PHYSICAL PROPERTIES OF THE URINE.

Quantity. For a healthy adult the average quantity of urine in twenty-four hours is 1500 c.c., or about 50 fluidounces. The normal variation is between 1200 and 1600 c.c., according to the size, habits, and sex of the individual-for example, a female of average size usually passes less urine in twenty-hours than an averaged-size male. Furthermore, a small adult, male or female, may not eliminate more than 1200 c.c., and yet be in a state of perfect health. The habits of the person have, perhaps, the greatest influence on the twenty-four-hour quantity in health; the habitual ingestion of considerable quantities of liquids, liberal eating, and the like, may cause the quantity to reach 1600 c.c., or even more. On the other hand, exercise, free perspiration, the ingestion of very little liquid, may result in the elimination of a small quantity of urine, even below 1200 c.c.

The quantity of urine in health varies considerably with the time of day, the largest amount being passed in the afternoon, the least at night, and the mean quantity in the forenoon.

The total quantity of urine for twenty-four hours should be accurately measured in every case in which the urine is to be examined, and it is frequently necessary, particularly in disease of the kidneys, to measure the urine every day for a period of one, two, or three weeks, in order to ascertain the average daily quantity. Upon the total quantity depend all quantitative determinations, and, therefore, intelligent inferences as to the capability of the kidneys for work.

Diminished Quantity.—A diminished quantity of urine in twenty-four hours-that is, less than 1500 c.c.-has the following causes: (1) Small quantity of liquid taken; (2) free perspiration; (3) fever; (4) diarrhea; (5) vomiting, and the following renal disturbances and diseases: (6) most cases of active hyperemia; (7) passive hyperemia; (8) first and second stages of acute diffuse nephritis; (9) subacute glomerular nephritis; (10) toward death in all diseases.

Increased Quantity. The causes of an increased quantity of urine in twenty-four hours are as follows: (1) Large quantity of liquid taken; (2) diuretic treatment; (3) nervous excitement and some diseases of the nervous system (frequently in hysteria, and temporarily in cerebral

hemorrhage); (4) diabetes mellitus; (5) diabetes insipidus; (6) convalescence from acute diseases in general, and the following disturbances and diseases of the kidneys: (7) convalescence from a severe active hyperemia; (8) convalescence from an acute diffuse nephritis; (9) chronic interstitial nephritis; (10) chronic diffuse nephritis; (11) amyloid infiltration.

Oliguria is the term applied to those cases in which the quantity of urine is very small, typically seen during the acute stage of an acute disease, also in those chronic diseases that are attended with extensive dropsy.

Anuria is applied to cases in which there is no urine, or when only an exceedingly small quantity is passed-in other words, complete, or almost complete, suppression of urine. This condition is most commonly seen shortly before death, particularly in extensive disease of the kidneys. Total, or nearly total, suppression may last several days— from five to ten.

Polyuria is a term signifying the excretion of a large quantity of urine without any reference to the quantity of total solids in twenty-four hours. Hydruria is a term signifying the excretion of a large amount of urine—in other words, a polyuria-with either a normal quantity or a diminution in the total solids for twenty-four hours: for example, in marked cases of chronic interstitial nephritis, the solids are notably diminished.

Obstructive suppression occurs when there is a partial or complete obstruction to the outflow of urine through the ureters, and is sometimes found to be due to the presence of impacted calculi in both ureters; also to the pressure of a new growth, and occasionally by valves or twists of the ureters. In a case reported by Farlow1 obstruction was caused by a new growth of the uterine appendages, and almost complete obstruction lasted for twelve days.

Retention of urine is the result of an obstruction to the outflow of urine through the urethra, as by a tight urethral stricture, the presence of a calculus in the urethra, or by some mechanical obstruction in the region of the neck of the bladder.

Color. I. The color of the urine under normal conditions is straw or amber yellow. This, however,

J. W. Farlow, "Boston Medical and Surgical Journal," cxx, p. 333.

varies considerably even within the range of perfect health. The color may be said to vary with the dilution or concentration of the urine. Thus, a very dilute urine has a pale color and may be almost colorless, containing a relatively small amount of coloring-matter, and in health is usually the result of copious drinking. On the other hand, a concentrated urine usually has a high color, contains a relative excess of the normal coloring-matter, and is seen when too little water is taken, also after free perspiration and vigorous exercise. It is evident, therefore, that in health the color may range from a very pale or watery color through the yellows to a high or deep red. For practical purposes the color may be termed pale, normal, and high, according to circumstances.

Vogel has constructed a scale of colors of the urine from nature. (See Frontispiece.) These colors are expressed as (1) pale yellow; (2) light yellow; (3) yellow; (4) reddish-yellow; (5) yellowish-red; (6) red; (7) brownishred; (8) reddish-brown; (9) brownish-black. Vogel classifies these colors into groups of three; the first three being yellow, the second three being red, and the last three brown or black. In applying the chart the urine should first be filtered if not already perfectly transparent. It should then be poured into a glass vessel at least three or four inches in diameter, and examined by transmitted light. This color chart is of considerable value as a means for comparison.

2. (a) Under pathologic conditions there is a greater variation than in health, the color being due either to an increase or diminution of the normal pigments, or to the addition of one or more pathologic coloring-matters. Very pale urines are usually attended with a large quantity of urine, as in chronic interstitial nephritis, chronic diffuse nephritis, amyloid infiltration, well-advanced convalescence from acute nephritis, diabetes mellitus, and diabetes insipidus. On the contrary, the urine may have a pale color with a diminished quantity of urine, as in the inactive stage of subacute glomerular nephritis, and in certain chronic affections elsewhere in the body, particularly those accompanied by marked diminution in the normal solids in the urine.

The urine may have a normal color in certain pathologic conditions, particularly in active hyperemia of the kidneys,

frequently in the early stage of chronic interstitial nephritis, and rarely in subacute glomerular nephritis. Occasionally, in diabetes mellitus when the quantity of urine is increased to three or four liters, the color is normal, the result of an absolute increase of the coloring-matters.

Urines having a high color are almost invariably seen in the early stage of acute disease, also usually in active and passive hyperemia of the kidneys, active stage of subacute glomerular nephritis, and in certain diseases elsewhere in the body, notably liver diseases, acute articular rheumatism, and frequently in cases of chronic rheumatism and chronic gout.

From the foregoing it is seen that, either in health or disease, the urine may be pale, normal, or highly colored; consequently, as far as the color alone is concerned, only negative inferences can be deduced concerning the existing pathologic condition.

(b) A dark or smoky urine should always be recognized, for it invariably indicates the presence of an abnormal pigment. Great care should be taken not to confound a dark color with a high color. This abnormal pigment is most commonly found to be decomposed blood pigment (methemoglobin or hematin), although it is frequently seen after carbolic acid has been taken, and occasionally after its use as an external application. It is also occasionally seen after the use of phenol compounds, especially certain drugs, such as salol (when taken in large doses), guaiacol, etc. A urine after the ingestion of phenol is usually normal in color when passed, but on standing exposed to the air soon becomes dark, and may, if allowed to stand a still longer time, become almost black-the result of the decomposition product of the phenol (hydrochinone). A urine containing bile pigment in the form of bilirubin often has a dark color; when such a urine is shaken, the foam will be found to have a decided yellow or greenish-yellow color, and as the urine stands exposed to the air, it soon takes on a greenish, and if much bile is present a marked green, color. The presence in the urine of an abnormal pigment called melanin may cause a dark urine; the freshly passed urine usually has a normal color, but on standing exposed to the air it gradually grows darker from above downward, due to the slow oxidation of the chromogen,-melanogen,-which results in the pigment

melanin. Alcapton, which has a strong affinity for oxygen, produces a dark-colored urine. The urine is usually normal, or high in color, when passed, but on standing exposed to the air rapidly absorbs oxygen, and a dark color results.

(c) A black urine is generally produced by unusually large amounts of those substances which cause a dark or smoky urine, particularly methemoglobin, melanin, and alcapton.

(d) A bloody urine indicates the presence of normal blood and its pigment, oxyhemoglobin. A urine which has a slightly bloody tint should always be distinguished from one having a high color.

It is due to

(e) A blue urine is of very rare occurrence. the presence of free indigo, a result of the decomposition of the indoxyl, which, in all such instances, is present in enormous quantity. Blue urine has been seen in cholera and rarely in typhus fever. When methylene-blue is taken into the stomach, it is absorbed and eliminated in the urine, to which it gives a marked blue or green color.

(f) Urines having a greenish tint are occasionally seen, particularly after the use of an abundant quantity of milk, also in the inactive stage of a subacute glomerular nephritis, chronic diffuse nephritis, amyloid infiltration, and in some diabetic urines with a high percentage of sugar. As previously mentioned, a urine containing bile may, after the bilirubin has become oxidized, have a marked green color.

(g) The urine frequently has an abnormal color after the ingestion of certain vegetable substances, such as santonin, which imparts a yellow color, and rhubarb and senna, which cause a brown or reddish color.

The following table of Halliburton 1 shows the nature and origin of the chief variations in tint: