PURDY'S QUANTITATIVE METHOD FOR ALBUMIN IN URINE (CENTRIFUGAL)
Table showing the relation between the volumetric and gravimetric percentage of albumin obtained by means of the centrifuge with radius of six and three-quarter inches; rate of speed, 1500 revolutions per minute; time, three minutes.
VOLUMETRIC PERCENTAGE BY CENTRIFUGE. PERCENTAGE BY WEIGHT OF DRY ALBUMIN. GRAINS PER FLUIDOUNCE DRY ALBUMIN. VOLUMETRIC PERCENTAGE BY CENTRIFUGE. PERCENTAGE BY WEIGHT OF DRY ALBUMIN. GRAINS PER FLUIDOUNCE DRY ALBUMIN.
¼ 0.005 0.025 22 0.458 2.2
½ 0.01 0.05 22½ 0.469 2.25
¾ 0.016 0.075 23 0.479 2.3
1 0.021 0.1 23½ 0.49 2.35
1¼ 0.026 0.125 24 0.5 2.4
1½ 0.031 0.15 24½ 0.51 2.45
1¾ 0.036 0.175 25 0.521 2.5
2 0.042 0.2 25½ 0.531 2.55
2¼ 0.047 0.225 26 0.542 2.6
2½ 0.052 0.25 26½ 0.552 2.65
2¾ 0.057 0.275 27 0.563 2.7
3 0.063 0.3 27½ 0.573 2.75
3¼ 0.068 0.325 28 0.583 2.8
3½ 0.073 0.35 28½ 0.594 2.85
3¾ 0.078 0.375 29 0.604 2.9
4 0.083 0.4 29½ 0.615 2.95
4¼ 0.089 0.425 30 0.625 3.0
4½ 0.094 0.45 30½ 0.635 3.05
4¾ 0.099 0.475 31 0.646 3.1
5 0.104 0.5 31½ 0.656 3.15
5½ 0.111 0.55 32 0.667 3.2
6 0.125 0.6 32½ 0.677 3.25
6½ 0.135 0.65 33 0.687 3.3
7 0.146 0.7 33½ 0.698 3.35
7½ 0.156 0.75 34 0.708 3.4
8 0.167 0.8 34½ 0.719 3.45
8½ 0.177 0.85 35 0.729 3.5
9 0.187 0.9 35½ 0.74 3.55
9½ 0.198 0.95 36 0.75 3.6
10 0.208 1.0 36½ 0.76 3.65
10½ 0.219 1.05 37 0.771 3.7
11 0.229 1.1 37½ 0.781 3.75
11½ 0.24 1.15 38 0.792 3.8
12 0.25 1.2 38½ 0.801 3.85
12½ 0.26 1.25 39 0.813 3.9
13 0.271 1.3 39½ 0.823 3.95
13½ 0.281 1.35 40 0.833 4.0
14 0.292 1.4 40½ 0.844 4.05
14½ 0.302 1.45 41 0.854 4.1
15 0.313 1.5 41½ 0.865 4.15
15½ 0.323 1.55 42 0.875 4.2
16 0.333 1.6 42½ 0.885 4.25
16½ 0.344 1.65 43 0.896 4.3
17 0.354 1.7 43½ 0.906 4.35
17½ 0.365 1.75 44 0.917 4.4
18 0.375 1.8 44½ 0.927 4.45
18½ 0.385 1.85 45 0.938 4.5
19 0.396 1.9 45½ 0.948 4.55
19½ 0.406 1.95 46 0.958 4.6
20 0.417 2.0 46½ 0.969 4.65
20½ 0.427 2.05 47 0.979 4.7
21 0.438 2.1 47½ 0.99 4.75
21½ 0.448 2.15 48 1.0 4.8
Test.—Three cubic centimeters of 10 per cent. solution of ferrocyanid of potassium and 2 cubic centimeters of 50 per cent. acetic acid are added to 10 cubic centimeters of the urine in the percentage tube and stood aside for ten minutes, then placed in the centrifuge and revolved at rate of speed and time as stated at head of the table. If albumin is excessive, dilute the urine with water until volume of albumin falls below 10 per cent. Multiply result by the number of dilutions employed before using the table.

(2) Mucin (Nucleo-albumin).—Traces of the substances which are loosely classed under this name are present in normal urine; increased amounts are observed in irritations and inflammations of the mucous membrane of the urinary tract. They are of interest chiefly because they may be mistaken for albumin in most of the tests. If the urine be diluted with water and acidified with acetic acid, the appearance of a white cloud indicates the presence of mucin.

(3) Albumoses.—These are intermediate products in the digestion of proteids. They have been observed in the urine in febrile and malignant diseases and chronic suppurations, but their clinical significance is indefinite. The following is a simple test: Mix equal parts of the urine, which has been strongly acidified with acetic acid, and a saturated solution of sodium chlorid. A white cloud, which appears upon moderate heating and disappears upon boiling, shows the presence of albumose. If the cloud increases upon boiling, albumin is present and should be removed by filtering while hot. The cloud due to albumose will reappear as the filtrate cools.

2. Sugars.—Various sugars may at times be found in the urine. Glucose is by far the most common, and is the only one of clinical importance. Levulose, lactose, and some others are occasionally met with.

(1) Glucose (Dextrose).—It is probable that traces of glucose, too small to respond to the ordinary tests, are present in the urine in health. Its presence in appreciable amount constitutes "glycosuria."

Transitory glycosuria is unimportant, and may occur in many conditions, as after general anesthesia and administration of certain drugs, in pregnancy, and following shock and head injuries.

Persistent glycosuria has been noted in brain injuries involving the floor of the fourth ventricle. As a rule, however, persistent glycosuria is diagnostic of diabetes mellitus, of which disease it is the essential symptom. The amount of glucose eliminated in diabetes is usually considerable, and is sometimes very large, reaching 500 gm., or even more in twenty-four hours, but it does not bear any uniform relation to the severity of the disease. Glucose may, on the other hand, be almost or entirely absent temporarily.

Detection of Glucose.—If albumin be present in more than traces, it must be removed by boiling and filtering.

(1) Haines' Test.—Take about 1 dram of Haines' solution in a test-tube, boil, and add 6 or 8 drops of urine. A heavy yellow or red precipitate, which settles readily to the bottom, shows the presence of sugar. Neither precipitation of phosphates as a light flocculent sediment nor simple decolorization of the reagent should be mistaken for a positive reaction.

This is probably the best of the copper tests, all of which depend upon the fact that in strongly alkaline solutions glucose reduces copper oxid to lower grades of oxidation. They are somewhat inaccurate, because they make no distinction between glucose and less common forms of sugar; because certain normal substances when present in excess, especially uric acid and creatinin, may reduce copper, and because many drugs—e.g., chloral, chloroform, copaiba, acetanilid, benzoic acid, morphin, sulphonal, salicylates—are eliminated as copper-reducing substances. To minimize these fallacies dilute the urine if it be concentrated, do not add more than the specified amount of urine, and do not boil after the urine is added.