being known, it is very easy to see that the increased activity of the latter is responsible for the inactivity of the former. There are exceptions, however, to this rule, but these relate only to mild cases of diabetes and usually to those occurring in corpulent individuals. Instances of unilateral or local sweating are to be regarded from a very different standpoint; these are to be explained by a pathological irritation of the specific nerves regulating the cutaneous secretion. The insensible perspira tion is also diminished. Owing to the enormous drain through the kidneys, a relatively small amount of water is present to be disposed of by evaporation, but the absolute amount of water evaporated from the skin also is often lessened. That an absorption of water through the skin (negative insensible perspiration) takes place was formerly asserted but has not yet been determined with certainty.
Nitrogenous Constituents of the Urine.—We need add but little concerning the amount of nitrogen excreted; that is dependent upon proteid decomposition, and has been already referred to on page 88.
a. Ueea.—This is true especially of urea, which is responsible for about 80 or 90 per cent. of the nitrogen in the urine and therefore is subject to the same laws that regulate the excretion of nitrogen in general. Of much greater interest is the excretion of b. .Aunnonia."—The healthy man excretes from 0.5 to 1 gm. of ammonia per diem, and this amount may rise to from 1.2 to 1.5 gm. when meat constitutes a large part of the diet. In many cases of diabetes the same proportion holds, but in other cases the quantity of ammonia may be much greater. An excretion of from 3 to 6 gm. a day has been frequently observed (Hallervorden, Stadelmaun, Minkowski, Wolpe, von 7.N.Toorden, and others), and Stade'mann even found as much as 12 gm. a day in one instance. The highest fig ures belong ahnost exclusively to the stage of diabetic coma; those between the extremes, on the other hand, may be observed in given cases for periods of weeks and months.
So far as we know the animal organism excretes increased amounts of ammonia when acids, which combine with ammonia and prevent its union with carbonic dioxide to form urea, have obtained entrance into the blood ( Sell] n iedeberg, St; t del mann, Minkowski, and others). This rule appears to hold good with special force in diabetes, for (1) The nourishment of diabetics is an "acid" one. Much phos phoric acid is formed from the large quantity of meat, etc., ingested, and in particular a large amount of sulphuric acid is produced by the oxidation of the sulphur which every albumin molecule contains.
12) Besides this large quantities of organic acids are formed under certain circumstances in the diabetic organism. Aceto-acetic and beta-oxybutyric acids are much the most frequently produced of these organic acids. The conditions of their formation will be treated of later. With the exception of a few, as yet unexplained, cases (Wolpe), the presence of these acids in the urine is always accom panied by a profuse excretion of ammonia.