ALBUMINURIA
This is the presence of albumin in the urine. Albumin is a protein, consisting of serum albumin and serum globulin that has been eliminated from the blood plasma. It contains carbon, hydrogen, nitrogen, oxygen, and sulfur. Its exact composi- tion has not been determined.
Urinary albumin does not necessarily indicate diseased kidneys; it may reflect reactions to toxic and nontoxic substances originating within the body. Albuminuria is frequently found in young men who have no other signs of disease. This con- dition is usually transitory. However, albuminuria usually is of clinical significance and generally re- quires further examination.
Methods for Measuring Albumin in Urine
The test is accomplished by means of test strips. Since practically all urine is tested for both glucose and albumin, the tests are combined in the multitest strips. If the strips are unavailable, or positive for albumin, the sulfosalicylic acid method of albumin determination may be used.
Sulfosalicylic Acid Method of Albumin Determination
1. If the fresh specimen is clear, the test may be run without centrifuging. If the specimen is cloudy, centrifuge about 15 ml at 2,000 rpm for 5 minutes.
2. Pour 2.5 ml of clear urine into a test tube measuring 16 mm x 150 mm.
3. Add 7.5 ml of 3 percent sulfosalicylic acid to the urine.
4. Mix by inversion and let stand 10 minutes before reading
5. A white turbidity indicates albuminuria. Compare the specimen with the standards and report as indicated, i.e., 1, 5, etc.
CAUTION: The centrifuge is a carefully balanced machine, and efforts should be made to maintain that balance. Specimens should be placed directly opposite each other in the machine. If only one urine specimen is being centrifuged, place a tube containing an equivalent weight of water directly opposite the urine.
MICROSCOPIC EXAMINATION OF URINE SEDIMENT
Usually performed in addition to routine pro- cedures, this examination requires a degree of skill 6-21 that can be acquired only through practice under the immediate supervision of a competent techni- cian. The specimen should be as fresh as possible, since red cells and many formed solids tend to disintegrate upon standing, particularly if the specimen is warm or alkaline.
Procedure
1. Mix the specimen well.
2. Pour 15 ml of urine into a conical cen- trifuge tube and centrifuge at 1,500 rpm for 5 minutes.
3. Invert the centrifuge tube and allow all of the excess urine to drain out. DO NOT SHAKE THE TUBE WHILE INVERTED. Enough urine will remain in the tube to resuspend the sediment. Too much urine remaining will cause diluting of the sediment and difficulty in reading.
4. Resuspend the sediment by tapping the bot- tom of the tube.
5. With a medicine dropper, mount one drop of the suspension on a slide and cover it with a coverslip.
6. Place the slide under the microscope and scan with the low-power objective and sub- dued lighting.
7. Switch to the high-power objective for detailed examination of a minimum of 10 to 15 fields.
Clinically Significant Findings
LEUKOCYTES—Normally, 0 to 3 leukocytes per high-power field will be seen on microscopic examination. More than 3 cells per high-power field probably indicates disease somewhere in the urinary tract. Estimate the number of leukocytes present per high-power field and report it as the “estimated number per high-power field.”
ERYTHROCYTES—These cells are not usually present in normal urines. If erythrocytes are found, estimate their number per high-power field and report it. Erythrocytes maybe differen- tiated from white cells in several ways:
White cells are larger than red cells.
When focusing in with the high-power lens, the red cells show a distinct circle; the white cells tend to appear granular and the nucleus may be visible.