A text-book of urine analysis; for students and practitioner of medicine

Preface

In the following pages the subject of practical urine analysis is presented in a concise manner adapted to the requirements of the medical student in systematic class work, and also to the wants of the medical practitioner, who has occasion to make something more than the usual simple qualitative tests in urine examinations. A considerable number of quantitative methods are carefully £$ described, and in such a manner, it is believed, that any one with a slight previous training in the manipulation of chemical apparatus can follow them. On the other hand methods of doubtful applicability are consistently excluded.

This book contains much of the matter which appeared some years ago in the author's " Chemical Physiology and Urine Analysis." That work being out of print, the chapters on urine analysis have been rewritten and enlarged to appear, with additional chapters, in the present form. Two chapters are devoted to the microscopic examination of sediments.

While the book is essentially one of analysis, not of diagnosis, numerous references are made throughout the text to the clinical significance of what is found by the various tests, and in the appendix a section is devoted to a tabular statement of the relation of pathological condi-

IV

PREFACE.

tions to the chemical composition of the urine. For many valuable suggestions in this direction the author is indebted to his colleague, Dr. Frank S. Johnson. He must also acknowledge the assistance of Dr. Frank X. Walls in the preparation of illustrations, and of Mr. Frank Wright in the reading of proof.

The Author.

Chicago, March, /goo.

Tables and Notes 223

Chapter I

OUTLINE OF TESTS. PRELIMINARY TESTS

The importance of an accurate knowledge of the bodies excreted by the urine has long been recognized and elaborate investigations have been carried out to determine the nature and quantities of these substances, some of which appear normally in health, while others are found only during the progress of disease.

Experiment shows that normally certain products occur in the urine in relatively large amounts, and give to it its prominent characteristics, while of other products the amounts present are so minute that their detection is a matter of no little difficulty.

Certain grave disorders are accompanied by the appearance of certain substances in the urine, and where the chemical or microscopic tests for the latter are simple and unquestionably correct we have at hand a convenient aid to diagnosis. In many cases, however, it is true that we are unable to trace the relation between small amounts of substances occasionally appearing in urine and any specific disorder or condition of the body. The detection of such substances is naturally without value in diagnosis, at the present time.

Yet it would be unwise to neglect the study of such traces because, as medical science progresses, new relations are from time to time brought to light which give value to data which at one time may have been considered wholly unimportant. Complete handbooks on the urine give prominence to many topics which will not be touched upon in what follows because we are here concerned with phenomena, everywhere recognized as important and the bearings of which, in the main at least, are understood.

In the practical analysis of urine, such as is customary for clinical purposes, comparatively few tests are required, and little apparatus is necessary beyond that already used for other examinations. Frequently a single test is sufficient to determine all the physician needs to know ; for instance, regarding the presence or absence of sugar or albumin.

In the following pages those tests and processes will be described which have been shown by experience to be amply sufficient for all practical requirements. Some of these are qualitative, others quantitative, and may be tabulated as follows :

i. Observation of color and odor.

2. The reaction, whether acid or alkaline.

3. The tests for albumin.

4. The tests for sugar.

5. The tests for the characteristic biliary acids and coloring-matters.

6. The various tests for blood.

7. Tests for other coloring-matters.

8. The examination of the sediment.

Cv

.

Determination oi

4->

<D n.

*• ctf

•iH c

OS

O* the amount of albumin, susrar.

uric acid. urea.

phosphates, chlorides.

The above includes the usual and important tests. A few others will be given in the proper place ; for instance, tests for acetone and diacetic acid, which under circumstances may have importance.

Normally, urine contains as its most important constituents urea, sodium chloride, certain phosphates and urates, and smaller amounts of other substances as hippuric acid, xanthin, creatinin, traces of phenols, etc.

Several writers have given the results of complete urine analyses in tabular form. These results are not very concordant, as might be expected from the character of urine itself. Two tables often quoted will be given here for comparison.

According to Thudichum the average volume of urine passed per day is 1400 to 1600 cc, and the solid matter contained in the daily excretion he gives as follows, for a man weighing about 140 pounds.

Urea -

Creatin and creatinin

Hippuric acid

Cryptophanic acid -

Biliary acids

Acetic acid

Grams.

30-40

0.75

O.OI2

Grains.

Formic acid - - - - - - 0.05

Sulphuric acid, SO a - - - - 2.00

Other sulphur combinations - - - 0.20 Alkaline phosphates - - - - 3.66

Earthy phosphates - - - 1.28

Potassium and sodium chlorides - - 1 1 . 50

Traces of other bodies are given by Thudichum, but in amounts too small for determination.

Another table given by Parkes presents a better arrangement, and is here given ; the figures refer to the amounts excreted in twenty-four hours by a man weighing about 145 pounds.

Grams.

Hippuric acid

- 0.40

Creatinin -----

0.91

Organic acids and pigments

- 10.00

Sulphuric acid, S0 3

2.01

Phosphoric acid, P 2 5

Calcium -----

0.26

Magnesium -

Potassium -----

2.50

Sodium _ _ _ -

- II.O9

Chlorine -----

7-50

Ammonia -

It is evident that the character of the urine depends very largely on the diet, and this is shown in a clear manner by the figures in the following table, which were obtained by Bunge by the analysis of the urine of a healthy man, fed first on a meat diet, and later on one of wheat bread with salt and butter. Water was freely drunk in both tests.

Meat diet.

Bread diet cc.

cc.

mie in twenty-four hours.

Grams.

Grams.

Urea -

- 67.2

20.6

Creatinin

2.163

0.961

■ 1-398

0-253

Sulphuric acid, S0 3

4.674

1.265

Phosphoric acid, P 2 5

■ 3-437

1.658

Lime -

0.328

Magnesia

■ 0.294

0.139

Potash - i-3H

Soda -

3-991

3.9 2 3

Chlorine -

4.996

These figures represent, of course, extreme cases, but their practical importance is readily recognized.

Pathologically there may appear albumin, sugar, blood, pus, bile pigments and acids, and a number of other bodies insoluble, or of slight solubility, which usually appear as a sediment.

We turn now to an explanation of the various preliminary tests employed.

Specific Gravity

The density or specific gravity of the urine secreted in twenty-four hours, varies in health between rather wide limits, probably between 1.005 an( ^ 1*030. 1.020 may be taken as about the mean value at 15 C.

The specific gravity depends primarily on the amounts of liquid and solid food taken, and on the loss of water from the skin by perspiration. When

ITRINE ANALYSIS

II this loss is great the specific gravity of the urine is correspondingly increased, other things being equal.

In disease the density may be lowered below or increased above the normal value.

For an absolutely exact determination of the density a the use of the pycnometer, Mohr-

Westphal balance, or other apparatus is necessary, but for our purpose the urinometer, or density bulb, is sufficiently accurate. This little instrument is shown in the adjoining figure.

The urine to be tested is poured into a narrow jar, about one cm. wider than the bulb, and after the air bubbles have escaped the urinometer is immersed in it. When it comes to rest the degree at which it stands is read off below the siwface. Usually the last two figures only of the density are marked on the stem, as 25, instead of 1.025, and these are often given as the density.

As the density of urine decreases about one degree for an increase in temperature of 3 to Fi g- r - 5 C. it is important that the test

be made at a definite known temperature, as 15 or 25 C. Urinometers have usually been graduated to give the correct reading at a temperature of 15.5 C. (6o° F.). But at the present time we have them for the temperature of 25 C. (77 F.), because this is with us a more common house temperature than the lower one. It is convenient to have the instrument indicate the correct specific gravity without the necessity of cooling. The specific gravity of urine varies approximately as does that of water, with changes of temperature. A table in the appendix shows the rate for water, and by the use of this a correction can be made.

By noting the amount of urine passed in twenty-four hours, and the density of the mixed liquid, a rough determination of the solid matters contained in it can be made. For this purpose it is simply necessary to multiply the last two figures of the density by 2.33 (known as the coefficient of Haeser\ which gives the approximate number of grams in a liter. By proportion the amount for the day can be calculated from this.

For example, 1,400 cc. of urine was passed, and its density was found to be 1.024, Then, 24 X 2.33 = 55.92, and, 1,000 : 1,400 : : 55.92 : x = 78.288.

This calculation is frequently of service.

As indicated above a variation in the specific gravity of normal urine may be due to several causes, the most important of which are changes in the volume of water drunk or the weight of nitrogenous food and salt digested. The amount of urine excreted daily may be taken as 1,500 cc. in the mean. Assuming that 15 grams daily is the salt consumption and that it is all excreted with the urine we have through this factor alone a specific gravity of about 1.007. Assuming further that 150 grams of nitrogenous food (considered as pure albumin) are consumed daily and that four-fifths of this amount is daily excreted as urea, the weight of the latter in the urine would be 43 grains. This alone would produce a density of nearly 1.008 and give a percentage composition of 2.84. Combined with the other substances in urine the relative effect of the addition of urea would be o-reater. All of the solids of the urine have a specific gravity greater than that of water and their presence therefore adds to the specific gravity of the excretion, but changes in the density, due to changes in the amounts of uric acid, phosphates, sulphates, etc., passed, are of less importance because of the relatively small quantities of these substances normally present.

If, with the food consumed normal, the water taken is small in amount, or if a large amount is lost from the skin as perspiration then the density of the excreted urine must be correspondingly higher. A large volume of water consumed or little evaporation from the skin will give a urine of lower density. It is plain, therefore, that great variations in the specific gravity of the urine may occur and from perfectly normal causes.

In disease even greater variations may occur, one of the most characteristic and important being that due to the presence of sugar in diabetes mellitus. Here the density may reach 1.040 or higher, while the voltime of urine is above 1,500 or 2,000 cc. in the twenty-four hours. A high specific gravity with large volume is always suspicious and suggests presence of dextrose, although occasionally it may be due to presence of large doses of soluble salts taken into the system as remedial agents. A low specific gravity with small volume of urine must also call for investigation, as this points to the absence of, or marked decrease in, the normal constituents from some cause. A lower density is observed in diseases where the elimination of urea is slower because of hindered tissue changes, in conditions of malnutrition in general, and in any disease involving the structure of the liver itself. In acute yellow atrophy of the liver, for instance, urea is much diminished, and the specific gravity low.

The diminution in excreted chlorides, with normal consumption, in certain diseases is also a factor in causing low specific gravity. This may follow when the salt consumed is eliminated temporarily in various exudations or effusions rather than by the normal channel.

Some of these indications will receive attention later during the discussion of the tests for the common normal and abnormal urine constituents.

Reaction

In health the reaction of the mixed urine passed through twenty-four hours is always acid.

This normal acid reaction is supposed to be due to the presence of acid phosphates and to small amounts of uric acid and to other free organic acids. The

IO URINE ANALYSIS

reaction can be observed by the aid of sensitive litmus paper, but the absolute amount of free acid is very small.

Occasionally urine is passed which gives the so-called amphoteric reaction with litmus ; that is, it turns blue paper red and red paper blue. It has not been found possible to connect this phenomenon with certainty with any definite pathological condition ; it has, therefore, no special clinical significance at the present time. Some hours after a hearty meal an alkaline reaction is frequently observed, giving place soon to the usual acid condition. This alkaline reaction may be due to the presence of small amounts of trisodium phosphate formed during active digestion. The administration of alkaline carbonates, or of certain organic salts, as malates, acetates, tartrates, or citrates, which yield carbonates by final decomposition, may also occasion an alkaline condition. It should be observed that the character of the food consumed has much to do with the quality of the urine as regards acidity or alkalinity. In the consumption of products rich in proteids the oxidation of the sulphur gives rise to sulphuric acid which converts the alkali phosphate of the blood into acid phosphate before excretion. With a diet low in proteids the acidity is greatly decreased. Sometime after it is voided urine always becomes strongly alkaline in reaction, but this change may be delayed for days or weeks even. It is brought about by the decomposition of urea, which is usually a result of bacterial action. In this decomposition ammonium carbonate is formed, the odor of which

PRELIMINARY TESTS I I

often becomes very strong. Anything which prevents or impedes the bacterial activity tends to maintain the ordinary acid or neutral reaction. Salicylic acid, thymol, chloroform, volatile oils, and other antiferments behave in this manner, and are frequently added to specimens of urine to preserve them for investigation. For the preservation of ioo cc. of urine one-fourth of a gram of salicylic acid is enough.

Sometimes the decomposition of the urea takes place in the bladder, the voided urine having then a very marked alkaline reaction and strong odor, usually. Such a change may be brought about by the progress of disease, or may be induced by the introduction of a dirty catheter into the bladder. This carries the organism capable of splitting up the urea, and the condition once established may be maintained for a long time.

Ammonium carbonate results from the reaction. This may be distinguished from the fixed alkalies (hydroxide or carbonate of sodium or potassium) by a very simple test. A piece of sensitive red litmus paper immersed in alkaline urine becomes blue. On drying the paper the color due to the non-volatile alkalies persists, while that of ammonium carbonate disappears. The test has some practical value as it is necessary to distinguish between the alkalinity of urea fermentation and that of an excess of fixed alkali occasionally present. For these tests only fresh sensitive paper can be safely used. The conversion of urea into ammonium carbonate is represented by this equation :

In highly colored urines it is not always easy to observe the reaction with litmus paper. In this case a method often used in the examination of blood to determine its alkalinity may be applied. This consists in immersing small disks of plaster of Paris in neutral litmus solution and then drying them. A few drops of urine are placed on a disk and allowed to remain some minutes. The urine is then washed off leaving a bluish or reddish spot indicating the reaction.

An accurate determination of the acidity of urine can not be readily made, but approximately a value may be obtained by adding a few drops of phenolphthalein to ioo cc. of urine, and then running in tenth-normal sodium hydroxide solution until a permanent pink color is secured. At this stage the acid phosphates of the type H 2 NaPO are converted into the alkali phosphates of the type HNa 2 P0 , and for each cubic centimeter of alkali used 12 milligrams of H 2 NaPO may be calculated as present. But on account of the color of the urine itself the process is at best somewhat uncertain.

To approximately determine the alkalinity add to 100 cc. of urine a few drops of phenolphthalein, and then tenth-normal sulphuric or hydrochloric acid until the color disappears. If the alkalinity is due to sodium carbonate, for each cc. of the acid used, calculate 5.3 milligrams of Na 2 C0 as present. If due to Na PO each cc. of alkali used corresponds to 8.2 milligrams. All such tests should be made in a beaker with a wide bottom placed over white paper so as to disclose a change of color as clearly as possible. For the preparation of the standard acid and alkali solutions used in these tests see the appendix.

Odor

The odor of urine is not easily described, as in health it is sui generis and characteristic. Normal urine contains traces of complex aromatic bodies, the exact nature of which cannot in all cases be given. These substances are more abundant after a vegetable than after an animal diet, and are especially noteworthy in the urine of persons whose food contains such vegetables as cabbage, radishes, parsnips, asparagus, or the spices. It is well known that certain substances given as remedies give rise to distinct odors in the urine. The administration of turpentine imparts to the urine an odor of violets.

As the odor so largely depends on the nature of the food it may be much modified even in health, and in disease may be characteristically changed. The ammoniacal odor of urea decomposition in the bladder has been referred to, and the peculiar sweetish odor of diabetic urine has long been noticed.

But it must be remembered that many strong odors may be developed in the urine soon after passage by the action of ferments other than the micrococcus urea which yields ammonium carbonate. In some cases these give rise to what may be called a putrefactive odor.

Color

The color of urine is described as straw-yellow.

Many causes, however, may produce a change in this shade, leaving the urine still normal. As can be readily seen the color is closely dependent on concentration and must, therefore, vary with the amount of liquid taken into the stomach.

Certain foods from the vegetable kingdom possess characteristic coloring-matters which pass, more or less changed, into the urine. As long as the latter is acid the presence of these may not be noticed, but w r ith a change of reaction a change of color may follow, usually to reddish.

Santonin imparts a yellowish color to urine, reddened by alkalies. In pathological conditions the color of urine is often characteristic and of great importance in diagnosis. The presence of blood, for instance, is indicated by a more or less sharp shade of red, bile by a peculiar greenish brown, especially noticeable in froth produced on shaking. The urine of diabetes mellitus is generally very pale, while the urine of fevers is usually highly colored not only from the diminution of water, but also from the presence of abnormal coloring-matters. Different shades are produced by the presence of altered blood and bile constituents, which will be referred to later. The real color of the urine is often obscured by loss of transparency due to precipitation. Normal urine is generally perfectly transparent when passed, but sometimes cloudy from presence of a suspended precipitate of mucus or phosphates. On becoming alkaline a precipitation of earthy phosphates usually follows. A precipitate of urates, without change of reaction, often takes place by simply lowering the temperature of the urine. This precipitate, however, disappears on the application of a slight heat to the urine, and leaves the latter clear for examination of color.

Clinically, the color indications of greatest importance are those due to the presence of derivatives from the blood or bile. These may be unaltered elements of the blood or bile or decomposition products of their essential coloring-matters.

In a following section on the tests for abnormal coloring-matters in urine this question will be again taken up.

Chapter II THE TESTS FOR ALBUMINS

Albuminous bodies do not occur in normal urine except, perhaps, in mere traces. Numerous investigations have been published on this subject, and while some of the recent ones would seem to show the probability of a physiological albuminuria, others, seemingly as thorough, lead to quite the opposite conclusion.

Temporarily, it is true, albumin may be found in the urine of healthy individuals, as after the consumption of large quantities of egg albumin, or after the action of some cause producing a sudden alteration of the blood pressure, but the amounts found in such cases are too small, and their occurrence too rare, to permit them to be classed as anything but accidental. It is certain that the presence of any appreciable amount of albumin in the urine and the persistence of the same must be looked upon as a pathological phenomenon and one of the greatest importance to the physician.

Albumins may appear in urine from several sources, most frequently, probably, because of some structural change in the tubules of the kidneys which permits a filtration from the blood. But this is not always the case as they may appear from sources in no way dependent on renal disorder, from lesions of the ureters, bladder, or urethra, for instance, in which case blood or pus may be present. Ordinary serum albumin is the usual, but not the only proteid body which may appear in urine. Half a dozen or more modifications have been described as occurring under different circumstances, but the evidence for some of these appears to be of doubtful character. Certain forms are not readily detected or identified. In what follows, tests will be given for those proteid bodies which can be detected with certainty and whose presence has some definite clinical importance.

i. Serum Albumin

The presence of serum albumin in the urine is a characteristic of what is ordinarily termed albuminuria. As intimated above albuminous bodies may appear in the urine from different sources. The presence of serum albumin suggests (a) a functional or structural disorder of some part of the essential tissue of the kidney, in which case we have renal albuminuria or true albuminuria, or (b) a lesion of some part of the urinary tract below the kidney, in which case we have what is called false or accidental albuminuria.

Renal albuminuria is the condition appearing in Bright's disease or acute parenchymatous nephritis and in other pathological conditions in which a change of the diffusion membrane is involved. It is also frequently induced by derangements in the circulation due to heart diseases, high fevers, etc., which in turn may react and give rise to a derangement of the kidney itself. That is to say, the causes producing certain febrile conditions may extend to the structure of the renal filtering apparatus and so alter its condition that the passage of albumin is no longer hindered but becomes continuous.

Under all such circumstances the albumin passing through the kidney is generally accompanied with something which suggests its origin. There may be here an excessive amount of the epithelial lining of the tubules, or plugs of coagulated albumin, mucus, or of the wax-like, partially degenerated albumin known as lardacein, all in the form of "casts" of the uriniferous tubules. These may be readily seen and recognized by the microscope.

As intimated above, false or accidental albuminuria can originate from several causes and in general is a condition of far less clinical importance than the other. It is usually possible to determine by a few examinations the real nature of the disorder by aid of the facts just mentioned.

Because of the very great importance of the subject to the physician, much attention has been given to the question of albumin tests, and the number of reactions proposed for its detection reach, possibly, the hundreds. Many of these are of such extreme delicacy and so easy of execution that to make a choice of a few is by no means a simple matter.

The best of them depend on the fact that the soluble serum albumin, which finds its way into the urine, can be coagulated and made visible as white flocculi, or as a white cloud when present in small quantity. Of the various methods of producing this coagulation, only those will be mentioned which are most characteristic, and practically the most useful.

Qualitative Coagulation Tests

Coagulation by Heat. — When a sample of urine is boiled, a precipitate usually forms. This in most cases consists of earthy phosphates, and is often sufficient to conceal a precipitation of albumin possibly present. If now to the boiled sample about one-tenth its volume of strong nitric acid be added, the precipitated phosphates will disappear, while the albumin will remain coagulated. It is necessary to add as much nitric acid as is here indicated, because a small amount may sometimes dissolve coagulated albumin, forming soluble acid-albumin. This acid-albumin is broken up on the addition of more acid.

Even when boiling does not throw down a precipitate, the addition of nitric acid cannot be omitted, as under certain circumstances the heating may produce a soluble combination between alkalies present and albumin, which is stable. Nitric acid in sufficient quantity will break up this combination and bring about coagulation.

Under most circumstances this heat test, as outlined, is sufficient, and the possibility of making a mistake is very small. It is shown in works on chemical physiology that small amounts of albumin combine readily with weak acids and alkalies, forming soluble and stable combinations known as acid-albicmin and alkali-albumin.

If the urine has a neutral or alkaline reaction to begin with a small amount of alkali-albumin would escape detection by heating alone. On addition of just the proper amount of acetic acid to neutralize the alkali, the application of heat will cause a coagulation, but a slight excess of this acid might convert the alkali-albumin into acid-albumin, equally hard to precipitate. Traces of nitric acid, and in a marked degree hydrochloric acid, behave in the same manner, but the addition of larger amounts of nitric acid is free from this objection because in proper amount this acid is able to decompose both acid- and alkali-albumin.

When taken for examination, urine is frequently cloudy from the presence of precipitated urates or earthy phosphates. Heat is sufficient to dissipate the cloud if due to the urates, but the phosphate cloud is rendered heavier. It is always a good plan to carefully filter the urine, if in the least degree turbid, before undertaking the test.

With old samples of urine which have undergone the urea fermentation and have become alkaline, the test by heat and subsequent addition of acid is not always satisfactory or convenient. In such cases it is best to proceed at once to a method which disposes of the excess of alkali at the start, and in such a manner as to cause no confusion.

Coagulation by Nitric Acid. — As indicated above nitric acid can coagulate albumin, and this test is frequently employed without previous boiling. When applied to fresh urine the test may be made in this manner.

Several cc. of the strong acid are warmed in a test-tube, and over this is carefully poured an equal volume of urine, so as to overlie without mixing. If albumin is present a white ring appears at the surface between the two liquids. When the urine contains an excess of coloring-matter the ring is variously tinted.

If urine is poured over cold acid, a precipitate may appear which is not albumin. This can happen when the urine is highly charged with urea, in which case crystalline nitrate of urea will separate out, or where urates are abundantly present, in which case the ring will consist of very fine crystals of uric acid, or acid urates. Both of these precipitates are dissipated by heat, and if the nitric acid is previously warmed, they cannot appear. It is better to make the test as just suggested than to use cold acid, and then try to warm a ring formed, as this would cause an admixture of the liquids sufficient to obscure a slight amount of albumin.

It is sometimes recommended to pour the urine in a test-tube, and by means of a pipette, or droppingtube, allow the acid to flow under it. This is an excellent method of performing the test, but the acid should be slightly warm as before. If only a trace of albumin is present the ring will not appear immediately, but only after standing. It is well, therefore, in doubtful cases, to set the tube aside for twelve hours and then observe it. If a ring is now found it should be very gently and carefully warmed to determine its behavior toward heat, because on standing in the cold a ring of urates might appear.