Alkaline urine may exist under normal conditions immediately after the ingestion of a large amount of food or fruits. Persistent alkalinity indicates decomposition and usually cystitis. Some drugs-carbonates or organic acids-may render the urine alkaline. Specific Gravity.-Determined by means of the urinometer and is very important, provided a twenty-four hour specimen is tested; otherwise it is of questionable value. Persistent low specific gravity is frequently observed in neurotic people, and does not necessarily indicate a chronic nephritis. High specific gravity is observed in concentrated urines such as occur in fevers, in acute nephritis, and diabetes mellitus. In diabetes insipidus the urine has a low specific gravity. The term diabetes insipidus is a misnomer, because it has no connection with true diabetes. The mixture of the whole amount of urine passed in twenty-four hours must be had in order to make a correct determination of specific gravity. The amount voided in twenty-four hours is of importance. Normally, the average amount is from one to one and a half litres (40-50 oz.). Wide variations may exist in direct proportion to diet, weather, and nervous tension. Chemical Tests The urine should always be filtered before being tested. Albumin.- Heat and nitric acid test: Boil one or two drachms of filtered urine in a test tube. If albumin is present a precipitate appears, insoluble in a few drops of nitric or acetic acid. Earthy phosphates are also precipitated by heat, but these dissolve on the addition of nitric or acetic acid. Picric acid test: Overlay a small quantity of urine by a saturated watery solution of picric acid. If albumin is present, a deposit, insoluble on boiling, forms at the line of junction. For an approximate quantitative test use Esbach's albuminometer. A large quantity of albumin in urine sometimes causes the urine in the test-tube to solidify upon boiling. Albumin is at times present in urine physiologically; this is called paroxysmal (cyclic) albuminuria. A highly albuminous diet (e. g., eggs) may cause albumin to appear in the urine. After severe exertion it is often found; and sometimes it may persist in small amounts in the absence of apparent disease of the kidneys. The diseased kidney usually causes albumin to appear in the urine. All forms of acute and chronic nephritis may cause it to be excreted in considerable quantity. The amount depends upon the severity of the exudative process, the state of the blood, the venous congestion, and the condition of the capillary walls and renal epithelium. In chronic interstitial nephritis the albumin is low in amount and may frequently be absent for long periods. In periods of exacerbation, very large amounts may be excreted. In most febrile diseases, transient or continuous albuminuria may be observed and is referable either to an acute congestion and degeneration of the renal epithelium, or to an acute exudative nephritis. In typhoid fever, pneumonia, meningitis, ulcerative endocarditis, scarlatina, diphtheria, and smallpox, and all febrile diseases, also after convulsions, etc., traces are usually found. In yellow fever, it is often found twenty-four hours after the onset. It may occur in pernicious malaria, and is nearly constant in cases of irritant poisoning. Peptone. In the form of albumose, peptone is found in the urine in many pathological conditions. It is most marked and constant when there is an accumulation with more or less absorption of pus in the body, as in empyema, cellulitis, suppurative meningitis, resolving pneumonia, and suppurating cavities in phthisis; in ulcerative intestinal conditions, such as typhoid fever, tuberculosis, dysentery, and carcinoma. It also occurs in scurvy, pernicious anæmia, leucæmia, diphtheria, the exanthemata, acute yellow atrophy of the liver, pregnancy, and various nervous diseases (myelopathic albumosuria). For a differential diagnosis, the presence of albumose in urine may be of great value to distinguish: 1. Between suppurative and non-suppurative processes, especially tuberculous lesions. 2. Typhoid and other ulcerative intestinal lesions from catarrhal conditions. 3. Exanthemata, diphtheria, etc., from simple fevers. The general practitioner requires the aid of a laboratory expert to make these more delicate tests. Test: a. Separate completely ordinary albumin by boiling faintly acid urine. Filter. · b. Take 50 c.c. of filtered urine, add 5 c.c. of concentrated HCl to acidify. Then add 2 or 3 c.c. of 10 per cent phosphotungstic acid until precipitate ceases to form. c. Heat very carefully in a beaker over a wire-gauze flame until the precipitate becomes an ashy gray resinous mass. The fluid is then decanted and the precipitate washed twice with distilled water to free it from acid. d. Add about 2 c.c. of distilled water and a few drops of 30 per cent solution of sodium hydrate to render it alkaline. Dissolve by gentle heat. If the solution is not colorless, add more alkali, drop by drop, while boiling. This fluid now contains a concentrated solution of albumose. The biuret test is now employed by adding one drop of a very dilute solution of cupric sulphate. The presence of albumose gives a brilliant amethyst red color. Sugar is of significance in the diagnosis of diabetes mellitus. There is a transitory physiological glycosuria after the ingestion of a large amount of sugar, and traces are found when digestion is slightly disturbed. Disease of the pancreas and liver, some drugs, such as chloral hydrate, morphine, alcohol, and chloroform, may cause a slight transitory glycosuria. It is found sometimes during pregnancy, also in some nervous diseases, and in severe and fatal types of infectious diseases; also frequently after hysterical attacks, emotional excitement, and prolonged anesthesia. Fermentation Test: A small piece of ordinary compressed yeast is shaken with some of the suspected urine and a test tube filled with the mixture, to which some mercury is added. The tube is then inverted into a vessel containing mercury and allowed to stand in a warm place (70°-80° F.). If sugar be present, fermentation will occur in the course of twelve hours, and the carbon dioxide formed will rise to the top of the tube, gradually expelling more and more of the urine or the mercury as the amount of the gas increases. As the yeast itself, however, may give rise to the formation of a little gas in the absence of sugar, as lactose, maltose, and levulose also undergo fermentation, and as the internal administration of mercuric chloride, iodoform, salicylic acid, quinine, and other antiseptic drugs may stop the fermentation, the test is of value only as a control-test. Precautions: 1. Urine must be faintly acid. 2. Urine should be diluted so that its specific gravity is approximately 1008. Allowance must be made in result by multiplying by corresponding factors. Take 3. Urine should not contain above 1 per cent glucose. Fehling's Test is probably most used. There are two solutions. equal parts of each solution in a test tube, and dilute once with water. add a few drops of urine, and boil again. Sugar gives a brick-red precipitate. Inasmuch as there are other organic compounds which precipitate the cupric sulphate in Fehling's solution, a control fermentation test should be made; or, for a qualitative test, boiling with potassium hydrate solution seems to be preferable. Urine changes from canary yellow to dark brown, according to amount of sugar present if boiled with this solution. Fill Quantitative Test: The quantitative test is important to ascertain whether the diet and treatment are diminishing the amount of sugar, even though the severity of the disease is not in proportion to the amount of sugar. Procedure: Remove albumin by precipitating, after acidifying, boiling, and filtering the precipitate. Dilute the urine from one half to one fifth. the graduated burette with the diluted. urine. Dilute 5 c.c. of Fehling's solution with 40 c.c. of water. Let it boil over a wire gauze frame. While boiling let diluted urine fall in, drop by drop. Remove the flask from the flame from time to time to allow the precipitate to settle, and to observe the color of the solution. When every particle of blue color has disappeared, read the amount of dilute urine used from burette. The amount of sugar can be estimated from this formula: y: .05: 100 x grms. of glucose. FIG. 1.-EINHORN SACCHAROMETER. y= number of c.c. of diluted urine used. x=grms. of glucose per 100 c.c. of diluted urine employed. Example: If 10 c.c. of urine diluted five times have been used, we have used 2 c.c. of urine. Hence, 2 : .05 :: 100: answer=24. Why? Fehling's solution is of such composition that 10 c.c. requires for complete reduction .05 grm. of glucose. Acetone is found in the urine in severe forms of diabetes mellitus, after ether anæsthesia, and in those diseased conditions in which there is a high degree of albumin destruction, as in high fever, severe anæmias, many carcinomas, acute active phthisis, and in disturbances of digestion. Test: Pour a few drops of a strong solution of sodium nitroprusside into a small amount of urine in a test tube, and make it markedly alkaline. At first a purplish red color appears, gradually turning to yellow. Add two to three drops of acetic acid. The presence of acetone gives a color ranging from carmine to a purplish red. Diacetic Acid and B-Oxybutyric Acid are found in the urine in severe cases of diabetes mellitus. Test: Add strong ferric chloride solution to unboiled urine until all phosphates are precipitated, then add carefully a diluted ferric chloride solution. A Bordeaux red coloration of the urine indicates diacetic acid. This coloration will disappear on heating. The presence of B-oxybutyric acid is detected by the polariscope after eliminating the sugar by fermentation. The ray of light is turned to the left. Bile. Bile in the urine indicates some obstruction to its normal flow. It may be detected in the urine before other symptoms of jaundice develop. Test: If about half an inch of fuming nitric acid be poured into a test tube and a few drops of urine be allowed to float on the top, the presence of bile will give at line of contact a play of colors, red and green predominating. When the fuming nitric acid comes in contact with the urine and a brown or purplish ring forms without a play of color, it indicates the presence of indican. Indican. The presence of an abnormal amount of indican in the urine indicates a putrefaction of albumin somewhere in the body tissues or in the body-cavities, usually of bacterial origin. Indican is almost invariably formed in the intestinal tract (ileum) as the result of proteid putrefaction due to bacterial action, probably the colon bacillus. Test To 5 c.c. of concentrated hydrochloric acid and 5 c.c. of urine add four drops of a half per cent solution of potassium permanganate in water and 2 c.c. of chloroform. If the solution is blue after shaking, indican is present. The intensity of the color indicates the relative amount of indican in the wine. Mucus. The presence of mucus in the urine in abnormal amount indicates an inflammation along the urinary tract, generally a cystitis. Test: Noticed as cloudiness throughout the urine, which has been allowed to settle slightly. Under microscope it is seen as numerous shreds, clumps, or masses, hyaline in character. If urine containing a fair amount of mucus be acidified and boiled, we get a cloudiness similar to that given by albumin. Hæmoglobin. The presence of small amounts of blood in the urine, or derivation from the red blood cells can be demonstrated by testing for hæmoglobin, or its derivatives, with the polariscope. Color test: To a small amount of urine in a test tube, add one fourth its volume of caustic potash and boil. The earthy phosphates will be precipitated. The presence of blood gives the flocculent precipitate a reddish brown color. If the urine is much pigmented, as by bile in jaundice, the color will prevent the reaction. Also look for red blood cells with the microscope. Urea. The normal amount of urea excreted in twenty-four hours is from 20 to 40 grms. (450-600 grains). The diagnosis of a chronic interstitial nephritis without exudation is made by the specific gravity and by estimating the amount of urea secreted in twenty-four hours. A specimen of urine from each of the amounts of urine passed in twenty-four hours should always be employed for examination. Test: Solution sodium hypobromite. R Sod. hydrate (30-per-cent sol.), Water,. 70 parts; 5 parts; 150 parts. As the solution keeps only a few days, it should be made fresh each time. The sodium hydrate solution and the bromine should be kept separate. Fill the apparatus so that when erect no air can enter the tube. The urine should be diluted once. This is not necessary unless the urine is very concentrated. Take 1 c.c. of urine in the pipette, immerse the tip under the bend in the apparatus with great care so as not to allow air to enter, and discharge all of the 1 c.c. into apparatus by slowly pressing the bulb of pipette. None of the air behind the column of urine should be pressed into the apparatus. Allow it to remain for one half hour. Then read amount of solution displaced. The number of milligrams of urea marked on tube are displaced by 1 c.c. of diluted urine. It is a simple calculation to find the total quantity of urea for twenty-four hours in a twenty-four-hours' undiluted urine. Grammes 003 Ureometer E&A. FIG. 2.-UREOMETER. Chlorides. An increase or decrease of chlorides in the urine is of importance. They are increased in polyuria and during absorption of inflammatory fluids. They are decreased in starvation or lack of food, in vomiting, where little absorption of food takes place, in diarrhoea, where there is a serous discharge, and in inflammatory exudative processes, particularly where there are purulent exudations. This is the most important cause for the decrease in the amount of chlorides. The test for chlorides is indirectly a test for purulent inflammations, such as pyæmia, and in pneumonia. The latter disease in some of its phases at times simulates typhoid or malaria. The very small amount of chlorides excreted in pneumonia may be of differential diagnostic value. Indeed, it is said that the prognosis in pneumonia may be determined by the amount of chlorides in urine, as in fatal cases there is almost a complete absence of these constituents. There is frequently a slight decrease several hours before the crisis in pneumonia, before there is any clinical change. Test Remove albumin by precipitating it by boiling the slightly acidulated urine and filtering. Take an inch of filtered urine in a narrow test tube, cool and acidify with one or two drops of concentrated nitric acid. Add one drop of a 5 per cent solution of silver nitrate. A white precipitate is formed of silver chloride. Quantitative Test for Chlorides: Take 5 c.c. urine, diluted so as to subdue the color. Titrate with decinormal silver nitrate solution, using yellow potassium chromate as indicator. End reaction is reached when the orange |