URS-1P
For the semi-quantitative and qualitative detection of Glucose, Bilirubin, Ketone, Specific Gravity, Blood, pH, Protein, Urobilinogen, Nitrite,
Leukocytes and Ascorbic Acid in urine
SUMMARY
Urine Reagent Strips (URS) for Urinalysis are firm plastic
strips to which several different reagent areas are affixed.
Depending on the product being used, Our Urine Reagent Strips
provide tests for Glucose, Bilirubin, Ketone (Acetoacetic acid),
Specific Gravity, Blood, pH, Protein, Urobilinogen, Nitrite,
Leukocytes, and Ascorbic Acid in Urine. Test results may provide
information regarding the status of carbohydrate metabolism,
kidney and liver function, acid-base balance, and bacteriuria.1,2
Please refer to the outside box and bottle label for the specific test
parameters of the product you are using.
Urine Reagent Strips are packaged along with a drying agent
in a plastic bottle with a twist-off cap. Each strip is stable and ready
to use upon removal from the bottle. The entire reagent strip is
disposable. Results are obtained by direct comparison of the test
strip with the color blocks printed on the bottle label. No
calculations or laboratory instruments are required.
TEST PRINCIPLE
Glucose: This test is based on a double sequential enzyme
reaction. One enzyme, glucose oxidase, catalyzes the formation of
gluconic acid and hydrogen peroxide from the oxidation of glucose.
A second enzyme, peroxidase, catalyzes the reaction of hydrogen
peroxide with potassium iodide chromogen to oxidize the
chromogen to colors ranging from blue-green to greenish-brown
through brown and dark brown.
Bilirubin: This test is based on the coupling of bilirubin with a
diazotized dichloroaniline in a strongly acid medium. The colors
range from light tan to reddish-brown.
Ketone: This test is based on the reaction of acetoacetic acid with
sodium nitroprusside in a strongly basic medium. The colors range
from beige or buff-pink color for a “Negative” reading to pink and
pink-purple for a “Positive” reading.
Specific Gravity: This test is based on the apparent pKa change of
certain pretreated polyelectrolytes in relation to the ionic
concentration. In the presence of an indicator, the colors range
from dark blue or blue-green in urine of low ionic concentration to
green and yellow-green in urine of higher ionic concentration.
Blood: This test is based on the pseudoperoxidase action of
hemoglobin and erythrocytes which catalyzes the reaction of 3,3’,
5, 5’-tetramethyl-benzidine and buffered organic peroxide. The
resulting colors range from orange to yellow-green and dark green.
Very high blood concentration may cause the color development to
continue to dark blue.
pH: This test is based on the well known double pH indicator
method, where bromothymol blue and methyl red give
distinguishable colors over the pH range of 5-9. The colors range
from red-orange to yellow and yellow-green to blue-green.
Protein: This test is based on the protein error-of-indicator
principle. At a constant pH, the development of any green color is
due to the presence of protein. Colors range from yellow for a
“Negative” reaction to yellow-green and green to blue-green for a
“Positive” reaction.
Urobilinogen: This test is based on a modified Ehrlich reaction in
which p-diethylaminobenzaldehyde reacts with urobilinogen in a
strongly acid medium. Colors range from light pink to bright
magenta.
Nitrite: This test depends on the conversion of nitrate to nitrite by
the action of Gram-negative bacteria in the urine. The nitrite reacts
with p-arsanilic acid to from a diazonium compound in an acid
medium. The diazonium compound in turn couples with 1,2,3,4-
tetrahydrobenzo(h) quinolin to produce a pink color.
Leukocytes: This test is based on the action of esterase present
in leukocytes, which catalyzes the hydrolysis of an indoxyl ester
derivative. The indoxyl ester liberated reacts with a diazonium salt
to produce a beige-pink to purple color.
Ascorbic Acid: This test is based on the action of a complex
chelating agent with a polyvalent metal ion in its higher state and an
indicator dye that can react with the metal ion in its lower state to
produce a color change from blue-green to yellow.
REAGENTS (Based on dried weight at time of impregnation)
Glucose: 16.3%w/w glucose oxidase (Aspergillus niger, 1.3IU);
0.6%w/w peroxidase (horseradish, 3300 IU); 7.0% w/w potassium
iodide; 76.1% w/w buffer and non-reactive ingredients.
Bilirubin: 0.4% w/w 2,4-dichloroaniline diazonium salt, balanced
with buffer and non-reactive ingredients.
Ketone: 7.7% w/w sodium nitroprusside balanced with buffer and
non-reactive ingredients.
Specific Gravity: 2.8% w/w bromothymol blue, 69.0%; poly
(methyl vinyl ether/maleic anhydride); 28.2% sodium hydroxide
Blood: 6.6% w/w cumene hydroperoxide; 4.0% w/w 3, 3’, 5, 5’-
tetramethylbenzidine; 89.4% w/w buffer and nonreactive
ingredients.
pH: 0.2% w/w methyl red; 2.8% w/w bromothymol blue; 97% w/w
nonreactive ingredients.
Protein: 0.3% w/w tetrabromophenol blue; 99.7% w/w buffer and
nonreactive ingredients.
Urobilinogen: 2.9% w/w p-diethylaminobenzaldehyde balanced
with buffer and nonreactive ingredients.
Nitrite: 1.4% w/w p-arsanilic acid, balanced with buffer and
nonreactive ingredients.
Leukocytes: 0.4% w/w indoxyl ester derivative; 0.2%w/w
diazonium salt; 99.4% w/w buffer and nonreactive ingredients.
Ascorbic Acid: 5.8% w/w ferric chloride; 4.9% w/w DTPA; 1.2%
dipyridyl; 89.1% w/w buffer and nonreactive ingredients.
WARNINGS AND PRECAUTIONS
Urine Reagent Strips are for in vitro diagnostic use. Do not touch
test areas of Urine Reagent Strips.
STORAGE
Store at room temperature between 15°-30°C (59°-86°F) and out of
direct sunlight. Do not use after expiration date.
RECOMMENDED HANDLING PROCEDURES
All unused strips must remain in the original bottle. Transfer to any
container may cause reagent strips to deteriorate and become
nonreactive. Do not remove desiccant from bottle. Do not open
container until ready to use. Opened bottles should be used within
3 months after first opening.
SPECIMEN COLLECTION AND PREPARATION
Collect urine in a clean container and test as soon as possible. Do
not centrifuge. The use of urine preservatives is not recommended.
If testing cannot be performed within one hour after voiding,
refrigerate the specimen immediately. Allow refrigerated specimen
to return to room temperature before testing.
TEST PROCEDURE
1. Remove from the bottle only enough strips for immediate use
and replace cap tightly.
2. Completely immerse reagent areas of the strip in fresh, wellmixed
urine. Remove the strip immediately to avoid
dissolving out the reagent areas.
3. While removing, touch the side of the strip against the rim of
the urine container to remove excess urine. Blot the
lengthwise edge of the strip on an absorbent paper towel to
further remove excess urine and avoid running over
(contamination from adjacent reagent pads.)
4. Compare each reagent area to its corresponding color blocks
on the color chart and read at the times specified. Proper
read time is critical for optimal results.
5. Obtain results by direct color chart comparison.
Note: All reagent areas except Leukocytes may be read between
1-2 minutes for screening positive urine from negative urine.
Changes in color after 2 minutes are of no diagnostic value.
QUALITY CONTROL
For best results, performance of reagent strips should be confirmed
by testing known negative and positive specimens or controls
whenever a new bottle is first opened. Each laboratory should
establish its own goals for adequate standards of performance, and
should question handling and testing procedures if these standards
are not met.
RESULTS
Results are obtained by direct comparison of the color blocks
printed on the bottle label. The color blocks represent nominal
values; actual values will vary around the nominal values.
LIMITATIONS OF PROCEDURE
Comparison to the color chart is dependent on the interpretation of
the individual. It is therefore, recommended that all laboratory
personnel interpreting the results of these strips be tested for color
blindness.
As with all laboratory tests, definitive diagnostic or therapeutic
decisions should not be based on any single test result or method.
Glucose: Moderate amounts of ketone bodies (40mg/dL or
greater) may decrease color development in urine containing small
amounts of glucose (75-125 mg/dl). However, such concentration
of ketone simultaneously with such glucose concentration is
metabolically improbable in screening. The reactivity of the glucose
test decreases as the SG and/or ascorbic acid of the urine
increases. Reactivity may also vary with temperature.3
Bilirubin: Reactions may occur with urine containing large doses
of chlorpromazine or rafampen that might be mistaken for positive
bilirubin.3 Indican (indoxyl sulfate) and metabolites of Lodine may
cause false positive or atypical color; ascorbic acid (25mg/dL or
greater) may cause false negative results.
Ketone: Color reaction that could be interpreted as “positive” may
be obtained with urine specimens containing MESNA or large
amounts of phenylketones or L-dopa metabolites.3
Specific Gravity: The chemical nature of the specific gravity test
may cause slightly different results from those obtained with the
specific gravity methods when elevated amounts of certain urine
constituents are present. Highly buffered alkaline urine may cause
low readings relative to other methods. Elevated specific gravity
readings may be obtained in the presence of moderate quantities
(100-750 mg/dl) of protein.
Blood: The sensitivity of the blood test is reduced in urine with
high specific gravity and/or high ascorbic acid content. Microbial
peroxidase, associated with urinary tract infection may cause false
positive reactions.
pH: If proper procedure is not followed and excess urine remains
on the strip, a phenomenon known as “running over” may occur, in
which the acid buffer from the protein reagent area run onto the pH
area, causing a false lowering in the pH result.
Protein: False positive results may be obtained with highly alkaline
urine. Contamination of the urine specimen with quarternary
ammonium compounds may also produce false positive results.4
Urobilinogen: The test area will react with interfering substances
known to react with Ehrlich’s reagent, such as porphobilinogen and
p-aminosalicyclic acid.3 This test is not a reliable method for the
detection of porphobilinogen. Drugs containing azo-dyes (e.g. Azo
Gantrisin) may give a masking golden color. The absence of
urobilinogen cannot be determined with this test.
Nitrite: The pink color is not quantitative in relation to the number
of bacteria present. Any degree of pink coloration should be
interpreted as a positive nitrite test suggestive of 105 or more
organisms/ml. There are occasional urinary tract infections from
organisms, which do not contain reductase to convert nitrate to
nitrite.
Leukocytes: Highly colored urine and the presence of the drugs
cephalexin (Keflex) and gentamicin have been found to interfere
with this test. High urinary protein of 500 mg/dl or above
diminishes the intensity of the reaction color. Elevated glucose
concentration or high specific gravity may cause decreased results.
EXPECTED VALUES
Glucose: Small amounts of glucose are normally excreted by the
kidney.5 Concentrations as little as 0.1 g/dl glucose, read either at
10 or 30 seconds, may be significantly abnormal if found
consistently. At 10 seconds, results should be interpreted
qualitatively; for semi-quantitative results, read at 30 seconds only.
Bilirubin: Normally, no bilirubin is detectable in urine by even the
most sensitive method. Even trace amounts of bilirubin are
sufficiently abnormal to require further investigation. Atypical colors
(colors produced which are different than the negative or positive
color blocks shown on the Color Chart) may indicate that bilirubin
derived bile pigments are present in the urine sample and are
possibly masking the bilirubin reaction.
Ketone: Normally, no ketones are present in urine. Detectable
levels of ketone may occur in urine during physiological stress
conditions such as fasting, pregnancy, and frequent strenuous
exercise.6-8 In starvation diets, or in other abnormal carbohydrate
metabolism situation, ketones appear in the urine in excessively
large amounts before serum ketones are elevated.9
Specific Gravity: Random urine may vary in specific gravity from
1.003-1.040+. Twenty-four hour urine from normal adults with
normal diets and normal fluid intake will have a specific gravity of
0.016-1.02210 in severe renal damage the specific gravity is fixed at
1.010, the value of the glomerular filtrate.
Blood: Any green spots or green color developing on the reagent
area within 40 seconds is significant and the urine should be
examined further. Blood is frequently, but not invariably found in
the urine of menstruating females.
pH: newborn: 5-7 thereafter: 4.5-8 average: 6.3
Protein: In 24-hour urine, 1-14 mg/dl of protein may be excreted
by the normal kidney.4 A color matching any color block greater
than trace indicates significant proteinuria. For urine with high
specific gravity, the test area may most closely match the trace
color block even though only normal concentrations of protein are
present. Clinical judgment is needed to evaluate the significance of
trace results.
Urobilinogen: In a healthy population, the normal urine
urobilinogen range obtained with this test is 0.2-1.0 Ehrlich Unit/dl.
A result of 2.0 EU/dl may be of clinical significance and the same
patient sample should be evaluated further.
Nitrite: Normally no detectable amount of nitrite is present in
urine.3 The nitrite area will be positive in a proportion of cases of
significant infection, depending on how long the urine specimens
were retained in the bladder prior to collection. Retrieval of positive
cases with the nitrite test range from as low as 40%, in instances
where little bladder incubation occurred, to as high as 80% in
instances where a minimum of 4 hours incubation occurred.
Leukocytes: Normal urine specimens generally yield negative
results with this test. A trace result may be of questionable clinical
significance and it is recommended that the test be repeated using
a fresh sample from the same patient. Repeated trace and positive
results are of clinical significance.
Ascorbic Acid: The daily urinary output of ascorbic acid varies
with the intake: it approximately half of the intake. The average
urinary output ranges from 20-30 mg/day. If detect ascorbic acid in
urine, stop taking ascorbic acid for 24 hours and retest.
False negative and weak reaction of glucose, blood and bilirubin
may be observed if:
Glucose: more than 50 mg/dl ascorbic acid in the sample.
Bilirubin: more than 50 mg/dl ascorbic acid in the sample.
Blood: more than 10 mg/dl ascorbic acid in the sample.
SPECIFIC PERFORMANCE CHARACTERISTICS
The performance characteristics of the Urine Reagent Strips
(URS) have been determined both in the laboratory and in clinical
tests. Parameters of importance to the user are sensitivity,
specificity, accuracy, and precision. Generally, Urine Reagent
Strips (URS) have been developed to be specific for the constituent
to be measured with the exception of interferences listed above.
(See LIMITATIONS OF PROCEDURE)
For visually read strips, accuracy is a function of the manner in
which the color blocks on the bottle label are determined and the
discrimination of the human eye in reading the test. Precision is
difficult to assess in a test of this type because of the variability of
the human eye. It is for this reason that users are encouraged to
develop their own standards of performance.
Glucose: This test is specific for glucose; no substances excreted
in urine other than glucose is known to give a positive result. The
reagent area does not react with lactose, galactose, fructose, or
reducing metabolites of drugs; e.g. salicylates and nalidixic acid.
This test may be used to determine whether the reducing
substances found in urine is glucose. Approximately 100 mg/dl
glucose in urine is detectable.
Bilirubin: The test has a sensitivity of 0.4-0.8 mg/dl bilirubin in
urine. The test is considered specific for bilirubin in urine.
Ketone: The ketone test area provides semi-quantitative results
and reacts with acetoacetic acid in urine. This test does not react
with beta-hydroxybutyric acid or acetone. The reagent area detects
as little as 5-10 mg/dl acetoacetic acid in urine.
Specific Gravity: The specific gravity test permits determination of
urine specific gravity between 1.000 and 1.030. In general, the
specific gravity test correlates within 0.005 with values obtained
with the reflective index method.
Blood: At the time of reagent manufacture, this test when read as
instructed has a sensitivity to free hemoglobin of 0.015 mg/dl or 5-
10 intact red blood cells/μL urine. This test is slightly more
sensitive to free hemoglobin and myoglobin than to intact
erythrocytes.
pH: The pH test area permits quantitative differentiation of pH
values to one unit within the range of 5-9. pH reading is not
affected by variation in the urinary buffer concentration.
Protein: The test area is more sensitive to albumin than to
globulin, hemoglobin, Bence-Jones proteins, and mucoprotein; a
negative result does not rule out the presence of these other
proteins. The test area is sensitive to 15 mg/dl albumin.
Depending on the inherent variability in clinical urine lesser
concentration may be detected under certain conditions.
Urobilinogen: This test will detect urobilinogen in concentrations
as low as 0.2 EU/dl in urine. The absence of urobilinogen in the
specimen being tested cannot be determined with this test.
Nitrite: At the time of reagent manufacture, this test has sensitivity
to sodium nitrite of 0.075 mg/dl. Comparison of the reacted reagent
area on a white background may aid in the detection of low levels
of nitrite ion, which may otherwise be missed. This test is specific
for nitrite and will not react with substances normally excreted in the
urine.
Leukocytes: This test can detect as low as 10-15 WBC/μL. This
test will not react with erythrocytes or bacteria common in urine.
Ascorbic Acid: This test can detect ascorbic acid in
concentrations as low as 10 mg/dl in urine.
BIBLIOGRAPHY
1. Free, A.H and Free, H.M.: Urinalysis, Critical Discipline of Clinical
Science. CRC Crit. Rev. Clin. Lab. Sci. 3(4): 481-531; (1972).
2. Yoder, J.Adams, E.C., and Free. H.M.: Simultaneous Screening for
Urinary Occult Blood, Protein, Glucose and pH. Amer. J. Med Tech.
31:285; (1965).
3. Tietz, N.W.: Clinical Guide to Laboratory Tests; W.B. Saunders
Company, (1976).
4. Burtis, C.A. and Ashwood, E.R.: Tietz Textbook of Clinical Chemistry
2nd Ed. 2205; (1994).
5. Shchersten, B. and Fritz, H.: Subnormal Levels of Glucose in Urine.
JAMA 201:129-132; (1967).
6. McGarry, J.D.: Lilly Lecture, 1978: New Perspectives in the Regulation
of Ketogenesis. Diabetes 28: 517-523 May, (1978).
7. Williamson, D.H.: Physiological ketoses, or Why Ketone Bodies?
Postgrad. Med. J. (June Suppl.): 371-375: (1971).
8. Paterson, P. et al.: Maternal and Fetal Ketone Concentrations in Plasma
and Urine. Lancet: 862-865; April 22, (1967).
9. Fraser, J. et al.: Studies with a Simplified Nitroprusside Test for Ketone
Bodies in Urine, Serum, Plasma and Milk. Clin. Chem. Acta II: 372-
378; (1965).
10. Henry, J.B. et al.: Clinical Diagnosis and Management by Laboratory
Methods, 16th Ed. Philadelphia: Saunders; (1979).
*Trademark:
Lodineis a registered trademark of Wyeth-Ayerst Laboratories.
Azo Gantrisin and Azo Gantanol are registered trademarks of Roche
Laboratories. Keflex is a registered trademark of Dista Products Company.
