URINARY DEPOSITS AND DIABETES.

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XXIII.

URINARY DEPOSITS AND DIABETES.

WE have already spoken of the symptoms of a stone, or calculus, as well as of gravel or sand in the kidneys, or passing thence through the ureter into the bladder, as regards the urinary organs; that is to say, as regards the mechanical irritation they produce, considered simply as foreign bodies, in which respect the different kinds of calculus matter pretty closely resemble each other; but the case is far otherwise in regard to their chemical composition, and in great measure also as to their physical properties; and no less so in regard to the causes which produce them, and, consequently, the means which must be used for their prevention.

When, therefore, we have reason to suspect the presence of any such matters in the urinary organs, or even the tendency to them, we examine the chemical condition of the urine, not only once or twice, but often, with a view to ascertaining not its condition upon one occasion only but repeatedly, that we may be enabled to form an opinion of the habit or diathesis of the patient in this particular; and a knowledge of this will enable us to reason not only forwards, to the probable character of any sediment or secretion which may be in the urinary organs either in esse or in posse, but backwards also to several antecedent conditions of the chylopoietic viscera which may have led to their formation.

It is known to every one that fresh urine from a healthy person is generally more or less acid, though this may vary from a very decided reaction to almost neutrality, the acidity being the greatest in urine voided just before meals, and the least when digestion is going on. This is generally believed to depend, not upon the presence of a pure acid but of super-salts of the alkaline or earthy bases which the urine contains. Now, although the stronger mineral acids, the sulphuric and the hydrochloric, are both present in the urine, those which we should naturally look for in a free state would be the uric (or lithic) and the phosphoric, not only from the great abundance of the former, but also because either would be liable to be set free, by the former entering more readily into combination with the alkaline and earthy bases which the urine contains: they do not, however, exist in a free state in the urine of health, but certain of the bases are not perfectly neutralised, and form super-salts with those acids; or, in other words, they form super-urates and superphosphates.

It is probably upon the presence of super-phosphate of soda that the acid reaction of the urine depends, since it is questionable whether the super-urate is ordinarily present, though the urate of ammonia exists in great abundance, and is readily soluble in water, and in urine in its normal condition. Now this latter salt is, of course,

readily decomposed by the presence of any stronger acid than the uric, which, being insoluble, will of course be precipitated, and accordingly it comes down in the form either of an amphorous sediment, or of minute grains, resembling powdered cayenne pepper; for though uric acid may thus be rendered insoluble in the urine, it does not generally come down in the shape of crystals, since, as Dr. Bence Jones has taught us, the hydrochloric, which is the acid upon which excessive acidity of the urine mainly depends, does not immediately decompose urate of ammonia, the combination in which the uric acid exists in the urine, but renders it less soluble, throwing it down in the form of an amorphous powder. We have, then, two forms of uric acid deposits, the free crystalline uric acid itself, which can only appear when the urine contains a great excess of hydrochloric acid,—and the urate of ammonia, showing itself in amorphous sediments, generally of a pinkish fawn or drab-colour, redissolved by heating the urine, which the free lithic acid is not: but independently of being of limited solubility in cool urine, which is normally acid, it may also make its appearance, being thrown down as shown by excess of acid from its being actually in greater quantity than in perfect health, either absolutely or in proportion to the quantity of fluid secreted. In the majority of instances, the precipitate is dependent upon both these causes.

The immediate or chemical cause, then, of the depositions of uric acid, is excessive acidity in the urine. The probable cause of this acidity is to be found in the stomach, the acidity of which varies, as we have seen, inversely as to that of the urine. In cases of extreme irritability of this organ, there is, probably, during digestion, a rapid secretion of hydrochloric acid; during this process, the acidity of the urine would be diminished, or would altogether disappear; but after a reabsorption of the acid, the urine would become proportionally acid; this shows the fallacy of observations upon the acidity of the urine made only once in twenty-four hours, since it is probable that at certain times in the day the urine of a person passing free uric acid may be alkaline. The chemical cause of the deposit of the noncrystallised sediment, the urate of ammonia, is either excess of acid or an unusually large quantity of the urates, often both causes combined. The morbid causes of this condition may be either gastric irritation, as in the case of the uric acid crystals; gout or rheumatism, or other febrile disturbance; or a deficiency in the quantity of water proportionate to the solid contents of the urine, as in the case of obstruction to the portal circulation. In the two latter conditions the urates alone are precipitated, without any crystals of uric acid; but in the former uric acid also is always present if there be a considerable acidity of the urine.

The diagnosis of these forms of disease must depend upon the examination of the deposits both by the microscope and chemically; the latter, however, when there is the least doubt, is the only means to be relied upon. The microscopic appearances of crystalline uricacid present every combination of the rhombic prism, though these

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Uric

may arrange themselves into forms very likely to mislead.* acid is destroyed by heating it to a red heat in a platinum spoon, it burns in fact. When uric acid is treated with a little nitric acid, and then heated to dryness, it becomes of a deep red, which is always increased in intensity by the addition of vapour of ammonia. The urate of ammonia is, for the most part, thrown down as an amorphous sediment; as regards the test of burning, and of the addition of nitric acid, it comports itself like the uric acid; but there is this difference ;-that though both are dissolved by carbonate of potass, the utrate of ammonia evolves ammoniated fumes when the solution is heated, which is not the case with uric acid; and what is still more to the purpose, urate of ammonia is readily dissolved by heating it in water, which is not the case with uric acid. This last test enables us to determine whether urine which obviously contains urate of ammonia, contains likewise uric acid, a question which may always be answered by heating the liquid, when if it becomes perfectly clear the deposit is urate of ammonia, without uric acid.

These two kinds of deposit of uric acid require different modes of treatment according to their cause. When the crystalline uric acid is present, either with or without the urates, the medicinal treatment must consist in the exhibition of alkalies, and the dietetic, in abstinence from acids and all substances likely to become so. For the first, the liquor potassæ, carbonate of potass, saline draughts of citric acid and citrate of potass, and phosphate of soda may be employed; the carbonates of soda and magnesia are sometimes used, but the first is open to the objection, that the urate of soda is insoluble; and the latter, that it sometimes forms concretions in the alimentary canal. As regards the regimen, we must prohibit the use of vegetable acids, and enjoin a very moderate use of substances containing much starch or sugar, since they readily form a vegetable acid in the stomach. To promote the removal of acid by the skin, and the free evolution of carbonic acid by the lungs, is an indication of still greater moment; for this cause moderate exercise should be used.

The deposit of the amorphous lithates, being dependent upon no great excess of acid in the urine, (when unaccompanied by free lithic acid,) should not be treated with alkaline remedies, at least not as a general rule, since we should rather turn our attention to the disease of which they may be symptomatic. When the deposit occurs as the consequence of slight dyspeptic derangement, or excesses or irregularities in diet, a little additional liquid, as an extra glass of water or soda-water, or a gentle diuretic will, as Dr. Bence Jones observes, dissolve the urate of ammonia, by increasing the quantity of liquid in the urine: whilst we must look to a very moderate diet, and moderate exercise, for effecting a cure. But in those diseases in which (as we have pointed out) the urates come down through a deficiency of water to hold them in solution, owing to disease in the course of that circuit through which water passes from the intestines to the arterial system, diuretics, whether gentle or of a more powerful kind,

* Bird on Urinary Deposits.

will have little or no effect, until we obviate the primary disease, if it be possible to do so, or if not, till we have in some degree relieved the circulation, by measures adapted to the particular affection.

In connection with urate of ammonia we may allude to the remarkable colouring matter purpurine, which is sometimes present in considerable quantities, but never comes down as a deposit unless urate of ammonia be also present, which has the property of removing the great mass of purpurine from the urine, and assuming thereby a purple tint.* Urate of ammonia, thus coloured, varies from a pinkish drab or fawn colour to that of a rich carmine; so deep, indeed, is the colour that urine in which it has been suspended has not unfrequently been supposed to be coloured with blood; so close, sometimes, is this resemblance, that it is necessary to satisfy ourselves of the absence of the latter by the appropriate tests. It also interferes so much with the solubility of the urate of ammonia with which it is united, that long continued boiling is necessary to effect its solution; familiar instance of this is to be found in the pink stain or fur, as it is often called, which adheres to the bottom of the utensil, and for the removal of which the housemaid is often obliged to have recourse to hot water and soda or potass. The brightness of the colour when this deposit is collected in a filter, and the fact that alcohol will separate the purpurine from the urate of ammonia, by dissolving the former and leaving the urate, are sufficient characteristics. In examining urine highly coloured by purpurine, care is requisite to avoid confounding it with the muddy deposit of uric acid thrown down by nitric acid with albumen. This property which purpurine possesses of precipitating urate of ammonia gives it considerable importance in reference to urinary calculi, which thereby receive strata of urate of ammonia which would otherwise have remained dissolved in the urine. It possesses also a further pathological importance from its indicating an impediment to the free secretion of bile by the liver, or perhaps more correctly the purpurine being a more highly carbonised substance than any in the urine, is the form in which that principle appears when the kidneys take on a supplementary action to the liver, and through the liver to the lungs. It does not, as Dr. Golding Bird remarks, universally occur in phthisis; and the reason of this is, that, as we have elsewhere pointed out, there may be great disorganisation of the lungs in phthisis, yet no considerable defect in the decarbonisation of the blood by these organs, owing to the diminished quantity of the blood itself: but if the lungs have become rapidly obstructed, whether by phthisis, capillary bronchitis, or the various other diseases which we have shown to produce that effect, purpurine soon appears in the

urine.

Oxalate of lime is another deposit of frequent occurrence in the urine, chiefly, perhaps, important from its tendency to form concretions in the kidneys and bladder. Dr. Bence Jones considers it of very little consequence in other respects, from its being found in the

* Dr. Golding Bird, "Urinary Deposits, Philada. ed., p. 158.

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urine of persons in good health, as well as of those in very opposite states of disease. Dr. Golding Bird, on the contrary, regarded it as indicative of derangement of the general health, and therefore of great pathological importance, besides its tendency to form calculi of the most painful form. The truth will probably be eventually found to lie between these two opinions; the frequency of its occurrence, for which fact we are in the first instance indebted to Dr. Bird, is sufficient to awaken our attention to the importance of this form of deposit, whilst the fact of its being often found in the urine of healthy persons, proves that it does not necessarily indicate any great deviation from health, though it may point out to what form of diseased action the patient in question may be more particularly liable. There can be little doubt that a tendency to deposit oxalate of lime is

associated with an excessive secretion of uric acid and urea from the kidneys, that it is often accompanied by great nervous irritability, languor, emaciation, hypochondriasis, and want of nervine and physical energy, consequent upon a drain upon the system analogous to what may be seen in spermatorrhoea and in leucorrhoea in females.

The diagnosis of this deposit is very simple; if the urine be allowed to stand in a tall glass for about an hour, and the greater part of it decanted, the portion remaining at the bottom will be found under a half-inch glass to contain minute octohedral crystals. It is a remarkable fact that oxalate of lime has a great tendency to alternate in the same patient with uric acid or urate of ammonia.

The treatment of the diathesis, if it may be so called, consists in attending carefully to the state of the skin and in regulating the diet. Good mutton once a day, or when the appetite admits of it and the patient requires support, a slice of cold mutton also at breakfast; moderate use of fruit, vegetables, avoidance of pastry, cocoa once a day in preference to tea or coffee; barley water or toast-water, or good water itself, for drink, unless the state of the patient seems urgently to call for stimulants, when a little weak brandy and water may be allowed. Nitric acid, or the nitro-hydrochloric extemporaneously prepared may be given, in a bitter infusion, twice or thrice a-day. The use, however, of the acids must be carefully watched, as they will after a time produce urate of ammonia in the urine; when this begins to be the case they must be discontinued. When there is anæmia, tincture of sesquichloride of iron should be employed; when much nervous debility, sulphate of zinc.

An excess of sulphates exists sometimes in the urine, though it does not show itself in the form of any deposit; the sulphates of soda and potass being always present, whatever be the condition of the urine; the sulphuric acid may, however, be precipitated, and its quantity ascertained, by adding a solution of chloride of barium, taking the precaution of adding a few drops of hydrochloric acid to ensure the solution of any phosphate of baryta that may be formed. Dr. Bence Jones gives the following summary of his observations on the occurrence of sulphates in the urine:

1. That the sulphates in the urine are much increased by food, whether it be animal or vegetable.